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2002 Dodge Dakota, 3.9L V6, 109K Miles
Downstream O2 Sensor questions
I ran a OBD Scan program from my netbook today and observed the following:
Can someone who knows how O2 sensors work explain which downstream sensor is working correctly, see the attached photo.
This photo shows the O2 sensors after the vehicle has been warmed up to normal operating temp. The downstream are the two on the bottom.
Are we sure this truck even has 4 sensors. Everything I'm seeing says it only has one downstream sensor unless it's California. The poster is in PA.
I'm curious to why you say everything says there isn't 4 sensors, did you look at the photo in original post. you can clearly see 4 sensors.
it's a 02 Dakota 3.9L V6, has the two mini-cats, an upstream and downstream on each mini-cat, these two pipes come together and go into the main cat. then to the muffler... the photo I provided clearly shows 4 sensors if you look at the title window above each sensor. now we got that cleared up, yes i ran the vehicle for long time, its is my daily driver, i run it back and forth to work everyday, 16 miles to work one way, so it is getting heated up. but not thrown one code.
I appreciate all of your help and will hook laptop back up soon and log about 20 minutes worth of driving to post up here to look at.
No, what i see is a window that shows 4 graphs that are labeled as 4 different sensors which doesn't mean much of anything. Unless this is a California emissions certified vehicle, it only has one downstream sensor.
I tried to copy and paste data stream from excel file but it jumbled all together. is there a way to attach an excel file to this?
It doesn't apply the line returns when you do that but you can go back in and edit them in. I was trying to do that for you when you deleted the content.
this data is idling with the pvc hose unplugged, creating a vacuum leak.
32:03.1 Malfunction Indicator Lamp (MIL) Status 0
32:03.2 Number of Emission-Related DTCs 0
32:03.3 Misfire Monitoring Support 1
32:03.4 Fuel System Monitoring Support 1
32:03.5 Comprehensive Component Monitoring Support 1
32:03.6 Misfire Monitoring Completed 1
32:03.7 Fuel System Monitoring Completed 1
32:03.8 Comprehensive Component Monitoring Completed 1
32:03.9 Catalyst Monitoring Support 1
32:04.0 Heated Catalyst Monitoring Support 0
32:04.1 Evaporative System Monitoring Support 1
32:04.2 Secondary Air System Monitoring Support 0
32:04.3 A/C System Refrigerant Monitoring Support 0
32:04.4 Oxygen Sensor Monitoring Support 1
32:04.5 Oxygen Sensor Heater Monitoring Support 1
32:04.6 EGR System Monitoring Support 0
32:04.7 Catalyst Monitoring Completed 1
32:04.8 Heated Catalyst Monitoring Completed 1
32:04.9 Evaporative System Monitoring Completed 1
32:05.1 Secondary Air System Monitoring Completed 1
32:05.1 A/C System Refrigerant Monitoring Completed 1
32:05.2 Oxygen Sensor Monitoring Completed 1
32:05.3 Oxygen Sensor Heater Monitoring Completed 1
32:05.4 EGR System Monitoring Completed 1
32:05.5 Calculated Engine Load 5.882352941 %
32:05.6 Engine Coolant Temperature 199.4 F
32:06.1 Intake Manifold Absolute Pressure 4.496169878 psi
32:06.3 Engine RPM 991.5 rpm
32:06.3 Vehicle Speed Sensor 0 mph
32:06.4 Ignition Timing Advance for #1 Cylinder 10.5
32:06.5 Intake Air Temperature 158 F
32:06.6 Throttle Position 11.37254902 %
32:06.7 Oxygen Sensor Present (Bank 1 Sensor 1) 1
32:06.8 Oxygen Sensor Present (Bank 1 Sensor 2) 1
32:06.9 Oxygen Sensor Present (Bank 2 Sensor 1) 1
32:07.0 Oxygen Sensor Present (Bank 2 Sensor 2) 1
32:07.1 Oxygen Sensor Voltage (Bank 1 Sensor 1) 0.28 V
32:07.2 O2 Sensor Short Term Fuel Trim (Bank 1 Sensor 1) 2.34375 %
32:07.3 Oxygen Sensor Voltage (Bank 1 Sensor 2) 0.76 V
32:07.4 O2 Sensor Short Term Fuel Trim (Bank 1 Sensor 2) 0 %
32:07.5 Oxygen Sensor Voltage (Bank 2 Sensor 1) 0.84 V
32:07.6 O2 Sensor Short Term Fuel Trim (Bank 2 Sensor 1) -2.34375 %
32:07.7 Oxygen Sensor Voltage (Bank 2 Sensor 2) 0.82 V
32:07.8 O2 Sensor Short Term Fuel Trim (Bank 2 Sensor 2) 0 %
32:07.9 Malfunction Indicator Lamp (MIL) Status 0
