AL Posted September 18, 2010 Report Share Posted September 18, 2010 So my friends 98 GP was purchased with a misfire... Right away we bought a new battery... It has new headgaskets and new plugs and wires but the wires all broke inside the boot... So the wires from Breakdowns car live on... But I started the diagnosis with the scantool and I found a bad MAP and bad ECT... I replaced both... Misfire still there... I then ohm checked the coils and fuel injectors, all coils were 6.04 and all injectors were 12.4... So today I pulled the fuel rail and put paper towles under the injectors and checked flow... All the puddles were the same size... I then replaced each coil... no change... I am having her test the ICM tomorrow and am waiting on the result... What do I check for next? Quote Link to comment Share on other sites More sharing options...
Addicted to eaton Posted September 18, 2010 Report Share Posted September 18, 2010 cracked plug? bad plug?. Could still be a Coil.... Gap on spark plugs? compression test. Quote Link to comment Share on other sites More sharing options...
AL Posted September 18, 2010 Author Report Share Posted September 18, 2010 I pulled all the plugs, they look brand new... I replaced the coils .060 Not yet Quote Link to comment Share on other sites More sharing options...
birdman Posted September 18, 2010 Report Share Posted September 18, 2010 Is it a dead miss (one cyl never fires)? If so pull one plug wire at a time and see which one didn't make a difference. That will at least tell you which cyl is causing you problems. Quote Link to comment Share on other sites More sharing options...
AL Posted September 18, 2010 Author Report Share Posted September 18, 2010 It feels like maybe a dead miss... It shakes the car but not very bad... Its weird... Ill do the plug wire trick but everything on each cylinder has been replaced or has be checked good Quote Link to comment Share on other sites More sharing options...
wickedbuick Posted September 18, 2010 Report Share Posted September 18, 2010 It feels like maybe a dead miss... It shakes the car but not very bad... Its weird... Ill do the plug wire trick but everything on each cylinder has been replaced or has be checked good also try unplugging one injector at a time to see if that changes anything Quote Link to comment Share on other sites More sharing options...
ruktosk Posted September 18, 2010 Report Share Posted September 18, 2010 Vacuum leak? Maybe, maybe not? Just throwing out ideas... Are any of the plug wires grounding to the chassis anywhere? Quote Link to comment Share on other sites More sharing options...
wickedbuick Posted September 18, 2010 Report Share Posted September 18, 2010 Vacuum leak? Maybe, maybe not? Just throwing out ideas... Are any of the plug wires grounding to the chassis anywhere? I have had the ICM fail on me giving similar results. On a different occasion, I have also had NEW plugs with about 2000mi on them and they looked great and gap was still where I needed it but the car had a crazy miss. I replaced everything including the ICM(used) and still missing. Replaced the plugs and it ran SMOOTH..... so with plugs being cheap I'd try that anyway. I just use Autolite104s (with the mods I have) with great results and ACDelco as well. Hopefully one of the several suggestions in the thread fix it Quote Link to comment Share on other sites More sharing options...
wickedbuick Posted September 18, 2010 Report Share Posted September 18, 2010 It could be choking from all the "sucking" that motor is doing cause my car "blows" all day long and she never chokes, spits, or spudders Quote Link to comment Share on other sites More sharing options...
AL Posted September 18, 2010 Author Report Share Posted September 18, 2010 That was cheesy... Ill check the plugs again today Quote Link to comment Share on other sites More sharing options...
wickedbuick Posted September 19, 2010 Report Share Posted September 19, 2010 That was cheesy... Ill check the plugs again today haha i know So any luck? Quote Link to comment Share on other sites More sharing options...
AL Posted September 19, 2010 Author Report Share Posted September 19, 2010 Didn't touch it Quote Link to comment Share on other sites More sharing options...
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