Tuning a '90 L98 engine
Melting Slicks
Joined: Jul 1999
Posts: 3,214
Likes: 101
From: Decatur, Alabama
There is a lot of good ideas and guessing here. Any and all could be correct. If you took the car to a dealer, they can pinpoint the problem if the tech was knowledgable and cared. For one, he can take the injectors out, they should have a injector driver tool (Kent Moore) and they can do a flow and pattern test of each injector in a glass jar and see how well and how much each injector sprays. Not a big job other than removing the plenum. I just hate to people spend money guessing at problem when there are ways to test them first. And BTW replacing the injectors will PROBABLY be the problem, but its nice to know first. Could also be in ingition system from plugs to distributor, also wont throw a code. Good Luck!
BTW IF and ONLY IF you decide you replace your bad stock injectors, I would like to have them to rebuild them for an NCRS project for a reasonable $
BTW IF and ONLY IF you decide you replace your bad stock injectors, I would like to have them to rebuild them for an NCRS project for a reasonable $
Last edited by corvette95; Feb 25, 2010 at 07:21 AM.
Burning Brakes
Joined: Mar 2009
Posts: 908
Likes: 0
From: CA
All excellent advice so far. I would also take a look at the IAC valve (Idle Air Control Valve). The pintle builds lots of carbon on it and can fall out of adjustment. You'll have to remove the throttle body to access it and remove it. Get some throttle body cleaner and spray it on the pintle liberally. Take a soft brush and work the carbon loose and spray again. Then adjust the pintle to the factory specs. Sorry it's been a while since I did this to my 91, but you can find the spec in a manual. I actually purchased a new one and installed it. It made a difference on how the car idled.
Thread Starter
Advanced
Joined: Oct 2009
Posts: 64
Likes: 0
Thanks for the info and advice. I spoke with the service rep yesterday and they hadn't yet completed the diagnosis. He said it could be the PCM, which was determined to be the culprit on another c4 they worked on. I should find out today. It's all still in limbo. Tks again....
