1986 Surging issues
Thread Starter
Heel & Toe
Joined: Aug 2013
Posts: 17
Likes: 0
From: San Diego California
That is where I will start. I will pull the TB and IAC. Do a tune up and go from there. Thanks to everyone that is helping with this. I just got my used wheel speed sensor in the mail as well. They quit making that part and I finally found one from a guy in florida on ebay.
Doc
Doc
Team Owner
Joined: Jul 2004
Posts: 28,363
Likes: 3,255
From: Hartford WI
That is where I will start. I will pull the TB and IAC. Do a tune up and go from there. Thanks to everyone that is helping with this. I just got my used wheel speed sensor in the mail as well. They quit making that part and I finally found one from a guy in florida on ebay.
Doc
Doc
Thread Starter
Heel & Toe
Joined: Aug 2013
Posts: 17
Likes: 0
From: San Diego California
Alright its been a little bit. I replaced the TPS and took the IAC out and cleaned it. It was caked with black soot. Bought a new TB gasket kit and did it all. It is still surging and now I am just frustrated. Its going to the dyno shop tomorrow. I just want to drive this beast. If anyone has anything else they think might help please chime in.
Thanks!
Thanks!
Thread Starter
Heel & Toe
Joined: Aug 2013
Posts: 17
Likes: 0
From: San Diego California
I was going to just replace the IAC and the TPS but figured I would start with the CTS because I noticed it was broke when I started pulling the TB. Cleaning the IAC I figured would be good enough. IDEAS?
Heel & Toe
Joined: Mar 2013
Posts: 22
Likes: 0
From: Peoria Arizona
Alright its been a little bit. I replaced the TPS and took the IAC out and cleaned it. It was caked with black soot. Bought a new TB gasket kit and did it all. It is still surging and now I am just frustrated. Its going to the dyno shop tomorrow. I just want to drive this beast. If anyone has anything else they think might help please chime in.
Thanks!
Thanks!
Drifting
Joined: Mar 2013
Posts: 1,952
Likes: 239
From: Venice Cali.
I did a few things to stop the surging. But after fixing something it is a good idea to unhook the battery to reset the computer.
To fix the surging I put a new 02 sensor, fixed my iac pigtail(the rubber shrank down and the wires were contacting each other thus shorting the iac temp sensor)
I put some ac delco plugs(r43 I think). Cleaned all connectors.
Then I set idle adjustment. It just stopped surging.
A tip When setting tps sensor to .54 leave the voltmeter connected and as you tighten it if the voltage goes crazy(bad body) it is bad, because my new one stays right at .54 as I tighten it.Then of course rotate and make sure volts climb to 4.3 or somethin like that.
To fix the surging I put a new 02 sensor, fixed my iac pigtail(the rubber shrank down and the wires were contacting each other thus shorting the iac temp sensor)
I put some ac delco plugs(r43 I think). Cleaned all connectors.
Then I set idle adjustment. It just stopped surging.
A tip When setting tps sensor to .54 leave the voltmeter connected and as you tighten it if the voltage goes crazy(bad body) it is bad, because my new one stays right at .54 as I tighten it.Then of course rotate and make sure volts climb to 4.3 or somethin like that.
Last edited by xrav22; Oct 24, 2013 at 09:57 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
Racer
Joined: Dec 2012
Posts: 347
Likes: 25
From: Rockford Illinois
I don't know if the 86 is like my 85 but if it is, follow the black hose from the PCV valve. It should go to a metal pipe that goes into the plenum. The rubber that seals the connection gets loose with age. I had a huge vacuum leak there and just wrapped a zip tie around it and pulled it tight. I had a surge and cut off situation before that made me stop driving the car. I just got in a few minutes ago and had perfect 550 rpm at idle all night long.
Thread Starter
Heel & Toe
Joined: Aug 2013
Posts: 17
Likes: 0
From: San Diego California
Ya I just got a call from the Dyno Shop and they found the issue. Its the one things that I didn't do because I got frustrated. The O2 sensor. My IAC was filthy was well. I cleaned that and checked all vacuum hoses. Found a couple that were cracked and repaired them. Its good now. Moving on to the next phase of bringing it back to the glory of 1986
Thread Starter
Heel & Toe
Joined: Aug 2013
Posts: 17
Likes: 0
From: San Diego California
It ended up being a bad O2 sensor and a dirty IAC. Combine that with a couple cracked vacuum lines and a cracked TPS tip and what do you get. PROBLEMS
Thanks to all you guys for walking me through this headache. Now moving on to other areas to bring this HotRod back to life with all its luster!
Doc
Thanks to all you guys for walking me through this headache. Now moving on to other areas to bring this HotRod back to life with all its luster!
Doc
Heel & Toe
Joined: Mar 2013
Posts: 22
Likes: 0
From: Peoria Arizona
I'm glad you solved your problem. We found out why ours was surging. It was the hose that provides vacuum to the brake booster. The fitting on the engine was loose and needed about 1/16 of a turn to tighten it up. My husband also replaced the squeeze clamp that held the hose on the fitting because it was weak. Car runs great again.