High Idle...need ideas - ZR-1 Net Registry Forums

LGAFF · 03-14-2009

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 · 03-14-2009

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 · 03-15-2009

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

bobbyhi · 03-15-2009

What rpm is the idle?

LGAFF · 03-15-2009

900-1000

Pete · 03-15-2009

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

Pete

-=Jeff=- · 03-15-2009

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 · 03-15-2009

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

-=Jeff=- · 03-15-2009

Quote:

Originally Posted by LGAFF

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

Ah, yeah.. probably

tccrab · 03-15-2009

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"

03-14-2009	#1
LGAFF Join Date: Mar 2007 Location: Crystal Lake, IL Posts: 7,194	High Idle...need ideas 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. __________________ LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359

03-14-2009	#2
rhipsher Join Date: Aug 2008 Location: Houston 90 Red ZR-1 Posts: 2,320	Re: High Idle...need ideas 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.

03-15-2009	#3
LGAFF Join Date: Mar 2007 Location: Crystal Lake, IL Posts: 7,194	Re: High Idle...need ideas My pump only kicks on for a few seconds every 5 minutes. __________________ LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359

03-15-2009	#4
bobbyhi Join Date: Jul 2005 Location: Mendota Heights, MN. 55120 Posts: 984	Re: High Idle...need ideas What rpm is the idle? __________________ Bob Anderson 1990 #2405 White/Gray Haibeck chip,4:09 gears,Power Effects Exhaust,5 spoke chrome,C5 brakes,49th Street rockers,K&N,Hurst,Headers,Upper & lower ported Minnesota State Director Founding Member #19

03-15-2009	#5
LGAFF Join Date: Mar 2007 Location: Crystal Lake, IL Posts: 7,194	Re: High Idle...need ideas 900-1000 __________________ LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359

03-15-2009	#6
Pete Join Date: Dec 2003 Location: Chicagoland,IL Posts: 2,679	Re: High Idle...need ideas Lee did you connect the little vacuum hose under the TB it's 1990 specific. Pete __________________ '91 #1635 PoloGreen 350 LT5 11.09 @ 129.27 11.04 @ 128.86 474RWHP 400RWTQ http://www.youtube.com/watch?v=SFNFOhGGlR4 http://www.youtube.com/watch?v=ZlRIOMwaDYY https://sites.google.com/site/peteszr1garage

03-15-2009	#7
-=Jeff=- Join Date: Jul 2007 Location: Bartlett, IL Posts: 7,169	Re: High Idle...need ideas 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 __________________ 1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978

03-15-2009	#8
LGAFF Join Date: Mar 2007 Location: Crystal Lake, IL Posts: 7,194	Re: High Idle...need ideas DRM chip, I think I am chasing a leak, just not in the usual vac lines. __________________ LGAFF 90 #966-150K miles-sold 92 #234-sold 1987 Callaway TT #17 1991 ZR-1 #1359

03-15-2009	#10
tccrab Join Date: Oct 2004 Location: Folsom CA Posts: 1,655	Re: High Idle...need ideas 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" __________________ TomC '90ZR1 #792 Honorary Pirate [B]If it ain't FUN, you're doing something terribly WRONG. [/B]