32:08.0 Number of Emission-Related DTCs 0
32:08.1 Misfire Monitoring Support 1
32:08.2 Fuel System Monitoring Support 1
32:08.3 Comprehensive Component Monitoring Support 1
32:08.4 Misfire Monitoring Completed 1
32:08.5 Fuel System Monitoring Completed 1
32:08.6 Comprehensive Component Monitoring Completed 1
32:08.7 Catalyst Monitoring Support 1
32:08.9 Heated Catalyst Monitoring Support 0
32:09.0 Evaporative System Monitoring Support 1
32:09.1 Secondary Air System Monitoring Support 0
32:09.2 A/C System Refrigerant Monitoring Support 0
32:09.3 Oxygen Sensor Monitoring Support 1
32:09.4 Oxygen Sensor Heater Monitoring Support 1
32:09.5 EGR System Monitoring Support 0
32:09.6 Catalyst Monitoring Completed 1
32:09.7 Heated Catalyst Monitoring Completed 1
32:09.8 Evaporative System Monitoring Completed 1
32:09.9 Secondary Air System Monitoring Completed 1
32:10.0 A/C System Refrigerant Monitoring Completed 1
32:10.2 Oxygen Sensor Monitoring Completed 1
32:10.2 Oxygen Sensor Heater Monitoring Completed 1
32:10.3 EGR System Monitoring Completed 1
32:10.4 Calculated Engine Load 5.882352941 %
32:10.5 Engine Coolant Temperature 199.4 F
32:11.0 Intake Manifold Absolute Pressure 4.35113214 psi
32:11.1 Engine RPM 984.75 rpm
32:11.2 Vehicle Speed Sensor 0 mph
32:11.3 Ignition Timing Advance for #1 Cylinder 8
32:11.4 Intake Air Temperature 159.8 F
32:11.6 Throttle Position 11.37254902 %
32:11.6 Oxygen Sensor Present (Bank 1 Sensor 1) 1
32:11.7 Oxygen Sensor Present (Bank 1 Sensor 2) 1
32:11.9 Oxygen Sensor Present (Bank 2 Sensor 1) 1
32:11.9 Oxygen Sensor Present (Bank 2 Sensor 2) 1
32:12.0 Oxygen Sensor Voltage (Bank 1 Sensor 1) 0.6 V
32:12.1 O2 Sensor Short Term Fuel Trim (Bank 1 Sensor 1) -0.78125 %
32:12.2 Oxygen Sensor Voltage (Bank 1 Sensor 2) 0.76 V
32:12.3 O2 Sensor Short Term Fuel Trim (Bank 1 Sensor 2) 0 %
32:12.4 Oxygen Sensor Voltage (Bank 2 Sensor 1) 0.08 V
32:12.6 O2 Sensor Short Term Fuel Trim (Bank 2 Sensor 1) 4.6875 %
32:12.6 Oxygen Sensor Voltage (Bank 2 Sensor 2) 0.12 V
32:12.7 O2 Sensor Short Term Fuel Trim (Bank 2 Sensor 2) 0 %
32:12.8 Malfunction Indicator Lamp (MIL) Status 0
32:12.9 Number of Emission-Related DTCs 0
32:13.0 Misfire Monitoring Support 1
32:13.2 Fuel System Monitoring Support 1
32:13.3 Comprehensive Component Monitoring Support 1
32:13.4 Misfire Monitoring Completed 1
32:13.5 Fuel System Monitoring Completed 1
32:13.6 Comprehensive Component Monitoring Completed 1
32:13.7 Catalyst Monitoring Support 1
32:13.8 Heated Catalyst Monitoring Support 0
32:13.9 Evaporative System Monitoring Support 1
32:14.0 Secondary Air System Monitoring Support 0
32:14.1 A/C System Refrigerant Monitoring Support 0
32:14.2 Oxygen Sensor Monitoring Support 1
32:14.3 Oxygen Sensor Heater Monitoring Support 1
32:14.4 EGR System Monitoring Support 0
32:14.5 Catalyst Monitoring Completed 1
32:14.6 Heated Catalyst Monitoring Completed 1
32:14.7 Evaporative System Monitoring Completed 1
32:14.8 Secondary Air System Monitoring Completed 1
32:14.9 A/C System Refrigerant Monitoring Completed 1
32:15.1 Oxygen Sensor Monitoring Completed 1
32:15.2 Oxygen Sensor Heater Monitoring Completed 1
32:15.3 EGR System Monitoring Completed 1
32:15.3 Calculated Engine Load 5.882352941 %
32:15.4 Engine Coolant Temperature 199.4 F
32:16.0 Intake Manifold Absolute Pressure 4.35113214 psi
32:16.1 Engine RPM 986.75 rpm
32:16.2 Vehicle Speed Sensor 0 mph
32:16.3 Ignition Timing Advance for #1 Cylinder 8.5
32:16.4 Intake Air Temperature 159.8 F
32:16.5 Throttle Position 11.37254902 %
32:16.5 Oxygen Sensor Present (Bank 1 Sensor 1) 1
32:16.7 Oxygen Sensor Present (Bank 1 Sensor 2) 1
32:16.8 Oxygen Sensor Present (Bank 2 Sensor 1) 1
32:16.8 Oxygen Sensor Present (Bank 2 Sensor 2) 1
32:17.0 Oxygen Sensor Voltage (Bank 1 Sensor 1) 0.06 V
32:17.1 O2 Sensor Short Term Fuel Trim (Bank 1 Sensor 1) 4.6875 %
32:17.2 Oxygen Sensor Voltage (Bank 1 Sensor 2) 0.76 V
32:17.3 O2 Sensor Short Term Fuel Trim (Bank 1 Sensor 2) 0 %
32:17.3 Oxygen Sensor Voltage (Bank 2 Sensor 1) 0.8 V
32:17.4 O2 Sensor Short Term Fuel Trim (Bank 2 Sensor 1) -3.125 %
32:17.5 Oxygen Sensor Voltage (Bank 2 Sensor 2) 0.74 V
