Originally Posted by Kevin

Do you have the stock air filter or aftermarket?

Your tune might be now in question.

How many miles do you have on your car?

Originally Posted by Macster

My info is in the event of a P0102 (mass air flow sensor -- below limit) the PSM is switched off. This probably accounts for the PSM warning light, and perhaps ABS too since the ABS and PSM systems are 'connected' in a way I won't cover here.

IIRC you're running a car that has had an Ecu reflash. I know nothing about these other than what I've read here and other places and that is some work beautifully and some can cause more trouble than they are worth. Your car may have a reflash that falls into the second category.

Also, the car has had its exhaust modified. Again I know nothing about these but what I've read here and other places: Some work just fine, while others are chrome headaches.

These latter exhaust systems may have a good sound, sell for an attractive price, they may even boost hp and torque but check engine light events due to 'sensor' issues is an unpleasant side effect.

These check engine light events may be due to the stock (or aftermarket) Ecu being unable to adapt/work with the different exhaust flow characsteristics of the engine with this aftermarket exhaust.

The position of the sensors in the exhaust gas flow is critical to their proper operation. Furthermore the performance of the converters is important too, because the #2 sensor is there to measure/monitor the converter's performance.

Some aftermarket converters simply may not have ability to provide a more open or freer exhaust gas flow and yet completely process the exhaust gases. The metals used in the converters are very very expensive so the natural tendency is to use less of them to keep costs down.

But a high flow converter almost has to have more of these metals since to be a high flow converter it would have a larger diameter or longer converter section which means a larger surface area whch of course must be coated with necessary metals to do the converting so I would hazard a guess all other things being equal a high flow converter would be more expensive since it should have more surface and thus a hgher content by weight of the expensive catalytic metals.

So, where does that leave you? Well, with too many unknowns. Questionable flash. Questionable exhaust system. And questionable any other mods that have been done to the engine.

Kevin's comments I think are spot on the money. You need to stop guessing and look at the engine data: MAF, O2 sensor, and so on and so forth. It is hard to say at this time what data will prove to be the most useful.

The times I've tried to track down problems with stock engines I've jumped from one set of sensor or derived data to another set and back again comparing and trying to understand the results to make an accurate diagnosis.

Sometimes I'm succesful. However at least once I made the wrong diagnosis (diagnosed a MAF when a leaking oil filler tube cap was the real cause of the error codes). But it was a mistake I paid for out of my own pocket.

Anyhow, without any sensor data any guess as to what is the problem is just that, a guess. But one you're not likely to know is the correct guess without spending a lot of time and money, your time or some mechanic's time (your money though) and money for parts.

As much as I would like to come up with an answer for you I'm unable to offer anything but to 2nd Kevin's recommendation/advice and get you to start looking at the sensor/derived data and post this and perhaps Kevin or someone else will spot something that they can pass on to you that proves directly helpful.

Sincerely,

Macster.

Originally Posted by jury_ca

BTW, agree with Macster, that if you are trying to diagnose a difficult condition, it is better to bring the car back to stock tune by reflashing the ECU to see if the problem with the MAF still exists.

Originally Posted by SSST

Slightly off topic, but can someone post a picture of the MAF location on the TT (stock air intake)?

Originally Posted by SSST

Slightly off topic, but can someone post a picture of the MAF location on the TT (stock air intake)? I've done some searches and found some good DIY threads, but all the pics are red-x'd.

Originally Posted by Dock

Are you trying to locate your MAF? If so, it is essentially under the left intake hose.