89 Corvette idleing rough.
Thread Starter
Navigator
Joined: Apr 2011
Posts: 9
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89 Corvette idleing rough.
I have a 1989 C4 tuned port injection. The intake manifold gasket was leaking so i tore it apart and replaced the gasket and had the manifold milled because it was warped.
It was able to be milled and fit the heads without a problem. When the intake and fuel injection was put back together it started great, however now it has a very rough idle and will stall out. It will always start, but will shake and idle rough if your not on the throttle...All the power is back from the original intake leak, but I cant figure out why the rough idle...probably rough runs up to 1800 1900 rpm before it runs good....any ideas?
The vehicle has been sitting awhile before i bought it, so i replaced the fuel filter, plugs, wires, cap and rotor. cant think of anything else....
help me out
It was able to be milled and fit the heads without a problem. When the intake and fuel injection was put back together it started great, however now it has a very rough idle and will stall out. It will always start, but will shake and idle rough if your not on the throttle...All the power is back from the original intake leak, but I cant figure out why the rough idle...probably rough runs up to 1800 1900 rpm before it runs good....any ideas?
The vehicle has been sitting awhile before i bought it, so i replaced the fuel filter, plugs, wires, cap and rotor. cant think of anything else....
help me out
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
As always, check for codes.
if no codes are set, then check for vac leaks. Unmetered air causes a pile of symptoms. This could be an EGR leak, stuck EGR, or shorted fuel injector. Is it rich? Pull a plug to see.
Finally, I forget, is the 89 MAF or MAP? either way, a code would set if that were an issue.
if no codes are set, then check for vac leaks. Unmetered air causes a pile of symptoms. This could be an EGR leak, stuck EGR, or shorted fuel injector. Is it rich? Pull a plug to see.
Finally, I forget, is the 89 MAF or MAP? either way, a code would set if that were an issue.
Instructor
Joined: Jun 2008
Posts: 173
Likes: 0
From: Norman OK
Ohm your injectors. You may have a few dead or leaking ones..
Pro
Joined: Mar 1999
Posts: 678
Likes: 0
From: Oslo, Norway
Hi. I had the same as you. Have you checked the this stiff brittle vacuumlines underneith the plenum. Have youchecked the tube from the MAF to the throttlebody. there may be some leakage difficult to see there.
When all is checked . >Do the minimum idle air adjustment and be sure that is alright. when doing that . be sure that you s\disconnect the ignition control a brown and white? cable with a connector at the firewall by the brake booster. If this is not disconnected the ignition tries to compensate when adjusting. There is a stream here in the forum you can search and the author is Lars Grimsrud. May be Vader has the same procedure in his good site.
When all is checked . >Do the minimum idle air adjustment and be sure that is alright. when doing that . be sure that you s\disconnect the ignition control a brown and white? cable with a connector at the firewall by the brake booster. If this is not disconnected the ignition tries to compensate when adjusting. There is a stream here in the forum you can search and the author is Lars Grimsrud. May be Vader has the same procedure in his good site.
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
If this happened right after doing the intake I would look at the things involved during the intake job..Maybe something wasn't put back correctly. Look for a vacuum leak also......WW
Last edited by WW7; May 1, 2011 at 09:24 PM.
Thread Starter
Navigator
Joined: Apr 2011
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every vacuum line during the intake job was checked extensivly, replaced some things that were worn out...but it now will stall once u place it into drive. It started idleing normal..than low, then will idle high around 1100 than drop down to 500...then once its in drive or reverse, it will stuble and most times stall.
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Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
every vacuum line during the intake job was checked extensivly, replaced some things that were worn out...but it now will stall once u place it into drive. It started idleing normal..than low, then will idle high around 1100 than drop down to 500...then once its in drive or reverse, it will stuble and most times stall.