32:17.6 O2 Sensor Short Term Fuel Trim (Bank 2 Sensor 2) 0 %
32:17.7 Malfunction Indicator Lamp (MIL) Status 0
32:17.8 Number of Emission-Related DTCs 0
32:18.0 Misfire Monitoring Support 1
32:18.0 Fuel System Monitoring Support 1
32:18.2 Comprehensive Component Monitoring Support 1
32:18.3 Misfire Monitoring Completed 1
32:18.4 Fuel System Monitoring Completed 1
32:18.5 Comprehensive Component Monitoring Completed 1
32:18.6 Catalyst Monitoring Support 1
32:18.7 Heated Catalyst Monitoring Support 0
32:18.8 Evaporative System Monitoring Support 1
32:18.9 Secondary Air System Monitoring Support 0
32:19.0 A/C System Refrigerant Monitoring Support 0
32:19.1 Oxygen Sensor Monitoring Support 1
32:19.2 Oxygen Sensor Heater Monitoring Support 1
32:19.4 EGR System Monitoring Support 0
32:19.5 Catalyst Monitoring Completed 1
32:19.6 Heated Catalyst Monitoring Completed 1
32:19.7 Evaporative System Monitoring Completed 1
32:19.8 Secondary Air System Monitoring Completed 1
32:19.9 A/C System Refrigerant Monitoring Completed 1
32:20.0 Oxygen Sensor Monitoring Completed 1
32:20.1 Oxygen Sensor Heater Monitoring Completed 1
32:20.2 EGR System Monitoring Completed 1
32:20.3 Calculated Engine Load 5.882352941 %
32:20.4 Engine Coolant Temperature 199.4 F
32:20.9 Intake Manifold Absolute Pressure 4.35113214 psi
32:21.0 Engine RPM 978.5 rpm
32:21.1 Vehicle Speed Sensor 0 mph
32:21.2 Ignition Timing Advance for #1 Cylinder 7
32:21.3 Intake Air Temperature 159.8 F
32:21.4 Throttle Position 11.37254902 %
32:21.5 Oxygen Sensor Present (Bank 1 Sensor 1) 1
32:21.6 Oxygen Sensor Present (Bank 1 Sensor 2) 1
32:21.8 Oxygen Sensor Present (Bank 2 Sensor 1) 1
32:21.9 Oxygen Sensor Present (Bank 2 Sensor 2) 1
32:22.0 Oxygen Sensor Voltage (Bank 1 Sensor 1) 0.8 V
32:22.1 O2 Sensor Short Term Fuel Trim (Bank 1 Sensor 1) -3.125 %
32:22.2 Oxygen Sensor Voltage (Bank 1 Sensor 2) 0.76 V
32:22.3 O2 Sensor Short Term Fuel Trim (Bank 1 Sensor 2) 0 %
32:22.4 Oxygen Sensor Voltage (Bank 2 Sensor 1) 0.84 V
32:22.5 O2 Sensor Short Term Fuel Trim (Bank 2 Sensor 1) -2.34375 %
32:22.6 Oxygen Sensor Voltage (Bank 2 Sensor 2) 0.78 V
32:22.7 O2 Sensor Short Term Fuel Trim (Bank 2 Sensor 2) 0 %
Yeah, there is. Don't try to post so much junk.
so not only did we argue about how many O2 sensors I really had I pretty much got no useful feedback from anyone on this forum...
and there is a way to change from the Calif emissions to non-calif emissions...
I pretty much got no useful feedback from anyone on this forum...
I don't think that is a fair statement at all...... Taking my posts out the picture cuz I'll grant there isn't alot of useful info there, I've gone back thru this thread and see a lot of useful info from the other mods... These guys donate their time and knowledge for free and to come in here and say that is bs. You started this thread completely wrong....Rather than stating the problem you had in the 1st post, up front, you start asking about a system that is going to have nothing to do with the driveability problem you are having.... You come in later and spring that little nugget of info on us. So yea that turned what could've been straight forward problem and answer thread into this twisted mess..... Once again, I'm not talking about myself but you have no clue who you are insulting............
I'll put you in for a refund if your not happy with the free service.
Ill send a bill for my time with posting pics and data.
The value of that data is a wash. You've got the magic software program so you shouldn't need us anyway............LOL
I am sitting here looking at generic OBD2 data and nothing really stands out as an indication that something is wrong. Looks like two snap shots were taken at idle with the engine warming up.
You stated the problem your having occurs at when the engine is under load. Your not going to get too much from the OBD2 side if there is a misfire going on. Can't really tell from the vacuum leak you created if the O2 sensor responds or not because we are only seeing one frame of data.
Oops thread got locked...just noticed.
