Ive been having two issues with my GLI lately, last week while driving on the parkway my car just randomly lost acceleration, no lights came on but the gas peddle was unresponsive. I was able to restart it while coasting and thought nothing of it. Then it kept doing it. It was raining that night but ive never had an issue before. Other times it dies it is sunny out. The second issue is sometimes when I hit over 10lbs of boost the car will start to misfire and run like ****. No CEL's come on the dash but if we scan it with VAGCOM it says theres misfires happening, obviously. Already did a smoke test and there are no vacuum leaks. Anyone have some input? Thanks!
If you are positive about no vac/boost leaks, then it's likely a sensor.. I'm thinking maf, tps, or primary O2, maybe crank/cam.. When you scanned it, the only codes present were for misfires? Nothing else?
Do you have access to an actual Vagcom? If you do, you need to go to the screen where you can see the airflow rates... It shows the MAF readings in grams/second (i believe), so see what the number is at idle, then blip the throttle, it should increase.. If it doesn't, you have a bad MAF
So my shop took a look at it and ran some logging but the car was not acting up and all the logs showed correct values, hope someone else can chime in or I guess we have to wait until its actually doing it to log it again?
i recently had a very similar issue, replaced the MAF again (replaced it in oct.) and fixed it. ran like **** especially when boosting, couldnt get a code besides misfires. the 1st time the maf messed up though my traction control light would flash. this time nothing... but id try that. what kinda air filter are u using? oiled filters such as K&N are really bad for the MAF on these cars... Good Luck!
ya it may, when mine went out the 2nd time i unplugged for 2 days while i was waiting on the new one to come in and it ran fine without one, but be careful it could cause it to run lean. but you can def. unplug it and see how it acts.
i had my k&n on for several months before it caused any problems... after i realzed what was happening i just went and bought a cheap Spectre filter from oriely's. a filter is a filter really. but once its used up il prob replace with AEM dry flow.
I had an issue like this on my gli, after replacing everything mentioned above I replaced the fuel pump and that fixed it.
well my buddy looked into the car more for me the other day and said the fuel pressure at the rail was about half of what it should be indicating the fuel pump is bad, so were gonna replace that next week and hope thats the problem
I had this same EXACT issue last week. I smoke tested it, checked for codes, replaced the maf, fuel pump and the n75 valve and then finally after two weeks of this crap the car finally threw a code. Cylinders 1 and 3 were miss firing so i replaced all the spark plugs and coil packs on 1 and 3 and she runs like a dream again!
The first thing I would replace is plugs and coils. Replace all of them if it hasn't been done in the last 40k. It's just preventative maintenance. Throw the old working ones in the glove box for when another takes a crap.
You can also try simply cleaning the MAF (with MAF cleaner).
Log misfires to see if it's coming from the same cylinder(s) each time. If 2 of the cylinders are experiencing constant misfires I wouldn't be surprised if the car shuts down. I personally never experienced that. This will at least shed some light if it's specific cylinders (which would point me towards an ignition problem) or all of them randomly (which I may consider fueling issues then).
What about your fuel filter, when's the last time you replaced that? Do it every 40k. It's cheap.
These are the most common issues. If you have already addressed these simply ignore this post.