Very HIGH Idle After Timing Belt Swap 1991 3.4L Z34

[Rabbi]

completed the timing belt today, I Quadroople checked everything. Everything was aligned perfectly. Now i started my car and it idles high. It hits the rev limiter and just loops. Its idleing way to high, Im thinking its trying to idle at about 4000 RPMS


what the hell would cause this? I did everything perfectly, Could i maybe of swapped a couple plugs wrong or something? That wouldnt cause high idle would it??????


I also had a little trouble getting the egr valve back on the plenum, I Replaced the gasket though. But i hear no leaks so i dont belive this is the problem.

anyone have any ideas?


should i recheck the cam flats?






note i ran the car with the drivebelt very loose, so maybe it wasnt getting full coolent flow? I Dont think this would have anything to do with anything,since i only ran the car twice for maybe 30 seconds each

[Rabbi]

also the first time i started it i smelling a slight burning smell, But it went away quickly. I Dont know if this is a symptom of anything but god i just went though hell with my tbelt and the last thing i need is a burned piston ring or some shit.




also about the spark plug wires, i really dont see how i could of hooked one wrong, They only reach to a certain point, So im 90% sure these are correct.


ALSO i ran the car without the air filter & hose on it while i test started her. Im not sure if this has anything to do with it, But im scared to start my car back up again,so i dont want to test it with it on lol.

[Rabbi]

another update. I Put the air box back on, And it does the same thing.

But i found something intresting out.

in park it hits the 3000rpm rev limiter and keeps trying to break it.
but
AS SOON as i put it in park
it drops to a PERFECT 2000 rpm's and stays there.


the car sounds good in drive, But something is really wrong here. Im really leaning away from the timing belt. I Dont think it would idle this high unless the timing was WAY off, And i did it by the book, The crank mark may of been SLIGHTLY off, but it was DAM CLOSE if it was off.


anyone have any ideas? im desprate!

[Rabbi]

another update. I was told by a mitsubishi mechanic (very reputable in the mitsu tuning scene) that if its idling 2000RPM higher than norm its a vacume leak. This coming from a mitsu mechanic, But still he knows his stuff.


anyway heres a picture,the silver hose i DO NOT have period. What the hell is it?

and the other hose, blue box & arrow , i think i have this hooked up wrong. Is this supposed to feed to the other side of the plenum and under the engine identification cover? Because thats where mine goes.




also my front exaust pipe is hot as hell after about 10 seconds of running the car.

[dk05]

I have no idea what may be causing the high idle, but I would say the mitsu guy is right that it is some kind of leak. As far as the hoses go, the silver one is for the brake booster, it goes to the back side of the plenum. The one in the blue box is the hose for the pcv valve, it is hooked to the right spot BUT it does not look like it is hooked up correctly, the pvc valve is not in the larger hose all the way, which it should be. The lip on the top should be flush with the larger hose. Try using a longer piece of hose off the plenum. As far as the exaust pipe getting hot that is very normal, just try not to touch it, haha.

~Dk

[OldSkoolGP]

if you did a timing belt swap, you should have put on a new upper intake manifold. If you didn't I'd say there's your leak. To confirm it, spray some brake cleaner on the seam between the upper and lower with the engine running. If the engine changes pitch when yuo do that, there's your leak. Otherwise double check your brake booster hose on both ends. Someitmes it comes loose from the booster.

[Doubt_Incarnate]

my 2.8 did something like this. i swapped a hotter cam in and it would barely idle, once i would convince it to run, the idle would eventually climb way up around 2500rpms. all new gaskets and hoses, never found any leaks. never could time the distributor to get the right timing it was always advanced. i wonder if you didnt get the cam timing correct in the dohc if they could be part of the problem.

[Anonymous]

I doubt an intake manifold gasket would cause an idle that high.

You probably forgot the brake booster line, I used to do it EVERYTIME.

It is on the backside of the plenum, almost underneath. It is pretty hard to see, but if you look closely, you'll see it. There should be a preform rubber line going from the brake booster to the intake manifold. You probably forgot to hook this up.

[Rabbi]

brake booster line was hooked up properly

brand new upper intake gasket was installed along with a brand new egr gasket



anything else to check?

why would it drop to 2000 after i remove it from park

where is the other end of the brake booster hose ??

[OldSkoolGP]

The brake booster hose connects to the back of the plenum, it'a big 5/8" hose connector and you can't miss it if you have the intake off. Seeing as how you don't know what it is, I'd give 10:1 odds that's your problem.

[Rabbi]

The brake booster hose connects to the back of the plenum, it'a big 5/8" hose connector and you can't miss it if you have the intake off. Seeing as how you don't know what it is, I'd give 10:1 odds that's your problem.

noooo .... where's the OTHER end connected? that peice is connected perfectly and tight as hell on the back underside of the plenum.

[SappySE107]

Cam timing won't cause this high of an idle, period. It has to be a vacuum leak or the TPS is messed up, the throttle plate is stuck, or satan has possessed your car. Vacuum leaks are the most common problem with high idle. Check your PCV tubing, as its another thing that gets overlooked.

[Doubt_Incarnate]

if you booster feed line is connected at the plenum, the other end would connect to... the booster.

[OldSkoolGP]

It's kind of hard to miss where it connects, since the hose is form fitted. Just look on the booster, which resides behind the master cylinder. Check that connection and push on it to make sure it is on there tight.

[Rabbi]

fixxed

very small unplugged vacume line


yay for normal idle!