Hey, I've got an old car. 84 Volkswagen Jetta (1.8L engine) with 237,000 on it. I got it fairly recently from a friend, and I was wondering what some of the things I should do to it to increase performance and efficiency are.
So far I have taken my injectors off and cleaned them, and lightly cleaned the throttle body. I think I messed up one of the injectors in the process, and it seems to run rougher, and the injector seals are hard as rocks, so I was planning on pulling some newer style but compatible injectors, with new O rings, from a jetta at the junk yard, after ultrasonically cleaning them. I am also planning on pulling the cat off, because a 30 year old cat with no maintenance probably isn't helping anyone. I am also considering changing the manual transmission oil, because the current stuff might be stock.
I also think i messed up the fuel to air ratio. When I got it, the exhaust smelled like fuel, so I adjusted the fuel to air ratio until the exhaust no longer smelled like fuel. I think the reason it smelled like fuel is because, as I recently noticed, it does have an oxy sensor, but it wasn't plugged in, so I think it was making the mixture as rich as the system was able to automatically adjust for. Keep in mind this has a mechanical fuel injection system. (K-Jetronic I'm pretty sure, google it)
Some other thoughts on it. It doesn't idle very smoothly. Sometimes it idles smoother than other times, but in general I think it should be smoother. Also, I've noticed that the difference between half-throttle and full-throttle is miniscule. Not sure what would cause that. I also know the alignment isn't right, because my front left tire is almost bald while the other tires are in good condition.
My friend that I got the car from said he was getting 30+ mpg from it. So far, on my first fill up I got about 18 mpg, (I had some major timing issues that I think had a big impact on that) and 24 mpg on my second fill up. Its going up :), but I hope to be able to touch the 40's with this car :/. Also, when he had this car, he usually drove 80 miles at a time, and when I use it, I rarely go more than a mile, so the engine is still cold when I get there most of the time.
Ok, I know this car has problems, but what are my priorities in fixing it? Anything I haven't mentioned that I need to look at? Anything else?