01 VW Jetta idling problems

Hey guys,

I have a 2001 VW Jetta 2.0 engine type automatic...76,000 miles

Recently ive been having problems with the car having serious idling problems when in park and sitting at a light; to the point that the car will stumble and stall. I replaced the fuel filter and gave it dry gas thinking I must have gotten bad gas or water in the tank. Worked for about a week and symptoms came back. Took the car to pep boys and got a full tune up with professional fuel system cleaning. Nothing happened and now it seems that the problem is worse and for some reason the turn signals are acting erradically (not sure if it is related at all). Check engine light is on. Once in gear and moving car runs smooth until stop. Catalytic converter was replaced about a year and a half ago and have had all oil changes on time with synthetic.

any direction you can provide me will be extremely appreciated

You're not the only one. I own a 1999 Jetta Gl 2.0L w/ an automatic and it has 118,000 miles. Occasionally, I have some idling problems with the vehicle stalling every once in a while. My Jetta also stumbles under acceleration from a dead stop to about 20 MPH, while the engine is cold. As I accelerate the engine drops down to idle and then jumps back up to a higher RPM for acceleration. Once the engine warms up the problem disapears. The MIL illuminates intermittently. The engine actually runs better with the light illuminated. I'mgoing to check the codes this weekend and post them once I find out what they are.

Go back to pep boys and have them read the codes for free and see what the codes are. IF the code is for system too lean or mass air flow sensor than replace the mass air flow sensor. ALso you can check the vacuum hose on the passenger side of the engine under the cover. It goes from the intake manifold to the fuel pressure regulator and commonly breaks causing rough idle and hard starts. You just pull up a little on the engine cover and the vacuum hose is right there.

The codes came back at:
P0102-Mass air flow circuit flow low input
P0300-Random misfire
P0301-Misfire on cylinder #1
P0302-Misfire on cylinder #2
P0422-Main catalyst efficiency below threshold
P1127-Bank 1 fuel adaption-system too rich

I replaced the mass air flow sensor about six months ago.

Now the car barely starts. I have to hold the throttle open for about a minute before the car will even idle. And the car wil still idle like crap. When the engine is cold the car won't have any real power until 4000 RPM. Even if I full throttle the motor, the car crawls very slowly up the revs till about 2000 and then the motors climbs a little faster till 4000. Once the car warms up there really is no problem except it doesn't idle evenly.

Has anyone heard of any software or hardware problems with the factory ECU that would cause the kind of problems my car is experiencing?

I often get the code for random cyclinder missfire and missfire in cylinder #3. After reading lots of posts I found someone with similar problems (mind you this only happens when its cold and wet outside), and he stopped his problems by changing out the Crank Sensor and the ECM. I am soon going to do the exact same cause I have replaced every part that has anything to do with Fire, Air and Fuel, the 3 main causes of bad idle. I See you also have random cyclinder misfires too....1st, if you have not replaced the coil, do that, I had a problem with it cutting out and that fixed that problem, then if that does not help or only improves slightly try the Crank Sensor and ECM. If you have done any or all of that and did not work, nevermind, I would then apparently have no clue what I am talking about :wink: . I hope that helps

my vr6 was having random misfires also, the codes i got were for idle air and for my mass air flow sensor, which none of them were the problem i changed my spark plug wires and it corrected my idling and misfiring. so change those first, get them from auto zone or oreillys and test it out first and if not take them back, and work your way down next would be spark plugs, then a maf