87' 5.7L Suburban Issue - The 1947 - Present Chevrolet & GMC Truck Message Board Network

shultzee13 · 01-09-2012, 01:17 PM

Replaced all the wires.
Replaced all the plugs.
Replaced the cap & rotor.
Replaced the muffler & tailpipe!
Replaced the MAP sensor.
Replaced the Ignition Coil.

Problem - It surges sitting at red lights with foot on the brake. Doesn't do it in drive. It is surging forward like it wants to go.
What in the world could it be? I thought it might be one of the problems mentioned above but it's still doing it.

HELP or suggestions would be much appreciated.
Thanks Eric

gchemist · 01-10-2012, 02:24 AM

Remove and clean the air idle valve. It's probably staying open a bit at idle. By surges, do you mean engine RPM? If so check, for a vacuum leak. Check the brake booster line to the intake. Check all the other small vacuum lines too.

shultzee13 · 01-10-2012, 10:23 AM

Quote:

Originally Posted by gchemist

Remove and clean the air idle valve. It's probably staying open a bit at idle. By surges, do you mean engine RPM? If so check, for a vacuum leak. Check the brake booster line to the intake. Check all the other small vacuum lines too.

Thank you I will try that.

shultzee13 · 01-11-2012, 12:47 PM

Can someone tell me were the air idle valve is located on this vehicle?
Thanks.

shultzee13 · 01-11-2012, 12:48 PM

I googled it but no such luck.

DirtyLarry · 01-11-2012, 02:23 PM

I agree, the IAC is the place to start. It is located on the passenger’s side of the throttle body. It has a square connector. As you stand in front of the engine and look down on the throttle body, it is located at about the 10 o’clock position.

There is a good chance you have a vacuum leak some place as well. My 89’ had the same surge going on at idle also. I found several vacuum leaks where the vinyl tubing was cracked but ultimately found an intake leak at the passenger’s rear corner of the intake. My Burb project.

gchemist · 01-11-2012, 03:07 PM

Sign up at www.autozone.com. The maintenance section has great factory info on location and part replacement.

ChevyTech · 01-11-2012, 07:44 PM

I think another thing you should be doing is testing the fuel pressure with the engine running.

Mr.Chevy4x4 · 01-11-2012, 08:38 PM

I agree, it's either going to be the idle air valve, or I have also seen a bad EGR valve or EGR solenoid cause the same surge.

01-09-2012, 01:17 PM	#1
shultzee13 Registered User Join Date: Jan 2012 Location: Tyler Texas Posts: 223	87' 5.7L Suburban Issue Replaced all the wires. Replaced all the plugs. Replaced the cap & rotor. Replaced the muffler & tailpipe! Replaced the MAP sensor. Replaced the Ignition Coil. Problem - It surges sitting at red lights with foot on the brake. Doesn't do it in drive. It is surging forward like it wants to go. What in the world could it be? I thought it might be one of the problems mentioned above but it's still doing it. HELP or suggestions would be much appreciated. Thanks Eric

01-10-2012, 02:24 AM	#2
gchemist BAD BOW-Silverado XST Join Date: May 2000 Location: Senior Member from Austin, TX Posts: 6,431	Re: 87' 5.7L Suburban Issue Remove and clean the air idle valve. It's probably staying open a bit at idle. By surges, do you mean engine RPM? If so check, for a vacuum leak. Check the brake booster line to the intake. Check all the other small vacuum lines too. __________________ Gerardo a.k.a. Mad Chemist Silverado XST videos

01-11-2012, 12:47 PM	#4
shultzee13 Registered User Join Date: Jan 2012 Location: Tyler Texas Posts: 223	Re: 87' 5.7L Suburban Issue Can someone tell me were the air idle valve is located on this vehicle? Thanks.

01-11-2012, 12:48 PM	#5
shultzee13 Registered User Join Date: Jan 2012 Location: Tyler Texas Posts: 223	Re: 87' 5.7L Suburban Issue I googled it but no such luck.

01-11-2012, 02:23 PM	#6
DirtyLarry Windy Corner of a Dirty Street Join Date: Jun 2003 Location: Pueblo West, Colorado Posts: 2,926	Re: 87' 5.7L Suburban Issue I agree, the IAC is the place to start. It is located on the passenger’s side of the throttle body. It has a square connector. As you stand in front of the engine and look down on the throttle body, it is located at about the 10 o’clock position. There is a good chance you have a vacuum leak some place as well. My 89’ had the same surge going on at idle also. I found several vacuum leaks where the vinyl tubing was cracked but ultimately found an intake leak at the passenger’s rear corner of the intake. My Burb project. __________________ Current vehicle collection: 1978 Chevrolet K10, 8.1L, NV4500, NP205 1989 Chevrolet Suburban, 8.1L, NV4500, NP241 1993 Chevrolet C1500 Sportside, TBI 7.4L, 4L60E 2001 Chevrolet K2500HD, Ext Cab, SWB, 8.1L, ZF 6 speed 2014 Chevrolet Impala LTZ 3.6L Vortec 8.1L because life is too short to tolerate underpowered vehicles Instagram

01-11-2012, 03:07 PM	#7
gchemist BAD BOW-Silverado XST Join Date: May 2000 Location: Senior Member from Austin, TX Posts: 6,431	Re: 87' 5.7L Suburban Issue Sign up at www.autozone.com. The maintenance section has great factory info on location and part replacement. __________________ Gerardo a.k.a. Mad Chemist Silverado XST videos

01-11-2012, 07:44 PM	#8
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,621	Re: 87' 5.7L Suburban Issue I think another thing you should be doing is testing the fuel pressure with the engine running. __________________ For those of you that are wondering why you are not getting replies to your thread: Did you give the model, year, engine, fuel system type, and transmission information? If it is modified from what came stock from the factory, let us know that too.

01-11-2012, 08:38 PM	#9
Mr.Chevy4x4 Registered User Join Date: Jul 2007 Location: Sims, NC Posts: 531	Re: 87' 5.7L Suburban Issue I agree, it's either going to be the idle air valve, or I have also seen a bad EGR valve or EGR solenoid cause the same surge. __________________ All things Chevy truck: 1986 SWB "Jolene" boosted 5.3/4l80e project



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