1990 ZR-1 Misfire Carbon'd up 2 & 7, BLM 115 at idle - ZR-1 Net Registry Forums

J & J Speed Shop · 07-23-2013

Looking for some help or something that I missed. I am working on a 1990 Corvette ZR-1. The vehicle originally came in and the dual mass flywheel was banging like crazy at idle. I ordered the brand new injectors from FIC and replaced both the primaries and secondaries. The idle misfire was greatly improved and 4-5 injectors were bad 3-4 ohms and about 3-4 were questionable under 10 ohms. The vehicle has new spark plugs, coil and oxygen sensors. There is still a slight miss at idle BLMs rich at 115 and INT around 89-94. If I drive the car down the street it is fine at part throttle, but once you try to go WOT in normal power mode the car falls on its face misfires like crazy and will not clean up. Turn the switch to full power mode and it will stumble for a split second and then accelerate normally. I have already checked fuel pressure, and I have spark with a tester on all cylinders including 2 & 7. Did a compression 215 psi and leakdown and everything checks out. If I pull the plugs they all look normal except 2 & 7. Both of these plugs have a good amount of carbon buildup. I also saved the old plugs I removed before I started this job and noticed 1 plug from each bank was more carbon'd then the rest of the plugs. I don't know weather it was 2 & 7 but I assume it was. At first I was thinking maybe I received 2 bad primary injectors but the plugs before the injectors kind of ruled that out in my mind.

I was thinking maybe a bad ECM ?? Suggestions please help

07-23-2013	#1
J & J Speed Shop Join Date: Jul 2013 Location: Western New York Posts: 4	1990 ZR-1 Misfire Carbon'd up 2 & 7, BLM 115 at idle Looking for some help or something that I missed. I am working on a 1990 Corvette ZR-1. The vehicle originally came in and the dual mass flywheel was banging like crazy at idle. I ordered the brand new injectors from FIC and replaced both the primaries and secondaries. The idle misfire was greatly improved and 4-5 injectors were bad 3-4 ohms and about 3-4 were questionable under 10 ohms. The vehicle has new spark plugs, coil and oxygen sensors. There is still a slight miss at idle BLMs rich at 115 and INT around 89-94. If I drive the car down the street it is fine at part throttle, but once you try to go WOT in normal power mode the car falls on its face misfires like crazy and will not clean up. Turn the switch to full power mode and it will stumble for a split second and then accelerate normally. I have already checked fuel pressure, and I have spark with a tester on all cylinders including 2 & 7. Did a compression 215 psi and leakdown and everything checks out. If I pull the plugs they all look normal except 2 & 7. Both of these plugs have a good amount of carbon buildup. I also saved the old plugs I removed before I started this job and noticed 1 plug from each bank was more carbon'd then the rest of the plugs. I don't know weather it was 2 & 7 but I assume it was. At first I was thinking maybe I received 2 bad primary injectors but the plugs before the injectors kind of ruled that out in my mind. I was thinking maybe a bad ECM ?? Suggestions please help Last edited by J & J Speed Shop; 07-23-2013 at 02:26 PM.