18:42.5 Malfunction Indicator Lamp (MIL) Status 0
18:42.6 Number of Emission-Related DTCs 0
18:42.7 Misfire Monitoring Support 1
18:42.8 Fuel System Monitoring Support 1
18:42.9 Comprehensive Component Monitoring Support 1
18:43.0 Misfire Monitoring Completed 1
18:43.1 Fuel System Monitoring Completed 1
18:43.2 Comprehensive Component Monitoring Completed 1
18:43.3 Catalyst Monitoring Support 1
18:43.4 Heated Catalyst Monitoring Support 0
18:43.5 Evaporative System Monitoring Support 1
18:43.6 Secondary Air System Monitoring Support 0
18:43.7 A/C System Refrigerant Monitoring Support 0
18:43.8 Oxygen Sensor Monitoring Support 1
18:43.9 Oxygen Sensor Heater Monitoring Support 1
18:44.0 EGR System Monitoring Support 0
18:44.1 Catalyst Monitoring Completed 1
18:44.2 Heated Catalyst Monitoring Completed 1
18:44.3 Evaporative System Monitoring Completed 1
18:44.4 Secondary Air System Monitoring Completed 1
18:44.5 A/C System Refrigerant Monitoring Completed 1
18:44.6 Oxygen Sensor Monitoring Completed 1
18:44.8 Oxygen Sensor Heater Monitoring Completed 1
18:44.9 EGR System Monitoring Completed 1
18:45.0 Calculated Engine Load 44.70588235 %
18:45.1 Engine Coolant Temperature 197.6 F
18:45.6 Intake Manifold Absolute Pressure 13.63354737 psi
18:45.7 Engine RPM 2562.25 rpm
18:45.8 Vehicle Speed Sensor 32.31130198 mph
18:45.9 Ignition Timing Advance for #1 Cylinder 15.5
18:46.0 Intake Air Temperature 109.4 F
18:46.1 Throttle Position 49.80392157 %
18:46.2 Oxygen Sensor Present (Bank 1 Sensor 1) 1
18:46.3 Oxygen Sensor Present (Bank 1 Sensor 2) 1
18:46.4 Oxygen Sensor Present (Bank 2 Sensor 1) 1
18:46.5 Oxygen Sensor Present (Bank 2 Sensor 2) 1
18:46.6 Oxygen Sensor Voltage (Bank 1 Sensor 1) 0.78 V
18:46.7 O2 Sensor Short Term Fuel Trim (Bank 1 Sensor 1) -2.34375 %
18:46.8 Oxygen Sensor Voltage (Bank 1 Sensor 2) 0.5 V
18:46.9 O2 Sensor Short Term Fuel Trim (Bank 1 Sensor 2) 0 %
18:47.0 Oxygen Sensor Voltage (Bank 2 Sensor 1) 0.72 V
18:47.1 O2 Sensor Short Term Fuel Trim (Bank 2 Sensor 1) -3.125 %
18:47.2 Oxygen Sensor Voltage (Bank 2 Sensor 2) 0.34 V
18:47.3 O2 Sensor Short Term Fuel Trim (Bank 2 Sensor 2) 0 %
19:31.7 Malfunction Indicator Lamp (MIL) Status 0
19:32.0 Misfire Monitoring Support 1
19:32.2 Fuel System Monitoring Support 1
19:32.3 Comprehensive Component Monitoring Support 1
19:32.5 Misfire Monitoring Completed 1
19:32.6 Fuel System Monitoring Completed 1
19:32.8 Comprehensive Component Monitoring Completed 1
19:32.9 Catalyst Monitoring Support 1
19:33.1 Oxygen Sensor Monitoring Support 1
19:33.2 Oxygen Sensor Heater Monitoring Support 1
19:33.3 Oxygen Sensor Monitoring Completed 1
19:33.5 Oxygen Sensor Heater Monitoring Completed 1
19:33.6 Calculated Engine Load 4.313725 %
19:33.7 Engine Coolant Temperature 161.6 F
19:34.3 Intake Manifold Absolute Pressure 5.221359 psi
19:34.4 Engine RPM 689 rpm
19:34.5 Vehicle Speed Sensor 0 mph
19:34.6 Ignition Timing Advance for #1 Cylinder 14
19:34.7 Intake Air Temperature 131 F
19:34.9 Throttle Position 11.37255 %
19:35.0 Oxygen Sensor Present (Bank 1 Sensor 1) 1
19:35.1 Oxygen Sensor Present (Bank 1 Sensor 2) 1
19:35.2 Oxygen Sensor Present (Bank 2 Sensor 1) 1
19:35.3 Oxygen Sensor Present (Bank 2 Sensor 2) 1
19:35.4 Oxygen Sensor Voltage (Bank 1 Sensor 1) 0.76 V
19:35.5 O2 Sensor Short Term Fuel Trim (Bank 1 Sensor 1) -3.125 %
19:35.6 Oxygen Sensor Voltage (Bank 1 Sensor 2) 0.16 V
19:35.7 Oxygen Sensor Voltage (Bank 2 Sensor 1) 0.8 V
19:35.8 O2 Sensor Short Term Fuel Trim (Bank 2 Sensor 1) -3.90625 %
19:35.9 Oxygen Sensor Voltage (Bank 2 Sensor 2) 0.82 V
Well 16 miles should do it but if your gonna run it to get a datastream, I would make sure at least half of it is at freeway speeds.
Before you take off, check and make sure all the moniters have run or passed.....If the O2 moniter is incomplete, the cat moniter won't run....
We appreciate the pictures to see what you got but......damn dude you didn't have to pull out the tranny for us....
I actually have an 02 Dakota but it's got the small V/8 so we can't get a good baseline from that........
You have California emissions.
I don't frequent new car dealers but MA and CA have had same specs for many years and says so on window stickers. Can't say for sure but I suspect many auto makers just comply to highest standard for many destinations.
MA + CA have done this for ages,
There are only 2 emissions standards. They are "Federal Compliant" and "California and Federal compliant". There are no cars specifically built for Massachusetts or any other state besides California.
I'm not sure what the whole goal of this thread is. The downstream sensors are Cat monitors only and serve no other purpose. They have no input or control over computer decisions for mixture or anything else. If you are not getting a Cat efficiency code, then none of this really matters at all in terms of engine performance.
You can have a blocked or restricted cat than can effect performance but the readings on B2S2 don't reflect that.
It's not a different requirement just that it must meet CA standards to be sold here new anyway. I don't think it applies to used vehicles like CA where alterations are or were once required.
Nothing near me but I'll try to find a window sticker on a new car and take a pic.............
Just looked at a '97 of my own. Says underhood meets EPA standards for California and I know that was sold new to upstate, NY??!!
Dunno - that's how things are marked here not a MA sticker but must meet CA standards?
I'll see if I can Google out that confusion............
ok, so I live in PA, the Carfax report says it was originally sold as a corporate vehicle right here in PA. Do you know why it has Calif emissions? and could I redo the exhaust without the mini-cats and have just two sensors? What would I have to do besides the wiring harness, change the computer too or could it be done with dealer programming tool?
What are your suggestions?
No, you can't change it. It is what it is. It was built with a package to be California compliant and that's the way it will always be.
DS is right....There just isn't enough info here to even guess at it...
