LT1 ignition issues at high RPM, flashing SES light
08-31-2016, 11:20 AM
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LT1 ignition issues at high RPM, flashing SES light Hey guys, I have something with my LT1 that's got me stumped. When the car is warm, I seem to be having a bit of an ignition issue at high RPM (4500+). You can see it in the dyno traces:
In the build, I installed a brand new opti, brand new NGK TR55s gapped to .050", and new wires. After getting this result, I tried installing a brand new coil, didn't help. Then I installed a brand new ICM, and it didn't help either. Furthermore, since installing the ICM, the Service Engine Soon light keeps flashing. When I scan the module, there are no DTCs being thrown.
I'm really running out of ideas. My next thought was to do new spark plugs again. During my build I had to sort of start over because some debris damaged one of the heads and it was running coolant into the cylinders. My thinking is maybe getting coolant all over the tips could have wrecked the plug somehow. I talked to my tuner, and he recommended getting some NGK TR5s and gapping them to .040". I plan on doing that this weekend.
Any other thoughts from anyone here? My tuner and I are both stumped right now.
In the build, I installed a brand new opti, brand new NGK TR55s gapped to .050", and new wires. After getting this result, I tried installing a brand new coil, didn't help. Then I installed a brand new ICM, and it didn't help either. Furthermore, since installing the ICM, the Service Engine Soon light keeps flashing. When I scan the module, there are no DTCs being thrown.
I'm really running out of ideas. My next thought was to do new spark plugs again. During my build I had to sort of start over because some debris damaged one of the heads and it was running coolant into the cylinders. My thinking is maybe getting coolant all over the tips could have wrecked the plug somehow. I talked to my tuner, and he recommended getting some NGK TR5s and gapping them to .040". I plan on doing that this weekend.
Any other thoughts from anyone here? My tuner and I are both stumped right now.
08-31-2016, 12:16 PM
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Like I said, scanning the PCM doesn't pull anything up. The module isn't setting any trouble codes to indicate why it's flashing the SES light.
08-31-2016, 12:54 PM
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A flashing SES is indeed multiple misfires of a cylinder(s) in a given amount of time. IIRC you need to scan the PCM while the engine is running? I thought it stored misfires as well. Maybe not.
08-31-2016, 01:49 PM
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Did you data log or just scan the PCM? Sorry but I haven't messed with this kind of **** for awhile. Do you just have a scanning tool or is it able to log live data while the engine is running?
08-31-2016, 01:56 PM
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Flashing SES light is an indication of a misfire condition. It should at least trigger a P0300 random misfire code if not a P030x 'x' signifying the cyl(s) misfiring.
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08-31-2016, 02:36 PM
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That's what I figured as well. It threw that code on occasion before I took it to the tuner, so it's not like that code is disabled or anything. And it doesn't subjectively feel like it runs any differently now than it did before I swapped the ICM and before the SES started flashing.