Bad MAF...Hopefully?

[a4ms6_hayden]

I own a 2002 Audi A4 Quattro 1.8T Tiptronic. I am speeding up onto the freeway and once i am about to merge over to the right most lane at about 50-60ish MPH in 3rd (revs are about 4-5K) and the car starts sputtering and cuts power. i slow down and restart the engine, its running horribly. thought i was running it out of gas since i had about 10 miles left and the on ramp was a fairly sharp turn. I barely got it back up to 45mph to get to my nearest gas station. i filled it up and drove it about halfway home before it started running perfectly again. once home, i let the car idle for 20 minutes to see if the issue came back and it didnt. fast forward a couple hours when i go to drive the car again, the issue comes back. rough idle, and wanted to die when i came to a stop. I unplugged the MAF and the car ran better without it.

I have had the issue of the EPC and ESP coming on and losing all engine power during normal driving, but have always reset it by restarting the engine.

The car has red top coil packs from a C6 A6, its tuned by ECA Concepts, has a splitter DV, gutted cat, and muffler delete.

[Ozone510]

Anecdotally speaking when I've had an issue like this, it was due to a FAT boost leak and I've gone through the motions of wishful thinking about MAFS and BS like that. I'd look at all your charged air connections, and anything past the MAF, like TIP. Unplugging the MAF just puts you into a MAP based "Safe" mode that will neglect any leak because it's injecting fuel based on pressure seen close to the intake manifold. So if it's running good after unplugging, then your leak is probably well before the MAP sensor.

Again, this is anecdotally speaking, you could have a very small problem, or maybe even a bad MAF. But a good place to start is inspecting the TIP, which usually crack after so many miles and heat cycles.

Good luck and feel free to update here what you find to help the next unlucky person lol

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[a4ms6_hayden]

that is EXACTLY how it seemed to be running, as if air was being brought in after the MAF. Even when i drove the car with the MAF unplugged to get back home it had a severe lack of power in the top end, so much so it couldn't rev out in 2nd. 2.5k-3.5 was where the power was at.

Will try to get a smoke test done tomorrow. Will post findings and results.

[Ozone510]

A lot of the time, you can just use your ears to locate these leaks since the ECU can deal with small leaks and adjust AFR accordingly. This sounds like a big enough leak to detect using simple means, but if you can easily check with smoke, obviously you will find exactly what you need.

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[EuroxS4]

Check MVB 32 for Maf readings. My money is on the MAF,failing crank position sensor, failing SJP or a failing PCV or broken vacuum hose or line.

[a4ms6_hayden]

SJP is less than a year old on this car. Will check MAF readings and CPS readings, also do a smoke test as well today.

[a4ms6_hayden]

Update: Smoke tested the car and found 1 single leak after the MAF. It was the pancake valve on TIP for the PCV. I sealed the leak and it did not solve the issue.

I hopped into OBDELEVEN and the following codes came back;

P1335 - Engine Torque Monitoring 2
Control Limit Exceeded
Status: Intermittent

P1560 - Max. Engine RPM exceeded
Upper Limit Exceeded
Status: Intermittent

P1388 - Ctrl. Module Faulty
Implausible Signal
Status: Intermittent
(heard this code has to do with the DBW)

Sprayed the MAF down with some MAF cleaner, put it back in and took the car for a drive. Looking at live data, measure block 3. it says the MAF reading is 0G/s for most of the drive, but sometimes the MAF reading would randomly come back at random readings. Every time the MAF reading came back, the car would run horribly.

Something i also noticed throughout the drive, while looking at measure block 3 is that the throttle angle was at 0% the entire drive.

[EuroxS4]

I would say wiring or ecm issues.maf readings at idle should be 3-4 g/s and higher during acceleration. I would also check ecm ebox for water intrusion.

[a4ms6_hayden]

Seemed to have found the issue. Tossed a new MAF in today and it did not fix it. Took a closer look at the wiring at the MAF connector and saw that almost all the wires had their insulation flaked off and were touching one another. I de-pinned the connector and slid some heat shrink over each wire as a band-aid fix. Took the car for a drive and it ran fine. Just ordered a Doorman pigtail connector to fix it properly. Will give one last update when i install it tomorrow to for sure tell whether this was the issue or not.

[a4ms6_hayden]

MAF wiring connector was indeed the issue. Wired in the new pigtail and the issue has gone away.

[Gin+]

Nice work!