MKII Jetta Idling like crazy

[Russell]

Quick run down of the problem that I am having... I start the car up and it will idle up and down fluctuating between 4000 to 500Rpm and finally settle at around 1000Rpm. When I am driving the car it seems to be fine but as soon as you get into stop and go traffic the car gets me sweating. For example if I have to give it some gas to move up half a spot and then put on my breaks the car will go up to 2500Rpm and when I put on the breaks it will all my stall out (which it did in front of Bow Valley Square last night at 5:45pm in rush hour traffic). Any suggestions for what to look at? This car really owes me nothing as it was $1000 and has lasted just about a year now but if I can keep driving it I will.

[longsock]

Re: MKII Jetta Idling like crazy

have you checked the microswitch?

[Russell]

Re: MKII Jetta Idling like crazy

not to sure where "the" microswitch is... any more details on this item?

[Russell]

Re: MKII Jetta Idling like crazy

So I did a little searching and I figured out that you were talking about the 'full throttle microswitch'... where is this located on the car?

[longsock]

Re: MKII Jetta Idling like crazy

under the throttle body

[Russell]

Re: MKII Jetta Idling like crazy

Would it be the ISV?

[Russell]

Re: MKII Jetta Idling like crazy

Not sure if anyone knows anything about this but someone suggested the "blue" sensor coming out of my coolant housing. Anyone know if this is the "blue" sensor? Also I am assuming this is my ISV?

[Tuna]

Re: MKII Jetta Idling like crazy

that is your ISV yes.

I thought that sensor in the coolant bottle just measured level and gave the flashing warning when it was low. I could be wrong though.

Can't remember how to diagnose ISV's I thought you could unplug it, it would cause it to idle like crap but wouldn't cause the idle spike. I've had to mess around with a couple of them.

Vortex may be your friend on that one.

[bonfire]

Re: MKII Jetta Idling like crazy

Could just be a dirty ISV. Take it out and clean it, see what happens.

That or it could also be cracked.

Although we did have a similar problem with our Mk1 Cabby, and it was a vacuum leak, it would idle all over the map between 600-1200. Give it the beans and it would either hesitate, or quit.

Get a can of ether and while the car is running just give a light spray around some of the vacuum lines. If the idle increases suddenly then you have a vacuum leak.

In fact a vacuum leak sounds more promising, as stop and go traffic causes a fair bit of fluctuation in vacuumm, especially with the braking and the vacuum to the brake booster.

[Russell]

Re: MKII Jetta Idling like crazy

This maybe a stupid question but where do the vacuum lines run?

[bonfire]

Re: MKII Jetta Idling like crazy

Now to be honest, I have never worked on a Mk2.

Just my Mk1.

But if they are similar there should be a few leaving the intake mani, a bigger one going to the Brake booster (driver side big round disc). One going to the vacuum resi hanging from the hood (I think that is Mk1 only though).

[Kor]

Re: MKII Jetta Idling like crazy

Could the throttle body be sticky?

[newfie_veedub]

Re: MKII Jetta Idling like crazy

is it a digi or cis car? def. sounds like a vaccum leak. you can buy the lines from c-1 for $6 a meter.

[Russell]

Re: MKII Jetta Idling like crazy

where would one get a can of ether from?