How to use EFIlive to debug a flashing 'service engine soon' light.
I am trying to diagnose a flashing SES light which i get while cruising at about 2600 RPM's on the freeway. Can anyone recommend the best way to do this? From what I have read it has something to do with a misfire (but I am not getting any stored codes). How do I monitor for this condition? Is there a cylinder misfire count I can watch for? Unburnt fuel number?
Flashing SES = misfires detected
With your EFILive scantool, connect and click the OBD tab, and see what DTC's are read.
Some PCM's support a per cylinder misfire count, on the PIDs tab look for the pids MFCYL1C, MFCYL2C, ...
Flashing check engine light will be a random misfire. I've found it best to diagnose misfires the old fashioned way, the misfire counts can't be exactly trusted. I would check your intake gaskets, fpr, maf/map, etc...Originally Posted by bubba68ss
03 Silverado 5.3 ECSB 4x4 Z71
Comp Cam 206/212 .515/.522 112 lSA, hardened rods with LS9 springs
2010 Tahoe VVT AFM 5.3
Stock for now
Gregs has a good point.
If you can't find the cause, you'll have to also do compression/leak down tests, check your coolant level.
I have about 4k miles on this engine. i did the swap in August, I'm hoping gaskets are holding up... It's weird, I am not getting any p0300's or anything... I do not feel any misfires either. I even looked at the LTFT's on my scangauge II (I have mounted to my dash) while the SES was flashing and and they were within specs.
Besides a cylinder not getting spark or fuel, what else could cause a misfire? You mentioned a compression test? The only thing I have noticed that is odd is my oil was getting real dirty real quick but I did have a bad leak and it was also a fresh rebuild... As for wiring, I added two additional injector wires but I soldered and heat shrinked them.
So this isnt in a stock vehicle? Do you have headers?
~Erik~
2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.
It's a 99 s10 with 0411 PCM and a 5.7 with a 2002 Chevy express tune.
oil getting dirty quick = compression/blowby leak
Exhaust gas getting past the rings? Damn. Engine has new rings, valve seals, everything.
Just did a dry compression test and the cylinders ranged from 165-180. Can I rule out any 'blow-by' or leaky valves? Does that rule out the engine internals?
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