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I've got a miss and it isn't the coils


gp90se

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93 LQ1

 

Car will sometimes drive mint and sometimes feel its down a coil. I swapped out the ICM and coils for a set of known good ones, and same problem. If I restart the car, it runs fine for between a minute and 20 minutes. the wires have about 6k on them (4 years old) and the plugs are 6k miles old but installed a few months ago. I have the PCV valve disconnected and run down the other vacuum lines, everything seems to be connected okey.

 

When the miss is bad, it can and has killed the car at idle in gear, but starts right back up. higher RPM the miss can't be felt.

 

Thoughts?

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Crank sensor and/or wiring. Sounds like when I mistakenly ran the crank sensor wiring across the exhaust manifolds.

 

I was under the impression if I messed that wiring up (which I very well could have) the car would have no start issues as well

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Crank sensor and/or wiring. Sounds like when I mistakenly ran the crank sensor wiring across the exhaust manifolds.

 

I was under the impression if I messed that wiring up (which I very well could have) the car would have no start issues as well

 

My crank wires were running across the exhaust manifolds so the insulation melted, which resulted in an intermittent short. It did sometimes result in a no-start, but more often than not, it'd stall, and start right back up and go through the whole process again.

 

Check those wires.

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Could be ECM, injectors, or partially shorted injector overheating the ECM.

I would do an injector resistance test. Easiest way is to check resistance of each bank (check wiring diagram), they should be close to each other. If one bank is noticeably different, that's a good indicator it's time to pull the plenum and test the injectors individually. If I recall correctly, last time I did this I pulled a connector off of the ECM and measured resistance of each bank that way.

 

 

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Could be ECM, injectors, or partially shorted injector overheating the ECM.

I would do an injector resistance test. Easiest way is to check resistance of each bank (check wiring diagram), they should be close to each other. If one bank is noticeably different, that's a good indicator it's time to pull the plenum and test the injectors individually. If I recall correctly, last time I did this I pulled a connector off of the ECM and measured resistance of each bank that way.

 

 

x2 the front injectors are easy to check in car.... and you could measure them exactly as Gnat describes above, once you figure out which wires they are.

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i had this same problem and went through everything that was said in this thread its a dead plug this is to the op. take the plugs out one by one and see if there clean or not but if there gas soaked then there dead..

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