Under all the right conditions it would look like one cat is bad.....But if you haven't run it long enough to fire off both cats then it could just be a case of one of them being to cold...
You should also check to see if all the moniters have run and passed. If you have any incomplete ones then other ones won't run until they run & pass...
If you have an incomplete O2 moniter then you may have a cat code looming to set as soon as the O2 moniter runs & passes....
Are you getting a P0430 code because Bank 2 catalyst isn't cleaning the exhaust. What rpm was the engine at?
Bank 1 appears that it is doing something and the cat on that side is working. Bank 2 sensor is working because it is fluctuating. You can tell if Bank 1 is responsive by stabbing the gas pedal a few times to richen up the exhaust and see if the O2 responds.
So are you leaning toward the downstream sensor bank 2 sensor 2 (bottom right graph) indicating the mini-catalyc converter is bad? Would this cause stutter or poor performance when running in overdrive and a load on the motor?
Bank 2 catalyst isn't cleaning because the rear sensor pattern is mimicking the front O2 sensor. The Bank 1 side appears to be working.
Were you driving the vehicle at the time the stuttering was occurring when this snap shot was taken?
You want to resolve your drive-ability problem first before condemning the cat. A cat this isn't cleaning won't necessarily cause a drive-ability problem unless it is plugging up the exhaust.
Does your program have the option of viewing misfire data?
it checks to see if the misfire check circuit ran which it does, but i get no codes indicating a misfire.
There might not be enough misfires occurring to cause the light to come on. The misfire monitor is active, but you might not be able to view current misfire pids with your program.
If the engine feels like it is skipping under load. That is usually caused by ignition secondary issues such as spark plug wires breaking down. How are the plugs, wires, cap, and rotor?
Misfires due to an ignition problem will reek havok with the catalyst because the unburnt fuel from the misfiring will cause the catalyst to overheat if there are enough of them.
plugs wires cap and rotor and coil all brand new motor has 109K on it. did compression check all about 180PSI
What are your long and short term fuel trims for both banks at the time of the stutter and loss of power? Can you snap shot a data list and post it up on here when the problem is occurring?
I am getting no codes at all.
2003 Chrysler mini van. 3.3 ltr 133600 mi
while driving, engine light came on battery light came on, temperature gauge went off, shifting became sluggish, idle speed went up. It still ran. I turned it off and restarted it. at first engine light only was onand the temperature gauge was working.within 30 seconds temperature gauge went off and the battery light came back on
Can a PCM be replaced by anyone or is it too technical for the average guy?
Physically replacing it isn't really hard. Programming it is something that most DIY can't do. You would have to find someone local to program it.
Ok, i took to mechanic. He replaced two sensors and then the alternator. 750 dollars later still not fixed. So I got a PCM from computer exchange place. Programmed to my vehicle. Followed instructions and installed it. Ran a little rough at first then smoothed out. Drove fine all day. Went to work next day and it happened again. Exactly like before when problem first happened. Any thoughts?
Arggh. Right away when picked up at the mechanic's and did the same thing why didn't you bring it up right then and there before leaving?
Clearly problem not fixed and has run poorly enough for new things to be the issue. IDK what to suggest except get codes again now as if running poorly there are and if not a problem not communicating with the vehicle,
Lol. When picked up at mechanics, I had spent 750 and he still had no clue. He guessed computer which most would have tried at the beginning but quoted me another 750 to fix that. No thank you. I did computer myself
So I got the codes again. Four this time. 0106, 0118, 1478, and a new one: 1496. I am guessing that the wiring harness has a short, or that five volt reference thing is off. I don't know how to check it or fix it.
Poor communication so do think wires and vacuum issues to bad grounds? IDK from here. It worked for a while so on comes the guessing that something in that area just being bumped has the problem.
From some older threads not witnessed was that battery placement was or could be a spot under it with assorted items that could be harmed by location or possible acids from battery? A place to look.
Dang - lotta cooks in this kitchen and no chef seems to be an issue as well,
If you have a P1478 code popping up, it appears you'll need to replace the PCM. You should definitely make sure the PCM has good powers and grounds and that your 5 volt reference isn't being pulled down before replacing the PCM though. Just to be on the safe side.
I guess no one verified 5 volt ref when the problem was happening??
Yes, you should really focus on the 5 volt reference circuit. You might need a DSO to monitor the 5 volt reference to see if it drops out when the problem occurs. Might be able to catch it with a volt meter if the 5 volt ref is down long enough for you to start unplugging sensors one at a time to see if it comes back up. Your going to need a wiring schematic and connector pin out. The fun part is going to be finding the problem with the circuit because many sensors uses that 5 volt reference.
While your monitoring the 5 volt ref, wiggle wiring harness around to see if you can duplicate the problem. Hopefully your replacement PCM doesn't have the same issue as the old one.
Even though this video is of a Caddy with a shorted 5 volt ref, the procedure is the same. :
So I sent in both computers to have them checked. Turns out neither one was bad. It's not the computer. So much for that idea. Lol. Now I'm guessing it's a short. So where would the short be, and how to find it? That's the question. I am still thinking that the battery light coming on and the temp gauge becoming inoperable is a clue. Wish I personally knew a mechanic worth his salt
So I just drove it to get gas. Ran fine. Temp gauge worked fine too. Shifted normal. Idle speed correct. Turned it off. Got gas. Turned back on and temp gauge quit, idle increased, shift became sluggish again. Lol. It definitely has something weird going on with that gauge. Gauge working van working, gauge not working van has problems.
Did NOT reread whole now old and long thread but when you have an intermittent much of anything and if when checked all is fine you are in trouble.
Problem must show itself while happening if not something in memory of something which may be lost when checked. Now if you have the most info, tools, equipment and know how and everything works fine when checked what would you do?
