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Avant Nate
02-28-2014, 03:37 PM
After fixing a few things, throttle body and broken n75 wiring, a few days ago I pulled a code for p1137, long term fuel trim too rich. My AFR's at cruise are good and at boost, but at idle, I would sometimes see it drop down, and now after taking it out and actually watching, my AFR's drop down into the 10's after I let off the throttle, and then slowly build back up to mid 14's.

So looking at my fuel trims today, they are all over the place. At idle, my stft sits -29.7% but at cruise it will vary a bunch but generally leans harder to the negative side. I tried clamping the lines to the purge valve to see if that had any effect, but still -29.7%, and I tried lowering my fuel pressure last night, but no change at idle, and it ran a touch leaner, but I wasn't comfortable with it.

Any suggestions on where to start?

Seerlah
02-28-2014, 03:52 PM
What tune?

Avant Nate
02-28-2014, 03:54 PM
Unitronic 415 with 034 billet maf

Seerlah
02-28-2014, 03:56 PM
How long has this been happening for? What connections did you unhook when you fixed those issues in post 1?

Avant Nate
02-28-2014, 04:10 PM
It was relatively quick after resetting the ecu, but O2 correction of -29.7? How do you test injectors?

Seerlah
02-28-2014, 04:22 PM
I'm thinking that o2 correction is because of a faulty MAF reading. Just guessing right now. Not quite sure how to test injectors, but they seem to be operating properly if you are getting -29% fuel trim. You need to find out what is telling the ECU to do that.

Avant Nate
02-28-2014, 04:35 PM
I'm thinking that o2 correction is because of a faulty MAF reading. Just guessing right now. Not quite sure how to test injectors, but they seem to be operating properly if you are getting -29% fuel trim. You need to find out what is telling the ECU to do that.

I say that because maybe I have a leaky injector thats dumping to much fuel. I just cleaned the MAF,(i know thats worthless), so I'll see if that makes any difference.

rockersteady
03-01-2014, 03:13 AM
Check that the maf entrance is unobstructed, it can cause higher airflow across the sensor.
Normally the only reasons for running rich at idle/ part would be:

1. Maf overeading (such as obstruction increasing the velocity of air across sensor OR incorrect housing, OR sensor not centered) What is the maf reading at idle once fully warm with everything off?
2. Too much fuel (wrong pressure/ injectors)

if one injector was putting too much fuel in you may see idle lean misfires as the other cylinders will now be lean with subtracting 30% or more fuel as your trims point out.
have a look in blocks 15/16

Avant Nate
03-03-2014, 11:07 PM
A quick question. The fuel trims seem to have settled down a bit, running -13 or so so at idle and bouncing around near zero at cruise. So it looks like the ECU is learning. My LTFT is at -5.5%.

So here's the question. My Coolant temp needle is dead center, but the reading using Torque and Vag--com will go as low as 82.5 C. So either my thermostat isn't maintaining 90 C, or my CTS is wonky. Would that account for some unusual fuel trims?