Multiple Cylinder Misfire
August 27th, 2009, 11:50 AM
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Multiple Cylinder Misfire
Hey guys, I'm not one to join in on a forum just to get some advice but I don't have any other choice now, unless I get a tow to the stealership. I've got an 03 Express 3500 6.0 van. I didn't see a section for the express's so I figured silverado's are close enough. Well I'm getting the mult cylinder misfire code. Plugs and wires have been changed to AC Delco stuff. New fuel filter and air filter. I'm still getting the code after that. I ohm'd out the knock sensors and they both ohm'd 100k which was right. I also ohm'd 6 of the 8 coil packs out and they all were identical. I ohmed them by reading across the 2 center pins, I couldn't reach the front two easily so I left it at that. Do you guys have any suggestions where I should go from here? The truck ran beautiful then suddenly it wouldnt accelerate much more than 20-30mph. Even at idle now it's running pretty shakey. I would appreciate absolutely any advice, since I'm grabbing at straws here. Thanks!
August 27th, 2009, 12:41 PM
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Multiple Cylinder Misfire
How about the crank position sensor (CPS)? The ring is usually attached to the harmonic balancer, make sure that it is still "round", and that there are no bends in the metal ring. Also disconnect and reconnect the CPS electrical plug.
Success,
Success,
August 27th, 2009, 1:18 PM
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August 27th, 2009, 1:44 PM
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Lol I'd replace it if I could...I'll look into that crank postion sensor though. I've in the middle of pulling the intake manifold off. It would be so much easier if this thing was in a truck chassis. Thanks
August 27th, 2009, 3:01 PM
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bad info from the O2 sensors could be telling the computer to adj the fuel causing a mis-fire too much too little? guess that would probably cause a lean issue...
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August 28th, 2009, 12:04 AM
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Try taking a vacuum reading just after startup, then keep monitoring the reading until the engine warms up, if the reading starts to drop it is possible that the exhaust is stopped up. Also listen at the tail pipe for a whistling sound when the engine is excellerated, also indicating a stopped exhaust.
August 28th, 2009, 4:37 PM
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I'll do that next once I get the intake and what not back together. Thanks for the suggestion, I wouldn't think it would be exhaust related since it was so sudden that it started acting up but it's worth looking into.
