Subject: 91 Mits. Eclipse GS
Question: i got a 2.0 dual overhead came in it.. nothing facny just stock 4 banger ya know no turbo no nothing and well i had to replace the tranny in it its a 5 speed manual and i replaced it and as soon as i droped it back down it started having all these new problems... the idol is way out of wack it wont barely run when i touch the gas it kills it... acts as of its osmething with the intake mixture or something like that i dunnot if you would know if it was a certain sensor causing my car not to run or me being able to push on the gas or a vacumn of some sort ive talked to mechanics and the dealership about it and they coudlnt figure it out if you could help me in any sort of way id greatly appreciate it
thanks
Aaron Huls
Answer: Aaron,
I have a few ideas that could cause this problem:

1. There is a ground cable that goes from the tranny to the downpipe. If that ground is not connected properly, that could cause strange idle problems.

2. You should inspect your intake system. Your air filter should be clean and be sure the mass air sensor harness is firmly connected. Remove your throttle body and clean it. It may also be beneficial to remove your intake plenum and clean that too. Also, remove and clean out your EGR valve. That can cause idle problems as well. While you're at it, replace your fuel filter since it's much easier to access with the throttle body removed. Usually, fuel filters should be replaced every two years for normal driving.

3. There are a few sensors that you should check. The Mass Air Sensor and the Throttle Position Sensor. Also, you should check your Idle Air Contol motor. All these sensors are easy to check yourself if you have a repair manual and a multimeter. A manual will tell you how to check all these sensors and tell you the readings you should see on your multimeter.

4. You may have a problem with your car's computer. Read this article for further information:
http://www.90gsx.com/eclipse/cap/caps.htm

If the capacitors in your ECU have leaked and corroided the circuit board, you can have idle problems. Have the ECU inspected and replaced if necessary.
Good luck!