High Idle Issue - ZR-1 Net Registry Forums

Hammer · 09-09-2007

I have had a high idle issue for about a week now. Last weekend I started the Beast and it didn't quite catch, ended with what could be called a backfire, but it was very small. Since then I have searched the forums for anything I could find and it appears a vaccum leak is imminent. I have replaced the common problem, the PCV connector (it needed it) but can't seem to see anything else loose or hissing that would cause this.
I start it and it will idle high at about 2000 RPM and slowly reduce to around 1000.

What else could be causing this issue? Does the Plenum need to come off?

Thanks

WB9MCW · 09-09-2007

Have you determined if your vac pump is constant on this would indicate a leak and pull to investigate further--sorry to say if that is the case.

lets see what the others say!

A26B · 09-09-2007

I'm assuming you've already checked the MAP sensor hose which is notorious for blowing off during one of those start/backfire events.

Hammer · 09-09-2007

Quote:

Originally Posted by A26B

I'm assuming you've already checked the MAP sensor hose which is notorious for blowing off during one of those start/backfire events.

That's what it is Jerry. I can see it blown off. I am going to atempt to get it back on without pulling the plenum. I'll post in a bit. Thanks

Hammer · 09-10-2007

Well I got the

Map Sensor

fuel evap system hose back on without pulling the plenum. I removed the aluminum cover over the throttle mechanism and then the fuel injector connection. This gives room to get a coat hanger in there and pull the hose on. There is what appears to be a metal ring around the hose. if you make a loop at the end of the coat hanger and bend it just right it's pretty easy (and ingenious I might add) to get it on.

High idle fixed.

09-10-2007

Quote:

Originally Posted by WB9MCW

Have you determined if your vac pump is constant on this would indicate a leak and pull to investigate further--sorry to say if that is the case.

lets see what the others say!

Vacuum pump would not run if vacuum leak is present in the manifold. It's only concerns are holding the secondary system at a 12" minimum.

John and you can slide your hand back behind the motor and grab a hold of the map sensor hose and connection with out removing anything. just make sure the motor is cool.

09-10-2007

Quote:

Originally Posted by Hammer

Well I got the Map Sensor hose back on without pulling the plenum. I removed the aluminum cover over the throttle mechanism and then the fuel injector connection. This gives room to get a coat hanger in there and pull the hose on. There is what appears to be a metal ring around the hose. if you make a loop at the end of the coat hanger and bend it just right it's pretty easy (and ingenious I might add) to get it on.

High idle fixed.

That hose is not for the map sensor. It's for the fuel evap system (if you are talking about the one that goes back under the front of the plenum.)

Hammer · 09-10-2007

Quote:

Originally Posted by Jeffvette

That hose is not for the map sensor. It's for the fuel evap system (if you are talking about the one that goes back under the front of the plenum.)

Thanks, that's the one. I think they must have put that little ridge around that hose for a reason.

I am still a virgin. Time will come soon. You and Rob will know cause the stuff'l (Plenum and Injector Hsings) come your way.

WB9MCW · 09-10-2007

So a fuel evap hose can cause high idle too? Two hoses that can come off and cause high idle--

who would have thunk it?

thnx for the correction Jeff--that is why I told him to wait to see what others had to say.

What would be another symptom of seconday system below 12" besides the constant vac pump running? Any performance issues if a leak in the secondary system?

09-11-2007

A small leak in the secondary system (pump cycling with the key in the on position and motor not running) will not cause any other symptoms. The engine provides the initial vacuum for the system and when the car is running the pump will be silent. If the leak is large enough the pump will come on when the secondary system is in use and it drops. The pump will come on and hold vacuum at 12".

09-09-2007	#1
Hammer Join Date: Apr 2006 Location: Ideho Posts: 2,653	High Idle Issue I have had a high idle issue for about a week now. Last weekend I started the Beast and it didn't quite catch, ended with what could be called a backfire, but it was very small. Since then I have searched the forums for anything I could find and it appears a vaccum leak is imminent. I have replaced the common problem, the PCV connector (it needed it) but can't seem to see anything else loose or hissing that would cause this. I start it and it will idle high at about 2000 RPM and slowly reduce to around 1000. What else could be causing this issue? Does the Plenum need to come off? Thanks __________________ [I][FONT=Comic Sans MS]John Boyd[/FONT][/I] [I][FONT=Comic Sans MS][SIZE=1]Ideho[/SIZE][/FONT][/I] [FONT=Comic Sans MS][SIZE=1][I]2015 ZL1 [/I][I]Camaro #1121 BLACK/BLACK 6 SPD (540 RWHP)[/I][/SIZE][/FONT] [I][FONT=Comic Sans MS][SIZE=1]1991 ZR-1 #458 [COLOR=red]RED/[/COLOR][COLOR=black]BLACK 72[/COLOR]k miles ([B][COLOR=red]SOLD[/COLOR][/B]) 1991 ZR-1 #473 [COLOR=red]RED/[/COLOR][COLOR=black]BLACK [/COLOR]37k miles ([B][COLOR=red]SOLD[/COLOR][/B])[/SIZE][/FONT][/I]

