engine holding back ????

[AUDIS2avant]

Hi guys, am having problems AGAIN!!!!
This time it´s down on boost, and ewerything above 4500rpm it starts to have wery small misfires, just enough to feel it.
Boost is 1bar overboost faling to 0,6bar and i´m on homefries
Spark plugs are brand new bosch ones, and it dident help to change them.

What are the fault issues regarding MAF sensor?
How do i know if it´s broken down?
Hall sensor, cranck sensor, MFTS sensor and lambda is brand new and running on 99ron shell, and there is no boost leak.

Was testing last night, and it really has to struggle to come over 5500rpm, and top speed is reduced to 215-220km/h

[Parklife]

I've had that same problem. In my case it is infact a faulty MAF. The hot wire has an 'elastic' lifespan depending on the conditions under which it is used. Mine has lasted 13 years so i'm not complaining.

My modus machine picked up the fault code stating it was intermittent which it was. Under free reving of the engine, it picked up fine through the speed range (boost leaked off from WGFV under no load conditions) however when under load i.e driving fairly hard it feels like the spark/fuel/boost is being cut which can become quite violent. Infact this occurs when the ignition becomes intemittently heavily retarded as a result of MAF signal failure under loaded conditions.

After hearing stories of overboost cut off I decided to look deeper into the problem and analysed the MAF signal with a scope. Indeed under free reving conditions the signal rose and fell accordingly with no intermittent periods of signal interference or loss. The MAF also corrected accordingly when a change in air temp occurred (Hairdryer).

However under loaded conditions with the scope plumbed in (test drive) I found the MAF signal generated to loose output signal intermittently with no apparent cause other than degenerated electronics.

I know there are a veriety of faults that can cause these symtoms, but in my case the MAF was to blame, and not a boost leak/phantom engine knock causing boost cut.

As a result of a suddently retarded spark the boost generated will be leaked off unil the MAF signal has stabilized, at which point the boost will rise along with engine speed. A crazy kangaroo motion ensues.....

I hope this helps chap.

[AUDIS2avant]

Sounds exatly like my problem m8, so thanx for your input

Think i´m gonna order a new one from pete, along with an exhaust and some other sensors...

[urS6]

SNAP! Me too!

Thanks for the reply - just put new plugs in too - not gonna expect too much then until I get a new MAF

Where is the best place to get a MAF on-line - I am in deepest darkest Africa!

[urS6]

RS2 MAF Part numbers...?

Hi

I have the Audi Part Number as 034 133 471 N.

I believe that the Porche 968 MAF is the same part?

Can anyone confirm that Porsche 968 Part # 951 606 125 BX is correct?

It is about 25% cheaper from Porsche!!

Thanks