Hot start misfire and CEL?
07-24-2017, 01:28 PM
#1
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Hot start misfire and CEL?
Hi folks - hoping for some suggestions here.
I've been chasing an intermittent CEL issue for a while which only appears to trigger on a hot start.
I can drive the car for months without triggering a problem IF the car cools completely between starts. But if I'm out for a drive, stop for food or fuel (or whatever) then re-start, I frequently get a CEL and a misfire code. My shop says the misfire codes don't appear to be isolated to any one cylinder or bank.
The car has new spark plugs, ignition wires, caps and rotors, fuel filter, and the distributor belt appears to be in good shape.
Anyone have any ideas about what's happening here?
I've been chasing an intermittent CEL issue for a while which only appears to trigger on a hot start.
I can drive the car for months without triggering a problem IF the car cools completely between starts. But if I'm out for a drive, stop for food or fuel (or whatever) then re-start, I frequently get a CEL and a misfire code. My shop says the misfire codes don't appear to be isolated to any one cylinder or bank.
The car has new spark plugs, ignition wires, caps and rotors, fuel filter, and the distributor belt appears to be in good shape.
Anyone have any ideas about what's happening here?
07-24-2017, 02:58 PM
#2
The typical culprits in no specific order are O2 sensors, a failing DMF, or crank position sensor failing or out of adjustment.
Since your issue is primarily during hot starts, and no specific bank or cylinder, I would tend to suspect O2 sensors.
Since your issue is primarily during hot starts, and no specific bank or cylinder, I would tend to suspect O2 sensors.
Last edited by nine9six; 07-25-2017 at 03:18 PM.
07-25-2017, 03:14 PM
#4
Yes, with a good OBD II reader that will read the O2 sensor voltages in real time.
I have an older Actron 95xx series reader and it reads the voltages just fine.
I also have the durametric diagnostic tool which will do the same.
After further thought, crank position sensor failing or out of adjustment, might also produce your hot start CEL issues.
I have an older Actron 95xx series reader and it reads the voltages just fine.
I also have the durametric diagnostic tool which will do the same.
After further thought, crank position sensor failing or out of adjustment, might also produce your hot start CEL issues.
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06-07-2018, 02:52 PM
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Just to close this off for future reference:
During my engine-out clutch/flywheel replacement (and other stuff), my shop noticed the SAI valve was completely caked and corroded. They replaced it, and now my hot-start misfires and CEL are gone! I love not worrying about this anymore!
During my engine-out clutch/flywheel replacement (and other stuff), my shop noticed the SAI valve was completely caked and corroded. They replaced it, and now my hot-start misfires and CEL are gone! I love not worrying about this anymore!
06-07-2018, 02:55 PM
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I'm not actually sure how to confirm it wasn't related to the DM flywheel too. The shop said the flywheel was quite worn, and they agreed it was ideal to replace it.
In what ways does a DMF "fail"?
In what ways does a DMF "fail"?
