MarkChai

Hello -

The DTC:
17535 - Fuel Trim; Bank 1 (Mult): System too Rich
P1127 - 002 - Lower Limit Exceeded - MIL ON

It has come on twice in the past couple weeks, usually after highway driving and then a period of cruising at 45-55 mph.

I recently replaced the fuel filter because I was getting a lean code and a weird air-compressor sound when starting the car up. That sound is not totally gone, but much quieter. I also replaced two coilpacks and all four spark plugs due to misfires.

I did have this problem when I got the car 1.5 years ago and never found out why, but I figured it was due to the K&N that was installed. I switched to paper filter, cleaned the MAF, and everything was fine.

I published the logs online:<ul><li><a href="http://spreadsheets.google.com/pub?key=ppWjvlY4gOsXkRbZTAV4ePQ">Spreadsheet at Google Docs</a></li></ul>

diagnosticator1

The OE parts are dark blue colored.

MarkChai

Yes, they are the dark blue OEM injectors, part #0280156065

cparke

We may be in the same boat.

When I clear all learned values, initially a misfire may happen as the computer begins learning that bank 1 is too rich. Might the cylinder that happens on be suspect as a bad fuel injector?

I think your compressor sound might be the evaporative system. I get that noise (very quiet though) sometimes after the car is parked. Opening the gas cap makes it go away but it naturally goes away after some time too. Maybe your noise is different, however.

MarkChai

I just don't know how to interpret the VAG-COM logs to see if there's any info in there that may indicate what the issue is.

cparke

Could be:
1) MAF - need to do another redline test, this one properly with a steady throttle right through 6800 rpms. Suspect my MAF is giving erratic values---false air would cause too rich condition.

2) Fuel injectors - cloggy and more fuel comes in than is requested. Someone else here found they got a too lean code after fuel cleaning, turned out to be MAF for him so far.

3) Intake/vacuum leaks - air gets in or out after the MAF and screws up the air-fuel mixture in the cylinders. Not sure entirely how this is supposed to lead to a too rich condition (I'd expect too lean), but apparently there is a way.

4) N75, EVAP or some other valve not working properly?

MarkChai

Not to mention we have different motors.
I'm a B6 A4 AMB motor code 1.8L turbo, you are a
B5 A4 2.8 V6...
On that note, are you sure your V6 has an N75 valve? I thought that regulated boost on turbo motors.


RE: MAF readings
The highest your MAF reading went in your log is 115 g/s at 6280 RPM. That does seem low.

The highest mine went was 148 g/s at 5680 RPM. I don't know if that's low or not.

cparke

Yes, I have an AHA engine, that's true they aren't the same engine, but the fundamentals behind this problem are still the same.

No, I'm not sure that I have an N75.

I'm not strictly looking at MAF readings, but if I have multiple problems, I have to systematically resolve them starting with MAF. I don't think I did the redline test right, you can tell how the RPM and engine load rises &amp; falls.

If MAF passes when I do the test right (or I still have the richness problem after replacing it), air/vacuum leaks would be the next thing I'll be looking for, followed last by fuel injectors (which has always been suspect since this may have started with fuel cleaner). What else could it be in what otherwise appears to be a good running car?

Besides MAF logs, up until now I've also been looking at block 32 and 55. However, I suspect I should be looking instead at block 20 and 31 going forward.

<a href="https://forums.audiworld.com/a4/msgs/2300223.phtml">Vag-Com Data Logging FAQ...</a>

MarkChai

My timing does look a little weird based on the VAG-COM FAQ though.

MarkChai

Stock software, no chip or flash. Stock K03 Turbo.