2001 Volkswagen Jetta 01 Jetta -- performance issues

reenay3644 · Posted at Fri Mar 06, 2009 8:50 pm

Engine Performance problem
2001 Volkswagen Jetta Two Wheel Drive Manual 145000 miles

I have an 01 Jetta 1.8 Turbo Wolfsberg edition with 145000 miles, manual. Today when I got off the interstate (approximately 30 miles) the car began drive very rough and the check engine light came on and began to blink. The vehicle makes no noises while at a stop, but when acceleratng the vehicle drives extremely rought (almost as if it is going to turn off) and then you will hear a slight woosh (air) sound when it is time to switch gears. Once the woosh sound is heard the car drives slightly better until the gear needs to be changed again. Once in about fourth gear the car drives much better with only a little vibration. Again, once stopped at a light or parked there are no obvious vibrations or noises. I did notice a slight burning smell when I got out of the car, but saw no smoke or where it could be coming from when the hood was lifted.

later in the day I went to autozone and pulled the check engine code. P0172. My usual mechanic said they would have to look at the vehicle but wont be able to for a while.

I would like to know the best possible cause since fixing this particular model Jetta is EXTREMELY expensive.

Thank you!!!!!

renee

Zackman · Posted at Sat Mar 07, 2009 4:52 am

reenay3644 · Posted at Sat Mar 07, 2009 8:37 pm

Thank you for your response, but I did have the codes pulled originally. I was told to start with the MAF sensor, then "try" the o2 sensors, and eventually if all else failed replace the fuel injectors. The MAF and injection coils were replaced approximately six months ago, which pretty much leaves the o2 sensors and fuel injectors. My only concern is I just purchased the vehicle (dummy me), put $1400 worth of repairs in it a week ago, and now this.

With the symptoms I gave, is it possible to pinpoint the most likely choice? Could a mass air flow sensor possibly go bad after being replaced 8 months ago?

Also, I just had the fuel injectors cleaned today with no benefit to the "symptoms."

AGAIN, THANKS!!!!!

Zackman · Posted at Sun Mar 08, 2009 12:28 am

Do not replace more parts unnecessarily. Any vehicles, MIL P0171 (lean condition) or P0172 (rich condition) has to do with fuel/air mixture. While MAF (measures air flow) seems to be the best candidate, it has always been the 4th, maybe 5th in the line to be checked. Same thing with O2 sensor. Air leak has always been the first thing to check (especially with turbo-charged vehicles). The next has always been fuel holding the correct pressure.

The diagnostic chart that I posted came off Mitchell.

This one came from VW Technical Service Bulletin.

The best way to diagnose is to go back to the dealership. They are better equipped to properly diagnose the trouble than most shops out there. But that doesn't mean a regular tech cannot work on it, except they will take a little longer without proper equipment. Have your mechanic follow the diagnostic chart.