J. Patterson

That is certainly possible but a bad mass airflow sensor should also initiate a check engine light and a stored code. Be careful though to get one that is specific to your engine model. An example is this one for an AMU. I have bought a couple of them from Pure Motorsports through the years. ( along with all of my suspension and brake upgrades)
It sounds like your's problem is minor but you really need a good independent mechanic who specializes in VW Audi. At least you need access to VAG com and someone experienced in its use. Good luck I wish I could help more.

carolhern

Well, I changed the MAF with one I purchased at the Audi dealership. But its still not boosting correctly even with that one.

According to the Audi Tech, I had the code for MAF and O2 sensors. I thought it would trigger O2 sensor if the MAF was bad, or the fact that i ran the car with the MAF unplugged two days before taking it to the dealer. I changed the MAF, have run it now for 300 miles and no change. I plugged in an OBI II and have no codes. So not sure what to think at this point or what to look for.

carolhern

If anyone knows where I could take the car in the San Francisco Bay Area, I'd greatly appreciate the info.

carolhern

Here is what the Audi Tech wrote:

Road tested and verified loss of boost. Scanned for codes and found 3 codes P1555 maximum charge pressure intermittent P1114 B1S1 internal resistance too high. P0102 Mass air flow low input. Checked B1S1 O2 sensor and resistance and found open circuit between terminals 1&2. Recommend O2 sensor. The rear O2 sensor needs to be replaced and front O2 sensor needs to be rewired because the harness is laying against the exhaust manifold. Checked turbocharger system. check for intake exhaust leaks and found none. Smoke checked intake exhaust leaks and found none. Smoke checked intake sytem and found no leaks at this time. Checked vacuum hose routing and found ok. Checked boost cutoff valve and found ok. checked Mass air flow. Found connector will not hold. Secured and took for road test monitoring block values and found will not reach max spec. Disconnected mass air flow and road test. Found vehicle runs at normal operation. recommend mass air flow and o2 sensor and re-evaluate concern.

So from this report, I changed the MAF. I show no codes and wonder if I should change the O2 or not.

carolhern

Changed the O2 sensors today. See how it goes this week.

carolhern

So yesterday when I went took off to work in the morning, the car boost and drove EXCELLENT. I thought FINALLY back to normal. But by the time I hit slow traffic in my morning commute and pulled into work 30 miles later...it was back in the limp mode type of feeling.

So whatever it is...it seems to run fine for a bit, then go back to what seems to be limp mode and no boost.

J. Patterson

The list of diagnostics you copied from the dealer sounded pretty detailed and thorough. It's really hard to know much more from a distance but their opinion that the mass airflow sensor was the heart of the problem sounds plausible. I had one years ago that was marginal and would cause the car to intermittently go into limp mode and display a lean code.

carolhern

I changed the MAF already, when there was only temporary improvement, I then changed the O2s this weekend. But even then it limped.

J. Patterson

Need to run a log on that MAF to check its output. Do you have VAG Com?

carolhern

No I dont have a vagcom. Maybe its time I purchase one. Do you suspect that the new MAF is defective?

I originally purchased one at O reillys. I thought something was wrong with it so I then purchased a $200 one from Audi dealer.

i wonder though about the cable that runs from the MAF to the ECU. I dont know if it makes a difference...but when I changed the MAF, I noticed that the connector doesnt "click" into place. It goes on but it seems to lack some kind of securing " click". The connector doesnt move or come off so maybe that doesnt matter.