High Idle...need ideas

[LGAFF]

Well, I pulled the plenum put it back together, had a vacuum leak.....vac would not hold on the line running from the D/S center of the plenum. Found a leak in the hard line, pin hole, fixed it....put it all back together and still have high idle.

Vacuumm holds on both the pass/driver side plenum inlets. Also vac is holding on the line running from the pump to under the plenum.

Any other ideas, PCVs seem to be sealed. I did replacet the breather hoses, maybe I should check there first.


I also swapped the new IAC form my 92 and no help.

[rhipsher]

I wonder if your check valve is stuck. But if your check valve is stuck your vacumm pump would be running constantly so I'm not sure. Unpluging that drivers side hose from the plenum will definately cause high idle. And that line goes to the check valve.

[LGAFF]

My pump only kicks on for a few seconds every 5 minutes.

[bobbyhi]

What rpm is the idle?

[LGAFF]

900-1000

[Pete]

Lee did you connect the little vacuum hose under the TB it's 1990 specific.

Pete

[LGAFF]

yup, got that one, everything is connected, car idled well before I tore into it....however gaskets had to go as they were leaking oil.

I will take a look tomorrow, and try a spray bottle to check leaks.

[-=Jeff=-]

what PROM is in the car?

my 90 did the same thing, was fine when I bought it, but when I R&Red the plenum last year I had that problem.. I had an OEM variation in the car, I switch to the later version for better IAC steps and it seemed fine

[LGAFF]

DRM chip, I think I am chasing a leak, just not in the usual vac lines.

[-=Jeff=-]

DRM chip, I think I am chasing a leak, just not in the usual vac lines.

Ah, yeah.. probably

[tccrab]

I had a lot of problems getting the funky two pipe PCV connector just behind and under the throttle body to seal up. I chased leaks there for ages. Hair spray finally did the trick. Pull the hoses back, wipe them clean, give them a light squirt then plug them back in.

Good luck!!

TomC
"Crabs"

[Jeffvette]

Lee, what all did you replace while under the plenum?

[LGAFF]

Coils
Breather hoses
obviously gaskets

[Jeffvette]

Coils
Breather hoses
obviously gaskets


Did you remove the fuel rail?

[LGAFF]

Yes, are you thinking the 0-rings did not seat?

[Jeffvette]

Yes, are you thinking the 0-rings did not seat?


Bingo. Check for tears as well.

[LGAFF]

Looks like I will be tearing into the plenum again next week........battery also **** out today!

Other than that, things are going well.

[jonszr1]

on that block connection for the pvc sytem that goesjust behind the throttle body .i had a problem sealing mine also . what i did was find 2 short pieces of thin way flexable hose to hook up both line and the leak problems were gone