ESL

I brought my car in today for an oil change and to have the mechanic check the turbo frequency valve code which the engine was throwing. The frequency valve is shot and will be changed out on Thursday. When I was driving home and getting on the highway the car was noticably quicker for about 3-4 seconds then it would hesitate and drop acceleration as if the rev limiter was hit but it happened at 4K rpm. At the same time I heard a sound from the drivers side of the engine that sounded like air being released. Is it the diverter valve? Something else? What should I tell my wrench on Thursday?
Thanks in advance,
Eric

PS I did use the search first.

tar6day

Sounds like a boost pipe leak. Check your connection at the intercooler since he had to take it off in order to get to the frequency valve.

ebaker

Check the MAF too.

ESL

Thanks for the suggestions. To ask a newbie question, what is the MAF and what does it do? In reading the archives (133 threads) I think I understand it has something to do with the air coming into the engine or I may be totally wrong. The MAF is referred to a lot but never really defined.
Thanks,
Eric

Felix

MAF = mass airflow sensor - it's shortly after the air filter (therefore on the low pressure side of the intake) and measures the amount of air being drawn into the engine. If it's providing a false reading engine performance can suffer.

Rassel

http://en.wikipedia.org/wiki/Mass_airflow_sensor

ESL

Thanks Phelix and Rassel!

bertmerv

Please post what is determined to be the cause. I have the same problem, but it is very infrequent.

ESL

I will I promise.

ESL

The boost pipe was loose. Fixed when they replaced the frequency valve.
Thanks all.