View Full Version : won't hold idle

03-11-2008, 09:47 AM
I tired searching a few things but didn't come up with much. The car is a 98.5 1.8T and it won't start on its own. What I mean by this is I have to give it some gas for it to even start and if I don't keep giving it gas, the car immediatly dies. I took it for a short drive down the road like that and found that theres a sucking/whistling noise when its under load. When I pulled back into my driveway after this 3 minute drive, the car would hold idle at about 400-500 rpms.

I'm new to german cars (well I guess I'm pretty new to cars in general) but I have more time than money to spend so I'd rather not take it to a mechanic. Thanks for any help.

Also, there is no CEL, but I could take the car to autozone to have it scanned.

03-11-2008, 10:01 AM
Don't even get me started on idle problems. I have had enough of them, my car is in the shop right now hopefully getting my idle problems finally fixed. The only thing at the moment I can tell you to do is to do a Throttle Body Alignment with vag-com or a v-checker. Take it to the dealer if you don't have either on of them or find someone in your area who does and then go from there if that doesn't work then welcome to my world.

03-11-2008, 10:04 AM
check all your vacuum lines - if you have a leak, idle would be greatly affected.

03-11-2008, 10:40 AM
Thanks guys, I'll check the vac lines and see if I can get a hold of a vag-com. I guess I forgot to mention that on my drive, when I would shift, The engine wanted to die until I caught the next gear and it woud jerk back to life. I'm not sure if that helps any but it can't hurt to add.

03-11-2008, 10:45 AM
has it had cam belt tesioner replaced? As a siezed one can "hold back" an engine from ticking over properly.Hard to diagnose on the interweb obviously,lol

03-11-2008, 11:07 AM
I'm not sure if it has or not as I just bought the car back in September. I could look through all the records though.

03-11-2008, 11:12 AM
like snapr said... vac lines are key.

If you have a vac leak big enough to keep you from idling, it will throw a P0171/P0172 but maybe not right away. It doesnt sound like you've been able to drive it enough for it to trim that much fuel.

Check everything, TIP, TOP, FPR, and all the vac lines connecting to the IM.

03-11-2008, 11:30 AM
check the intercooler piping. If you hear a whistle under the car that probably means that one of the intercooler piping has come off and your hearing the turbo trying to create boost. Jack up the car and check the rubber piping coming from the turbo and into the front frame assembly.

03-11-2008, 07:36 PM
you have a boost leak, do a search for boost leak tester...

03-15-2008, 12:32 PM
Thanks for the help everyone. I did a boost leak test using this diy --> http://a4mods.com/index.php?page=webcontent/pages/boostleak.html .

I was expecting air to come gushing out of somehwere, but I only found one tiny little leak. I was looking for about 20 minutes and only lost about 5 psi on my 50 gallon compressor the entire time. Would a small leak like this cause my problems?

Anyway, I'm going to the dealer to see if they will scan my car for me and to see if I can get a new hose for that leak.

03-15-2008, 01:48 PM
Okay I'm pretty sure its not the boost leak thats causing me problems. On the plus side, the car will hold idle at about 650 rpms after its been warmed up for a few minutes. The VW dealer closes at noon on Saturdays so no luck there.

On my 30 minute drive I noticed a few more symptoms. I floored the car in 3rd gear and it was even slower than normal. It felt like I was trying to go up a hill in 5th gear under 2k. Also, you know how a car will jerk if you let off the gas quickly in 1st gear? It was jerking like this at times in any gear if I slightly let off the gas or got on it. Finally, the biggest problem I found is that occationally when I would let off the gas to shift gears the rpms wouldn't fall, but they would keep racing towards the redline until I caught the next gear. (people kept looking at me like I was an idiot lol) And the sucking noise I heard was coming from the passager side under acceleration so I think it was just air being sucked into the intake.

If you have any ideas I'd really appreciate it if you tossed them around here. Thanks again.

03-17-2008, 01:21 AM
have you checked the MAF sensor?