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View Full Version : How do these look for PC-16 fuel trims?



MikeWasHere05
03-19-2008, 09:05 AM
I don't have a wideband but had a gut feeling that I was running rich (from the smell and some backfiring). The fuel trims are within spec though.

This is running at the lowest setting on a 3-5 bar adjustable fpr.

The car seems to be running good though, I was taking a buddys R32 on every type of scenario the other night.

+10.9% @ idle
-8.6% @ pt

MikeWasHere05
03-19-2008, 09:07 AM
On the same tangent, is there anything else I should be looking for? I guess I could make some runs logging timing retard/knock/etc. But is there anything specific?

Solaris
03-19-2008, 09:33 AM
I don't know if adding that much at idle is normal. I know it's "within spec", but it seems like a lot. Check your MAF values at idle, block 003. For reference, my trims are usually at worst -3.1%/-11.2%. MAF value at idle is around 3.4 g/s

MikeWasHere05
03-19-2008, 09:44 AM
I don't know if adding that much at idle is normal. I know it's "within spec", but it seems like a lot. Check your MAF values at idle, block 003. For reference, my trims are usually at worst -3.1%/-11.2%. MAF value at idle is around 3.4 g/s

Alright I'll check it out. I read through Ross-Tech's fuel trim page and I swear to god everytime I read that I find something new.

http://www.ross-tech.com/vag-com/cars/fuel-trim.html


In general, an out-of-spec value in the first field (Additive) indicates a vacuum leak since it is mostly present at idle, when vacuum is highest. An out-of-spec value in the second field (Multiplicative) indicates a fault at higher RPM, and may point to a faulty MAF.

On my list of things to do...

Put bumper back on
Check for boost leaks, build boost pressure tester

Poopie
03-19-2008, 09:58 AM
yup, sounds like a boost leak somewhere. My fuel trims were near perfect with my pc16 set up.

audiFUEGO
03-19-2008, 09:59 AM
+10% idle is way too much

MikeWasHere05
03-21-2008, 10:29 PM
bump, I just remembered.

I found out that my PCV hose was cracked right where it meets up to the engine underneath the intake manifold while I was putting in the oil supply line. To prevent the car from sucking up unfiltered air I just disconnected it from the valve near the intake and stuffed a piece of paper towel in there to close it off. Would that cause the rich problem? I would need to take off the IM to get to that wouldn't I...

Maybe I'll just run a catch can setup if I'm going through all that shit...