I did see that a whole cluster was a common issue was a clue and other than parts tossing at some point you need to or find someone to actually chase wiring one end to the other all over.
Just general on electric snags is that grounds that make whole metal of body grounded lose or break straps here or there and can be the problem for intermittent electrical or any connection of a harness for that matter. This isn't fun work and can use a lot of luck sometimes to know you've actually found and fixed something of the sort,
So I have fixed my problem. No it was nothing that any code showed. It was a short in the wiring harness. The codes made the mechanic I took it to change things that were fine. That is what I was afraid of in the first place. Today's mechanics are typically code driven. Find the code then change out a part. I solved the problem through research. I found others with the same problem who told me where they found their short. Anyway, there is part of the harness that is close to exhaust pipe. It's located behind the power steering reservoir. Turns out that it is common for the wires to melt there. Sure enough. Fixed the insulation which fixed the problem. Hopefully this can help others fix their problems.
Today's mechanics are typically code driven. Find the code then change out a part.
No, that's not the way it works. The computer has a self monitoring system and the codes alert the mechanic when the computer sees a malfunction. The codes do not tell anyone to change any parts. They describe a specific situation that the tech has to then troubleshoot to find the cause. A car can have a problem that doesn't set a code either so your vehicle may have had multiple issues so today's mechanic do not change parts unnecessarily. They troubleshoot known issues.
Thanks for posting the source of the problem and the fix. Locked for archives for others to view OR you may request it re-opened by any moderator, T
Ok. I understand what you all are saying. I guess my main complaint was that I listed a list of problems that all occurred suddenly. It didn't seem like anyone even looked at the symptoms listed. Oh well, water under the bridge. I got the readout from O'Reilly auto. Codes are P0118 and P1478 and P0106. Also, the PCM was changed 30,000 miles ago. Just for your info. Thanks.
The P0118 addresses your temp gauge problem and is likely causing some serious fuel mixture problems also. There is an issue with the temp sensor. Look at the wiring and plugs before changing the sensor.
The P1478 is a problem with the battery temp sensor which is why your battery light is on.
The P0106 is an issue with the MAP sensor. Again, look at the wiring and connectors and the vacuum supply.
See how much help those codes were. They are all likely unrelated too although a damaged wiring harness could effect all 3.
If you have a P1478 code popping up, it appears you'll need to replace the PCM. You should definitely make sure the PCM has good powers and grounds and that your 5 volt reference isn't being pulled down before replacing the PCM though. Just to be on the safe side.
The PCM incorporates a Battery Temperature Sensor (BTS) on its circuit board.
The PCM uses the temperature of the battery area to control the charge system voltage. This temperature, along with data from monitored line voltage, is used by the PCM to vary the battery charging rate. The system voltage is higher at cold temperatures and is gradually reduced as temperature around the battery increases.
The ambient temperature sensor is used to control the battery voltage based upon ambient temperature (approximation of battery temperature). The PCM maintains the optimal output of the generator by monitoring battery voltage and controlling it to a range of 13.5 - 14.7 volts based on battery temperature.
The battery temperature sensor is also used for OBD II diagnostics. Certain faults and OBD II monitors are either enabled or disabled depending upon the battery temperature sensor input (example: disable purge and EGR, enable LDP). Most OBD II monitors are disabled below 20 Â°F.
Not ticked off. I know to get it read. Was hopeful somebody might have a clue before a read out. But hey, who am I to get in the way of everyone's sarcastic wit. Once I have the reading done, well let's see, I know, I can just ask the mechanic who did the read out. Hmmm. Wonder why this site is even up and running? Gee what would we do without computers to tell us what's wrong? Lol. It's funny, cause my brother could at least offer a diagnosis based on vehicles he's had before. That would be sharing experience, but oh well, thanks for the tips. .. get a read out. ..
Your thread title refers to troubleshooting. Taking WAGs is not troubleshooting. Cant even offer a suggestion without some data. Once you get codes read, that MIGHT offer a starting point for diagnosis. Anyone who offers you a guess does not value your time or money. You can have similar symptoms caused by a large number of different issues (refer to DSs guess), thats why testing is required to narrow it down. Parts stores are real good at guessing, good techs are not.
CARR if you are still following here -
Thiis is the misconception we as technicians face daily - the misunderstanding that a DTC is the corrective action - the 'code' will tell us what to change. That ]is not the case, NO code says change a part- the people at part stores that do the FREE service say buy this part.
If the vehicle overheats, sets a code* for temp sensor high - flawed part store laymen logic-code says temp sensor SO the sensor needs replaced.
It is just the messenger- example- the technician knows to look for the leaking hose
* p011x, P111x etc
Sorry. It's just that 99.9% of vehicles can't tell you more than a trouble code has been set. Takes reading what it sees and interpreting that info to continue on for the fix.
It monitors so much to do with how the engine runs, emissions, transmission and shifting and another 100 things not at the tip of my tongue. Owner's manuals that NOBODY EVER READS would tell you just what to do if that light is lit.
Codes at some parts outlets can be read for free - chains like Autozone and many others but write #s down not just what it might suggest the exact fix is.
If the vehicle isn't running perfectly it's possible to cause damage to wait. I'm not thrilled with putting too high of techno stuff in a moving machine exposed to the elements that controls the whole show much either as they get older that can be the problem but when it all works right it gives the most accurate adjustments for the temps and loads on a vehicle, the least pollution and best fuel economy too.
This could be as silly as a missing or loose gas cap or who knows till codes are read and the fix determined with that info,
I'd like to invite someone to our shop that believes a scan tool or code reader tells you what exactly is wrong and which part needs replacing. If I popped the datastream up for the BCM or MIC on that thing and told the visitor to tell me what is going on, they would shit their pants.
