2001 Jetta, little diagnostics help needed.

jasondart · #1 (**permalink**) 11-19-2009, 12:56 PM

I am trying to fix my wife's 2001 Jetta, AZG engine, 80,000 miles. I have always been a do it your self kind of guy and recently changed out brakes, sway bar links, spark plugs, wires and a few other odds and ends, but I am running into a problem. Check engine light has been on for some time.

I recently replaced the ignition coil. I had brought it to a shop to have the codes read and they could duplicate the VERY bad misfiring when there was moisture in the air with a spray bottle. Instead of paying the $485 they wanted to charge I decided to do it myself. I purchased the coil from Autohausaz. It was about $100 less than the dealership.

Glad I did, because the original one had huge cracks in it, which would explain the major problems with moisture. At the same time I cleaned the mass air flow sensor.

Now the engine will not down shift (automatic). Highway speeds (65 mph) brings the RPM up over 5500. I put back in the old coil to see if that was it, but it did not change a thing. I am thinking the mass air flow sensor is completely shot or I ruined it cleaning it (used mass air flow cleaner). I am about at my wits end and will probably bite the bullet and bring it to the dealership, pay the money and get it fixed for good.

What would cause the engine to not down shift?

slappy · #2 (**permalink**) 11-19-2009, 01:34 PM

I had a car in the past that did the same thing and it was a vehicle speed sensor on the transmission.

jasondart · #3 (**permalink**) 11-19-2009, 01:40 PM

Quote:

Originally Posted by slappy

I had a car in the past that did the same thing and it was a vehicle speed sensor on the transmission.

I could see that, though it just seemed odd that it started happening immediately after I changed out the ignition coil and cleaned the mass air flow sensor. I will check into that.

jasondart · #4 (**permalink**) 11-19-2009, 03:21 PM

Just an update...

Took it to Autozone had the codes read. Turns out that the computer needed to be reset. Something must have happened when I disconnected the battery. Good news I found a local shop that works on VWs and they fixed the computer issue for free, with a scan tool. (Gave them a gift certificate to a local restaurant for their help.) Needless to say, I will be going back there for sure. I wish more local shops would help out with problems like this.

slappy · #5 (**permalink**) 11-19-2009, 06:23 PM

Glad to hear it.

05GTI1.8T · #6 (**permalink**) 11-19-2009, 11:52 PM

Quote:

Originally Posted by jasondart

IWhat would cause the engine to not down shift?

bad transmission control module. either that or the valve body is sticking in ur trans we replace those often at the dealership i work at common problem.
it could be a number of things but those r the two that come to mind first.

edit: i just realized i read the first post then replied didnt even bother to read the rest lol

MOEZER · #7 (**permalink**) 11-20-2009, 09:54 PM

wow i had this happen to me when i disconnected my speed sensor on the trans but hell it wouldnt shift to 4th gear or shift down to 2d and 1s so i replaced the speed sensor and it didnt help!!! then i was so pissed that i was riding the car like a hore lol then i started to play with my criuse control switch and took it up to about 6000 RPms and then it fixed it self lol