Jerking on low rpm when pressing acc pedal (WRX 2004)
#31
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most stuph is getting used during warm up, to me the LTV info suggesst the ECU is adding a bit of fuel in to get back to 14.7 on cruise. A trim is on the edge of being a little high, B trims look OK but C trim is very high at +11.33 and would suggest either there is an air leak somewhere *or* a sensor fault making the ECU think there is an air leak somewhere.
If you can, check the system over leaks (smoke and pressure test - some leaks will only present at boost pressure). If your sure its not leaking air in or out then check the MAF and o2 sensors for faults and work from there would be my advise.
If you can, check the system over leaks (smoke and pressure test - some leaks will only present at boost pressure). If your sure its not leaking air in or out then check the MAF and o2 sensors for faults and work from there would be my advise.
#32
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I'll try to check it. About fuel trims, these posted are quite fresh (after cleaning MAF I reset the ecu). If I remember correctly, before reset, C trim was lower (about 5-6).
Don't you have any idea why the car is OK during warmup, and symptoms occur only when fully warmed up?
Don't you have any idea why the car is OK during warmup, and symptoms occur only when fully warmed up?
#33
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during warmup the ECU will run different AFR targets and also higher idle target etc. so thinks like poor maf readings/wonky O2/dodgy IACV etc. may go unnoticed until everything is up to temp. Or it could be a poor electrical connection that gets worse when it gets warm - it's difficult to diagnose over a few posts on a forum so you'll have to do a lot of leg work yourself or take it to a garage that can test all the bits for you individually.
#34
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Is ecu keeping engine in warmup mode until it reaches 60 Celcius degrees? If yes, I think we could exclude anything connected directly with temperature, because engine behavior changes exactly at the moment when coolant temperature reaches 60 degrees (read by romraider).
Last edited by uxon; 04 December 2017 at 03:07 PM.