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Car runs rich and surges at an idle?

Andrew_99GTP

Andrew_99GTP

New member
Ever since my turbo, cam, 65# inj install my car has ran extremely rich and surges at an idle. Could the surging and running rich be a related issue? I am hoping that maybe I have a bad maff or a bad O2 sensor. Does anyone have any ideas? I don't think I have a vac leak because my trims are negative.
 


I swapped out the maff with a different one that is known to be good and it didn't change anything. The car seems to surge really bad when the a/c compressor tries to engage. If I turn the HVAC off it doesn't seem to surge much at all.
 
Ok here is the update. I swapped out the IAC motor, the Maff and installed a Maff screen and now the car seems to not surge near as much as it didn't before. It now bounces between 800-1000 rpms compared to 500-2500 rpms like it was doing. Does anyone think that maybe the maff screen could have caused this. The car seems to idle rough still but I am not sure if it just seems that way because of the polly dogbone mounts I am running. I guess I will know if it has leaned out or not tomorrow when I get a chance to hook PT up to it.
 
why are you running rich at idle? there is no reason to. its almost better for you to run lean at idle.
 
After I installed the mods in my sig I my car was running so rich that I couldn't get any KR (this was running a stock tune other than the IFR table being adjusted for the 65# inj). My trims were -10 or more at times. I really had no idea why either. I ever tried pulling fuel via the maff table and the IFR table but I should have been adding fuel not taking it away. I don't want my car running rich but it is.
 


sit down with a tuner and take some time to make it right. otherwise your car will run like **** because the tune is ****.
 
Andrew_99GTP said:
After I installed the mods in my sig I my car was running so rich that I couldn't get any KR (this was running a stock tune other than the IFR table being adjusted for the 65# inj). My trims were -10 or more at times. I really had no idea why either. I ever tried pulling fuel via the maff table and the IFR table but I should have been adding fuel not taking it away. I don't want my car running rich but it is.
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Running rich, and running a -10 fuel trim are two different things. Running rich means that your AFR is too low and you are running more fuel than you should. A -10 fuel trim means that your tables are commanding more fuel than necessary to keep the car running at the desired AFR. You need to adjust your VE table and you MAF table to account for this accordingly. If you are running rich, you need to change the desired AFR.
 
realistically it depends on how well your setup flows. its not really dependent on mods with how much fuel you need. there are a ton of heavily modded guys that run way leaner than my car ever will.

wideband homie.
 


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