Jason H

1 year and 10 months in my 2000 1.8T with no problems, just out of warranty (thanks to long commute) and now...

Yesterday I noticed that the car didn't have the kick that it did before, especially in 2nd and 3rd where you really notice the chip (GIAC). It definately wasn't in "limp" mode, in fact it still felt stronger than stock, just not up to it's usual chipped performance.

I needed gas so I went to my usual 76 station and made an even higher blend of 100/91 than usual, probably about 94.5 octane (usual is about 93-94). I get back on the freeway and about 3 miles down the road I get a CEL. Drive real cautious the rest of the way home. I have vag-com, but my laptop battery was dead. While charging it I searched the archives here. Amoung the remedies was checking the gas cap. I think "****, why didn't I remember that!" So I go out and I'll be damned it twisted to the left pretty easy. So I turned it until I hit 3 or 4 clicks. About a half hour later the laptop was charged and I hooked up vag-com. The DTC throwing the CEL was:

<b>17536 Fuel Trim Bank 1 Mult, System Too Lean 35-00</b>

I cleared it and did a throttle adapt for good measure. Then I took the car out for about 15 minutes. Not only did the CEL not come back the power was back too. Ok, hunky dory. I figured that the throttle must have gotten out of adapt, hence the power loss/return. and that the CEL was just my moronitude at the gas station.

I drove the car around a lot today and all still seemed well (I even checked for DTC's [none])untill I was in my parking lot at home. Then as I was parking the damn CEL came back! This time I hadn't noticed ANY loss in drivability before it came on. I still had the laptop in the car so I fired up vag com again and it is the same DTC. Now, yesterday I didn't remove the gas cap before screwing it tighter, I just turned it untill it clicked. maybe I didn't reengage the seal?

So there it is folks. I'd like some input. Is it likely to be residual symptoms of my loose gas cap, or was that just coincidental. Research here points to the MAF or less likely, the O₂ sensor if there is an actual physical problem. What measuring blocks can I run specifically to get a stronger diagnosis of where the problem is. If it is the MAF am I screwed since I'm (1,500 miles) past warranty? I've taken out and held the MAF from James R's car, so I know it's changable by myself. But how much does that bitch cost and does anyone know the calibration routine? If it's the O₂ sensor, how hard is that to get to, and is that bux or not? ANY advice/experiences welcome.

Lambo-Bully

also, you can check the MAF by monitoring channel 2, block 4. just revving the engine to redline should get up to 100+g/s, just a little less with the suspected vacuum leak you probably have.

96se

The MAF for my Saab (Bosh K-Jetronic) was $375 for a rebuild (new filament, reconditioned surfaces) .

O2 sensor will be on the cat, it'll take some wrenching if it wasn't put in with anti-sieze on the threads, but that'll be about a bill or so (what I've spent on them in the past) .

dingster

around .87 to .9. If it get's way below that during WOT, like .7 then you have a serious problem. Your car runs lean and the engine will cut power. Possible cause might be a leak between the turbo and the MAF or a bad MAF. low fuel pressure could also cause that. Check your fuel lines around the lift point and make sure they're not crushed.

James R.

Well looking at that trouble code...and checking with the old Bentley...it would see Audi agrees with pretty much all comments made so far with the exception of the MAF.

They suggestions are sorted in order of relevance...

O2 Sensor Pre Cat.
O2 Sensor Post Cat.
Fuel Pressure Regulator & Residual Pressure
Check Fuel Injector Function (Easy you have the tools)
EVAP Canister Purge Regulator Valve

Also it would be wise to test...

EVAP canister purge regulator valve -N80-
Wastegate bypass regulator valve -N75-

And I'm not sure, but I guess a trashed BPV could do this as well...though I think it would throw a charge pressure deviation code.

If you need any help just drop me a line...

Regards,

James

Jason H

;-) Check your mailbox!

Jason H

And yes I would practically beg for an Engineers help. Please.

Jason H

I did two runs. The first was longer, but I didn't save it properly here is the second run. I started easy in 1st and after shifting to second let the revs climb gently before going WOT and running up to about redline, going WOT again in 3rd briefly and then let it go easy in 4th before coming back down. If you all can give me your opinions. I logged groups 115 (for boost), 2 and 31.

I just let Excel save the HTML and then cleaned up the table slightly.

<b><u><A href="http://www.queenky.com/jasonh/101301.htm">Vag-Com data log</A></U></B>

dingster

Try loggin just block 31 and WOT in 3rd or 4th(longer sample period). The sample rate of VAGCOM with 3 blocks at the same time is terrible. I don't see any single reading of the O2 voltage in there under full boost.