1994 hard start, hard idle

[oregoncoast]

Just bought a jetta...GREAT deal on it.
Started right up...but the previous owner said that SOMETIMES it will turn over and over and over....but not start.

Last night, after detailing it, I went to move it and it did just that....wouldn't start.....and possibly because it was still warm???
Because when I got up this morning after sitting all night it started RIGHT up again.

Please!! Any direction or ideas would be good....don't really know where to start and this may be a notorious problem with 1994 Jettas?

Thanks!!
Scott

[oregoncoast]

So after a few days of testing I have found out a bit more.

I left the Jetta at my girlfriends house....she put it in the garage.
Started in the morning fine. She tried starting throughout the day and all was well...purrs like a kitten.

Then I came over and not only started it but DROVE it to get it warm.
I came back to the house...turned it off....then back on.
It starts....idles up then WAY down....then evens out.
But it sort of idles rough.....rpms skipping up and down slightly.

I let it sit for about 4 hours and figured for sure it would start now that it is cooled down.
No....it didn't start.

So my thoughts of this being strictly a heat based issue may be wrong?

Can a faulty ignition switch cause this problem?
How about fuel pump issues?
And what about the cooling sensor?

Any idea where I can get a diagram of where the cooling sensor is since I can probably replace this myself without much hassle....if I know where it is?

[oregoncoast]

........got up this morning and it started RIGHT up again.

Please....any ideas?
So confusing.

Runs SO good when it starts.

[Doug Tatham]

It sounds like your idle stabilizer needs to be cleaned. When you first start up, the idle is controlled differently, but when it heats up, the stabilizer valve kicks in. I've used carburator cleaner in the past to clean it. Remove it and look inside and you'll see a piston inside. Clean it thoroughly and make sure it slides up and down freely. This should fix the problem.

[oregoncoast]

Thank you so much!
I will check into that.
Do you know of a photo of the stabilizer so that I know what it looks like.
I didn't get a manual with the car.

Thanks!
Scott

[Doug Tatham]

It's the cylidrical metal thing in forward and above the valve cover. It has a couple hoses attached to it and an electrical connection. It's about 3-4 inches long and 1 1/4 or so inches around. It has to be removed when you take the tube off that connects the throttle body to the breather. One hose connects to the intake manifold (right side) and the other hose connects to the intake tube.

[blinskta]

OMG i have EXACT same problem. cant fig it out for the life of me.! my secret is if i unhook power batt terminal and rehook (get ready for alarm noise) then my car starts up. but in mornings boom starts, while warm its fine. between like 3-8hrs sitting wont start! same problem man ill go check out my idle stabilizer hope that helps me out too! post any other ideas for us guys! i cant belive we might have finally solved this mystery!

thanks!

[Doug Tatham]

The idle stabilizer was suggested as a fix for rough idle. The won't start when warm thing is likely the ignition coil or it could be one of the temperature sensors.

[oregoncoast]

Does the ignition coil act differently when sitting in the sun than warm from running?
The car starts fine after running for 30 minutes....it is ONLY sitting still in the hot sun that makes it not start.

I can imagine how a coolant temperature sensor could permit a car from starting when the sun is on the hood of the car and heating up the coolant in the radiator(which is the only time it doesn't start).....but does this explain why is still starts fine when I have driven the car for 30 minutes???

Does the coolant get warmer sitting in the sun than it does while driving and circulating through the radiator??

Thanks for your feedback.
Any thoughts??

[Doug Tatham]

Does the coolant get warmer sitting in the sun than it does while driving and circulating through the radiator??
__________________________________________________ ____________

Not yet, but with global warming, maybe in the future.

When you said that the car didn't start when hot, I thought you meant that it didn't start when it had been running for awhile and the engine was hot.
This is a long shot, but try removing each of your fuses and gently clean the contact on the fuses and the fuse box with 400 grit sandpaper. The other possibilty is wiring, but I really can't make any other guesses.