201-A4

About a month ago I posted about a stumble that my car had only at 3k rpms when I would go WOT. Click <a href="https://forums.audiworld.com/a4/msgs/1917452.phtml">HERE</a> to see my previous posts.

Last night I had a chance to do some data logging, so I thought I would post my results to see if anyone had some additional insight.

Before I went out I cleared these codes:

5 Faults Found:
16806 - Main Catalyst: Bank 1: Efficiency Below Threshold
P0422 - 35-00 - -
17968 - Maximum Engine Speed Exceeded (Engine Warranty VOID! :-)
P1560 - 35-10 - - - Intermittent
17535 - Fuel Trim: Bank 1 (Mult): System too Rich
P1127 - 35-10 - - - Intermittent
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-10 - - - Intermittent
16688 - Cylinder 4 Misfire Detected
P0304 - 35-10 - - - Intermittent

When I came back from doing the pulls, there were no codes.

All logging was done in 4th gear.

I logged Block 002, 020 and 031

Block 020 showed no timing retard in the 2000-4000 rpm range.

The Maf looked to flowing plenty of air.
<img src="http://pictureposter.audiworld.com/38738/maf_all.jpg">

This plot shows the Injector time and Primary 02 sensor voltage. <img src="http://pictureposter.audiworld.com/38738/inj02.jpg">
Here you can see a dip in the injector time at 3k, that could correspond to the mixture going WAY lean.

What could be causing this very odd behavior?
If anyone has some insight to this problem, please let me know, I'm out of ideas.

TIA

volcom1875

dang thats strange, my car has done the same thing for about 3 months now. i have the apr stage III kit on and i cant even get 1 good pull. when im at like 3900-4200 rpm my car just pretty much bogs on me and feels like fuel is cutting out. i have not data loged the car yet but i have hoenslty tried everything new. new fuel pump,maf, n75, any much more worthless spending to solve nothing. im posting no solution but i am too with you with this problem so if you hear anything let me know, thanks : ) My aol Im Is Volcom1875

Afrosquad

What plugs are you running?

201-A4

You should really try to log some data, it will help answer a lot of you questions. Plus, It's much cheaper than throwing parts at the problem.
Ill shoot you an email if I find anything, no AIM over here.

volcom1875

Alright cool man , my email is osiris1875@hotmail.com thanks man (: see ya

QCRAZY

Have any timing and IAT plots??

201-A4

As I said in my post, timing retard was 0 degrees on all the pulls. Timing correction factors were also zero. As far a as overall timing goes, the ecu pulled back the timing about 2 degrees. The throttle plate was open a full 85.5 degrees the whole time. Ambient air temps were around 10F

Off the top of my head the data looked something like this:

RPMs Timing (degrees BTDC)
2600 13.0
2700 11.8
2800 10.1
2900 10.1
3000 10.2
3100 11.8
3200 12.5
3300 12.5
3400 12.8


IAT? Block 004, right?

201-A4

Could the mixture really get that lean? There is only 8% dip in the injector time @ 3k rpms.

Where is the fuel going?

Would this support the techs theory that the car is backfiring through the intake?

QCRAZY

Unless you use different O2 sensors, I've always seen that low voltage at WOT indicates RICH. If this is the case with your car you would be going really rich.

Since your fuel actually dips at this point I would say you are losing air somewhere. Adjusted your BPV's lately?? What's your boost doing in this range??

Otherwise, look for a leak elsewhere.

QCRAZY

See my post below....