09-09-2007	#2
WB9MCW Join Date: Dec 2003 Location: McHenry, Il. Posts: 6,607	Re: High Idle Issue Have you determined if your vac pump is constant on this would indicate a leak and pull to investigate further--sorry to say if that is the case. lets see what the others say! __________________ http://i119.photobucket.com/albums/o...9mcw/SIG-2.jpg http://i119.photobucket.com/albums/o128/wb9mcw/vcm.gif "The Budget should be balanced, the Treasury should be refilled, public debt should be reduced, the arrogance of officialdom should be tempered and controlled, and the assistance to foreign lands should be curtailed, lest Rome will become bankrupt. People must again learn to work instead of living on public assistance." - Cicero, 55 BC " We the people are the rightful masters of both Congress and the courts, not to overthrow the Constitution but to overthrow the men who pervert the Constitution." - Abraham Lincoln

09-09-2007	#3
A26B Join Date: Dec 2003 Location: Arcadia,OK Posts: 3,394	Re: High Idle Issue I'm assuming you've already checked the MAP sensor hose which is notorious for blowing off during one of those start/backfire events. __________________ Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 *ZR-1*, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed.

09-10-2007	#5
Hammer Join Date: Apr 2006 Location: Ideho Posts: 2,653	Re: High Idle Issue Well I got the Map Sensor fuel evap system hose back on without pulling the plenum. I removed the aluminum cover over the throttle mechanism and then the fuel injector connection. This gives room to get a coat hanger in there and pull the hose on. There is what appears to be a metal ring around the hose. if you make a loop at the end of the coat hanger and bend it just right it's pretty easy (and ingenious I might add) to get it on. High idle fixed. __________________ [I][FONT=Comic Sans MS]John Boyd[/FONT][/I] [I][FONT=Comic Sans MS][SIZE=1]Ideho[/SIZE][/FONT][/I] [FONT=Comic Sans MS][SIZE=1][I]2015 ZL1 [/I][I]Camaro #1121 BLACK/BLACK 6 SPD (540 RWHP)[/I][/SIZE][/FONT] [I][FONT=Comic Sans MS][SIZE=1]1991 ZR-1 #458 [COLOR=red]RED/[/COLOR][COLOR=black]BLACK 72[/COLOR]k miles ([B][COLOR=red]SOLD[/COLOR][/B]) 1991 ZR-1 #473 [COLOR=red]RED/[/COLOR][COLOR=black]BLACK [/COLOR]37k miles ([B][COLOR=red]SOLD[/COLOR][/B])[/SIZE][/FONT][/I] Last edited by Hammer; 09-10-2007 at 07:26 PM.

09-10-2007	#9
WB9MCW Join Date: Dec 2003 Location: McHenry, Il. Posts: 6,607	Re: High Idle Issue So a fuel evap hose can cause high idle too? Two hoses that can come off and cause high idle-- who would have thunk it? thnx for the correction Jeff--that is why I told him to wait to see what others had to say. What would be another symptom of seconday system below 12" besides the constant vac pump running? Any performance issues if a leak in the secondary system? __________________ http://i119.photobucket.com/albums/o...9mcw/SIG-2.jpg http://i119.photobucket.com/albums/o128/wb9mcw/vcm.gif "The Budget should be balanced, the Treasury should be refilled, public debt should be reduced, the arrogance of officialdom should be tempered and controlled, and the assistance to foreign lands should be curtailed, lest Rome will become bankrupt. People must again learn to work instead of living on public assistance." - Cicero, 55 BC " We the people are the rightful masters of both Congress and the courts, not to overthrow the Constitution but to overthrow the men who pervert the Constitution." - Abraham Lincoln

09-11-2007	#10
Jeffvette Guest Posts: n/a	Re: High Idle Issue A small leak in the secondary system (pump cycling with the key in the on position and motor not running) will not cause any other symptoms. The engine provides the initial vacuum for the system and when the car is running the pump will be silent. If the leak is large enough the pump will come on when the secondary system is in use and it drops. The pump will come on and hold vacuum at 12".