Just give them a factory flow chart for a code, any code.
Listen friend, cars don't talk to people and say, "Ouch my muffler has a boo boo." Scanners and scan tools are not magical devices that tell you what to replace. Being a modern day technician is a cross between a detective, network technician, and electronics engineer. Cars are no where near as easy to diagnose as back in the old days with points and a carbs.
We don't guess because when you guess 80% of the time you'll be wrong. We can't afford to be wrong when we are responsible for repairing other people's vehicles for a living. Heck, the wrong diagnosis could get someone killed in extreme cases.
If your here to troll the forum, your not going to be here very long. If your here looking for good advice and pointers on which direction to go to solve your problem, this is a great place.
This is one of those guys that thinks that magic little box that you plug into the car tells you exactly how to fix everything. Don't need a mechanic if you got one of the magic boxes.
Probably a bad dash cluster. they have a lot of problems.
scan for codes EVEN if the CEL now is off
First of all. Check engine light is on and stayed on, second, anyone can say scan codes. I was looking for an experienced mechanic who might have an idea what would cause the symptoms. Wow
Checking for codes is the first step in troubleshooting.
GUESSING is NOT the way professionals approach an issue- that would be the crystal ball, psychic type.
I will add the collective experience is likely 25years PLUS per site contributor.
So you are unsure why/how the Dash cluster could cause rough shifting and high idle?
In laymans terms the PCM (computer) is seeing an issue and acting accordingly.
So how do we determine WHAT the PCM is seeing/reacting to ?
THAT would be getting the DTC's -
Need ideas on doing that?
Quote"First of all. Check engine light is on and stayed on, second, anyone can say scan codes. I was looking for an experienced mechanic who might have an idea what would cause the symptoms. Wow "
Gee - you sound ticked off that the vehicle is warning you to CHECK CODES and upset about it. 100s of areas possible and reading them narrows it down so that is the professional response to you inquiry or just give up and send you down the road,
Hell, I take a guess. Faulty BCM, faulty MIC, wiring problem, terminal tension issue, faulty ignition switch, loose fuse, faulty power distribution box, poor grounds, EMI, excessive alternator AC ripple, communication bus problem .... Take your pick and let us know what you figure out.
Dash cluster? How could that cause rough shifting and high idle?
I agree with KEV
About 5 months ago I bought a 1994 S-10 Blazer with a 4.3L Vortec engine code W, 4 wheel drive, auto transmission with roughly 166,000 miles. It wouldn't start and after checking fuel pressure found out the fuel pump wasn't working. I went ahead and bought a new AC/Delco pump, pulsator, strainer, electrical connector w/pigtail, sending unit, dist. cap, rotor, plugs and wires, 2 fuel filters, changed engine oil and filter replaced the exhaust from the cat convertor back (old muffler and exhaust was rusted badly). Dropped the fuel tank and cleaned it out and installed the pump and sending unit. Put the tank back in the vehicle, installed one of the new fuel filters in the fuel line and put all the ignition stuff I bought in it. Put a fuel pressure gauge on it and made sure everything was working. I had fuel to the pressure gauge at the schrader valve so it seemed I was ready to fire it up. I tried that and it wouldn't start. I had hot blue spark but no fuel was getting to the plugs. I read in my manual that any problems found with the CMFI unit the entire assembly should be replaced. Well I was short on cash so I pulled the upper plenum and took the unit out, sprayed carb cleaner in the poppet valves and rusty nasty smelling fuel came out. Used some air (low) and blew everything dry and reinstalled it. Put on a new plenum gasket and bolted everything back together. After everything was bolted down and electrical connectors were back together I got in turned the key and within a few cranks of the engine it fired up. I let it warm up while I cleaned up the shop and took it for a drive. Everything was working fine. Drove it everyday to work for just over 4,000 miles then one day on the way home on the highway going up a hill I noticed I was losing power. Never did die but I had to step lightly on the peddle. Anymore than that and the engine rpm's fell. I made it home and when the weekend came I took it back out to the shop and decided to do some testing. Didn't know about this forum but I had the repair manual.....heck I can fix this myself...yeah right. I read in the manual that if the fuel pressure didn't approach 61lbs. on acceleration that the pressure regulator on the CMFI unit was bad and it should be replaced and this past weekend I replaced it. Well after doing some further reading I found out that its a good idea to replace the fuel line assembly (nut kit). I didn't do that and I really didn't look over the plenum to see if there was any wash. Well it's still doing the same thing it was doing. I put a fuel pressure gauge on the schrader valve and here is what I found out. With the key on/engine off and the fuel pump running I have 60lbs. as soon as the pump shuts off the pressure drops to 58lbs but within a couple seconds climbs back up to 60lbs. I turned the key off and let everything set for 10 minutes and the fuel pressure then was 58lbs. I started the engine and the pressure was between 51lbs. and 58lbs. (needle was fluttering back and forth). I increased the throttle to 2,000 rpm's and the pressure gauge needle flutters between 49 and 60lbs. Around 2500 rpm's and the engine starts to cut out, bog down or whatever. It won't throttle up anymore than that. It starts good and idles good and I can drive it in town but I can't take it out on the highway. I put a vacumn gauge on it and at idle it has 19 lbs/inches? and if I increase the throttle it increases to around 21 or 22 lbs/inches. I didn't pinch the return fuel line to see what would happen to the fuel pressure but I think I performed everything else. I'm really leaning towards replacing the fuel line assembly (nut kit) like I should have done when I replaced the CMFI unit. All the fuel pressure readings stay the same with the engine cold or when it's at operating temp. What do you guys think? Where should I go from here? Sure would appreciate any help you can give me. Sorry for the long winded post but I wanted you to know what all I've done.
