Ongoing idle problem, tried everything and car is currently at shop.

[adam355]

My car has a slight idle surge when driving and an almost complete dead idle when the engine is cold. You have to pump the gas to keep rpms up when the motor is cold till it's warm and then it will finally idle with a little surge and a little bogging when driving. I have tried almost everything. No boostleaks, isc motor checks out fine, coolant sensor gives me readings on logger, exc. So anyways I have taken the car to a shop and they are saying that it is running too lean because I think he said it would idle smooth when he would spray carbon cleaner onto the intake filter. Which would kinda explain my high egt's. I currently have stock injectors and no afc adjustments so I have no idea what is up and either does the shop. So if you guys can give me any advice to why the car could be running lean I would really appreciate it.

Please mods do not close this I no it has been beaten to death, but I have tried everything all the old threads suggest on idle surge.

 

[HighPSIRacing]

Sounds like your O2 sensor... It's a common issue on Mitsubishi products, and It's a good place to start! Don't forget to change those plugs (NGK) if they have buildup on them as well.

 

[adam355]

You really think an o2 sensor would cause me this much trouble or are you just throwing an idea out there? I always thought a bad o2 sensor would just cause bad gas mileage by making you run a little rich. Cause now if I wanna change the o2 sensor, it will be expensive because the shop is gonna do it since it's there.

edit: Also forgot to mention the car has a pretty low vacuum.

 

[adam355]

Anyone else have any idea why this thing would be lean? I'm pretty sure it's not the o2 since they are pretty much inoperative at idle anyways.

 

[poopfly]

I'm having an issue similar to this. This first started because my thermastat started going out. Well the wonderful workers at Autozone gave me the wrong seal and I ended up busting the thermastat seal, car got very hot on the ride back home to get the new part. Had to stop twice when it got too hot, didnt want to damage anything more then already had been done. Anyways, got the right seal. Now when I start my car, it will be bogged down when its cold. Usually in second gear, once its up to temp its fine. If I stop and turn car off for awhile, then back on, my idle is messed up and will "pulse" between 8k and 1k until I run it awhile. Any idea's?