Hi, thanks in advance for your help. I have a 98 Ford Escort Sport 5 speed manual tranny with approximately 250000 miles. The motor was changed recently and it has 100000 miles on the new(used) engine. I'm having 2 problems that might be related to each other.
1. Idle speed - the idle speed is normal 50% of the time, 900 to 1000rpm, the other 50% it varies from 300rpm to 1500rpm. Most of the time when it goes wacky, it goes up to 1500 and stays there for an hour or less. Sometimes when I let off the gas, the revs seem to bottom out so much that the car does a nose dive for a split second before returning to a normal deceleration.
2. After accelerating above 2000rpm there is a very noticable hesitation, then it continues to accelerate and then hesitates again. It does this every 300 to 500rpms as its accelerating. If I hold the rpms steady, it doesn't hesitate. It seems to consistently hesitate at 2000, 2500, 2700, 3000 and 3300 rpms.
Neither of these problems cause the Check Engine Light to come on and no codes have been stored. Also, it does this whether the engine is warm or cold. It could be a coincidence, but the problem seems to clear up somewhat after unhooking the battery. But comes back within 10 to 15 miles. It seems to be worse when the outside air temperature gets cold.
Here's what I've done so far:
Replaced melted pcv valve housing and hoses
Checked all hoses for vaccum leaks
Replaced plugs
Replaced wires
Ran 3 cans of fuel system cleaner
Replaced the air filter
Cleaned the throttle body
Removed the fuel rail and checked the ends of the injectors for build up
Cleaned the Mass Airflow Sensor
Cleaned the Idle Air Control Valve
Checked for stored codes, none
Everything else seems ok, fuel economy is great, 37mpg and the car runs out on the road nice and smooth. It's just getting up to speed thats an adventure!!! Any help is greatly appreciated.
Greg