RomRaider

Hey everyone, I have been trying to troubleshoot an issue causing my car to keep dropping my IAM. The car is a 98 impreza with a 06 WRX swap that has ~90k miles. The motor is mostly stock except for it uses the 98 impreza intake, Walbro 255 fuel pump, has the secondary air pump deleted (turned off codes), throttle plate/requested torque table are modified to be more linear, and the OL/CL delays are changed to 0. I have been running this setup for over 30k miles with not issues.

The first thing that I notices was a slight hesitation between 2500-3000 RPM, I took a learning view snapshot and it showed that my IAM had dropped.

This is what I have tried so far:
-changed fuel filter
-tested fuel pressure regulator
-checked spark plugs
-did compression test --> 120,117,115,112 (cold)
-looked for intake leaks (found and fixed one in brake booster tube outside check valve)
-looked for sources of false knock ( found a loose heat shield and secured it)
-cleaned MAF

Most recently my car had been maintaining a IAM of 1 for almost a full tank, I was logging the car and noticed when I turned on the A/C the IAM dropped. I looked at the compressor and found the bearing felt a little chunky so I removed the belt and reset the ecu. The IAM dropped again...

There are no CELs except for a periodic P2021 (Left TGV position) that pops up randomly. I'm planning to 'fix' that soon, but it doesn't seem like it is related to this issue.

I was planning to check for boost leak next, but I am not optimistic about finding a problem there since my fuel corrections look ok.

Here is a log of normal driving after the ECU was reset following the A/C
http://datazap.me/u/edayvie/tgv-cel?log=0&data=2-6-10
Unfortunately I was logging the last time the IAM dropped
Here is one 3rd gear pull from a little while ago. It seems like most of the knock events the ecu detects are pretty lot load, but it does happed at high load too.
http://datazap.me/u/edayvie/3rd-gear-pu ... 0&data=2-6

All my learning views show timing being pulled from all over the place


Here is a list of a few knock events that were recorded up until the IAM dropped last time.

KNOCK DETECTED at 2015-08-17 05:38:15 PM
AFR: 14.8
Boost (psi): 0.00
Boost Target (psi): -1.8
FKC (deg): -1.41
FLKC (deg): -1.05
Fuel correct (%): -0.5
IAM: 0.438
Injector PW (ms): 5.4
Knocks: 10
Load (g/rev): 0.92
MAF (g/s): 38.61
RPM: 2516
Speed (mph): 58.4
TGV left (V): 0.34
TGV right (V): 0.36
Throttle pedal (%): 18.0
Throttle plate (%): 22.4
Timing (deg): 32.0
Turbo WGDC (%): 0.0

KNOCK DETECTED at 2015-08-17 05:37:59 PM
AFR: 14.4
Boost (psi): -2.80
Boost Target (psi): -6.4
FKC (deg): -2.81
FLKC (deg): 0.00
Fuel correct (%): -3.6
IAM: 0.438
Injector PW (ms): 3.8
Knocks: 6
Load (g/rev): 0.64
MAF (g/s): 28.99
RPM: 2713
Speed (mph): 62.8
TGV left (V): 0.34
TGV right (V): 0.36
Throttle pedal (%): 12.5
Throttle plate (%): 16.9
Timing (deg): 41.5
Turbo WGDC (%): 0.0

KNOCK DETECTED at 2015-08-17 05:37:34 PM
AFR: 14.5
Boost (psi): 0.90
Boost Target (psi): -0.4
FKC (deg): -1.41
FLKC (deg): -1.05
Fuel correct (%): 4.7
IAM: 0.438
Injector PW (ms): 5.9
Knocks: 0
Load (g/rev): 1.05
MAF (g/s): 38.36
RPM: 2189
Speed (mph): 52.8
TGV left (V): 0.34
TGV right (V): 0.36
Throttle pedal (%): 23.1
Throttle plate (%): 28.2
Timing (deg): 27.5
Turbo WGDC (%): 4.7


Anyone have any ideas what might cause this? I want to start tuning my car but I need to sort this out first.

Thanks

Also one example of the typical learned values I'm seeing.

A few more questions.

-My Fuel Trims are not perfect but within +-5, so I am assuming that my MAF is not the culprit, is that an accurate assumtion to make?

-My starting IAM is .5 and the step value is .25, but sometimes it changes to a value that is not a multiple of .25, like .688. How does the ECU calculate that value? I've notice if the IAM steps by the step value it normally recovers pretty fast, but once it changes to a different value it seems to get stuck there for a longer period?