1991 Jetta GTX 16v

[BaggedGLI]

Hey I know a bunch of guys (and girls?) on here have lots of knowledge about older vw's and your help would be greatly appreciated.

I just bought this car a couple weeks ago and it has a really rough idle.

I have replaced the spark plugs, battery and adjusted the timing slightly but it still idles really rough.

I'm trying to figure out the problem so here are some symptoms:
-idle is random
-sometimes when i give it some gas while its idling then let off, it just stalls
-sometimes it takes a long time to start, sometimes it starts almost instantly
-when i put my foot down while driving it like backfires and hesitates then pulls
-it has aftermarket ignition wires

Any ideas what could be leading to the rough idle?
I'm thinkin of changing the fuel filter and i want to check and clean the maf sensor (dont know where it is)
found a couple wires/a smakk ground that needs to be fixed as it is frayed.

Thanks for the advice.

[VWSM]

Re: 1991 Jetta GTX 16v

you don't have a maf sensor,you have throtlle switches and a potentiometer for the
air box lift plate.
check your intake boots for tears in the rubber.
don't use platinum plugs.
you have to set your fuel mixture to zero milliamps plus or minus one fluctuating.
make sure your fuel regulator is dark black and not grey.
if you have a throttle body with an idle screw it's wrong..if it does make sure it's turned in all the way.
pull your throttle open and listen if you can hear the throttle switches clicking.
any oil inside the distributor?
pull on those rubber boots while the car is running.
cheers hope this helps.

[p951]

Re: 1991 Jetta GTX 16v

You have a vacuum leak, classic symptoms. Check all of the rubber boots/lines/hoses under the hood, you'll most likely find a tear. From your description it sounds like it's a pretty big leak too.

[BaggedGLI]

Re: 1991 Jetta GTX 16v

Well when i replaced the plugs i put in platinum plugs, and that seemed to smooth it out a little and now its worse than ever

What is the problem with running platinum plugs?

[BaggedGLI]

Re: 1991 Jetta GTX 16v

How would i go about setting my fuel mixture to zero milliamps?
I did see a screw on the throttle body and it seemed to be out quite a ways, i will try tightening that up.
Ill check the distributer, its covered in oil, i think i might need to replace the seal.
Also another symptom that i forgot to mention is that when i start it up and rev it a little it sprays what looks like water out the exhaust, but it leaves a residue that doesnt dry and isnt flammable.

Thanks for the help

[BaggedGLI]

Re: 1991 Jetta GTX 16v

Bump for help?

[VWSM]

Re: 1991 Jetta GTX 16v

you need a multimeter and a bypass harness to the fuel pressure regulator.

this fuel system is very touchy..and they require multiple adjustment's.
next to God nobody knows them better than me.
Shoot a pm.
Is the vehicle driveable??

[BaggedGLI]

Re: 1991 Jetta GTX 16v

pm sent

[BaggedGLI]

Re: 1991 Jetta GTX 16v

This goes out to anyone, is 1mm-2mm of play in the distributer shaft normal.

I dont know if that made sense so, the part of the distributer that spins. 1mm-2mm normal?