Also wondering what would make the fuel pressure gauge needle flutter? Don't believe it's supposed to do that.
What does the fuel pressure look like with the vacuum disconnected at the pressure regulator? Should be stable, then. If the engine is running lean or rough, the vacuum will be unstable and that will affect the regulator. The Vortecs are know for the fuel feed lines leaking and also the poppet valves on the injectors. If the pressure is stable, although high, with the regulator disconnected, I'd at least 'try' cleaning the injectors/poppets. If you have the capability, I'd take a gas reading of the intake after sitting to see if you have a high CO/HC reading. That should tell you if you have a fuel 'leak'. We've 'fixed' many a poppet leak with cleaning. The "injector cleaner" in a can, IMO, is snake oil. I suppose it's okay for in-between cleanings, but have them cleaned professionally if everything else checks out.
Thank you for the reply and advice. I really do appreciate it.
Unfortunately the fuel pressure regulator is attached to the CPI unit under the plenum (upper intake manifold) and has no vacumn line to it so I can't do anything with it. The CPI itself has an electrical connector.
I just replaced the CPI unit so its brand new. The poppet valves also were attached to the CPI so they're new also.
The engine idles perfect and it runs great up to around 2500 rpm's and thats where it starts cutting out or bogging out. It's not hard to start nor does it die even if I hold the throttle pedal to the floor. Just no acceleration.
I went to the parts store and ordered a new fuel line assembly (nut kit..both intake and return lines inside the plenum that fasten onto the hard lines on the outside of the intake manifold) and also ordered the injector electrical connector and another plenum gasket.
I'm going to go ahead and install them and see what happens. Hopefully that will solve my problem.
If not then at least I will know that everything under the plenum (intake manifold) should be good to go.
I will post back here my findings on what happens when I get that done in the next day or two.
Thank you again for your help.
Sam - no harm intended but for goodness sakes try to separate your thoughts! I've never seen such a run on paragraph in web history!
Ok: Two bits out of all of this. The subject line and a vacuum reading.
22hg at a raised idle when 19hg was the baseline suggests your reading was a "venturi" effect vacuum port not 'manifold actual pressure' -- now get an actual vacuum reading and read it at 2,000 rpm held steady.
This smacks of a restricted exhaust or that you are working on it at about 1 to 2 thousand feet below sea level,
Last night at the shop I took off the catalytic convertor and put a piece of straight pipe in its place. Here in my state we don't have vehicle inspections. You could hardly see through the convertor so I thought maybe that was the problem. Nope. Still starts and runs good up to a quarter throttle when it bogs down.
Took the vacumn gauge and hooked it up to the intake manifold and it holds steady in the normal range on the gauge at 19-20 hg. At 2,000 rpm is raises slightly to 21 or 22 hg.
Fuel pressure was the same numbers I posted earlier. Fuel pressure gauge needle is still fluttering too. Hooked the gauge up on my friends dodge mini van and it holds steady doesn't flutter so the gauge isn't at fault.
Don't really know what direction to turn now.
I guess I should have spent the money and let a shop check and fix it. Hindsight...I know.
Any other suggestions? It's the only vehicle I have to drive.
Sam; Don't know why I didn't suggest this earlier. It's not a normal symptom, but have you looked at the MAP readings? What if..the MAP isn't seeing a drop in vacuum when under load? I doubt that a TPS would cause this type of symptom, either, but at this point, I'd check it.
I didn't think of that either. Will do some reading in the repair manual and see what I have to do to check it out or get the readings. Worth a shot. Will let you know what I come up with. Thank you
I ended up taking my S-10 Blazer into a shop and have them fix it.
They found out that when the engine started to bog down that loud noises were coming from inside the fuel tank. They pulled the tank and along with a faulty fuel pump the inside of the tank was loaded with crap. All this combined to make my fuel pressure gauge needle flutter like wild. They told me when they had it hooked up to their machine that when they sprayed carb cleaner through the intake that the engine rpms increased and thats what led them to the gas tank and ultimately the fuel pump.
The pump was under warranty but I guess when the parts store asked about tank contamination the warranty went out the window. After a thorough tank cleaning and installation of a new pump and fuel filter its running like new.
I cleaned out the tank as best I could when I put the old (new) fuel pump in it but evidently I didn't do that good of a job. Only lasted a few months before the crap in there took out the pump.
Thought I would pass along what transpired to all of you. Thank you once again for all your advice.
Sam; Thanks so much for the reply. Let's keep our fingers crossed that the pump was the problem. I did have a similar situation, many years ago. We finally, out of desperation, pulled the fuel tank and found newspaper wrapped around the pickup. Turned out that the guy had run out of gas and used a rolled up newspaper as a funnel. Drove us nuts trying to find the culprit, but that took care of the problem. Good luck.
No problem Loren. There was alot of crud in the tank that evidently I didn't get out when I replaced the pump a few months ago but I didn't have much to work with like an auto shop does. She runs excellent!!!!
Took it for a 200 mile drive today and she never missed a beat. Way cool.
Ok The vacuum reading is probably ok just off by calibration but useful. It would be lower at 2,000 rpm with an exhaust restriction but really shouldn't ever be steady at 22Hg as that's a bit much. In fact with same test it should spike up there when a quick rev is done but not hold there normally. Air speed/the venturi effect can cause higher vacuum readings but I think you have the actual reading and the suspect item would have been the converter which you seem to have ruled out.
It does belong back in as it's part of the system and may be making improper adjustments with it missing - especially any post converter sensors.
I simply don't know what would be causing the fuel pressure fluctuations you mention and that probably is a source of the trouble,