1997 Chevy Suburban Random multiple misfire

1997 CHEVROLET SUBURBAN
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ANGELA59
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Engine Mechanical problem
1997 Chevy Suburban V8 Four Wheel Drive 175000 miles
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This misfire is worse on Cyl 3 AND 8. Have replaces all injectors, distributor, plugs wires, cap, had heads reworked, Mass air flow and ignition control module. Got 125lb of compression on 3 and 8.
Mar 4, 2008 at 12:57 PM
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MERLIN2021
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What's the compression on the others? 125 sounds a bit low, how did the cylinder walls look when you took off the heads? Is there any blue smoke when it's running?
Mar 4, 2008 at 1:05 PM
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ANGELA59
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All cyl range from 125 to 135 psi. Cyl walls looked good and there is no blue smoke
Mar 4, 2008 at 1:17 PM
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MERLIN2021
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Try using a noid light on the 3 and 8 injectors, this will test the injector harness to see if it's firing the injectors...othe than that check for vacuum leaks with some gumout spray, Does yours have the plastic manifold? And if you need more help please post the engine size in liters, it's listed on the white VECI label under the hood...
Mar 4, 2008 at 1:35 PM
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ANGELA59
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I do have current with noid light, no vacuum leaks, has got plastic planum. it is a 5.7 with spider injectors
Mar 4, 2008 at 1:41 PM
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MERLIN2021
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If you can fill me in on what you HAVE done so far, instaed of me asking and then you telling me you've done it already, I might be able to figure something out...
Mar 4, 2008 at 2:33 PM
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ANGELA59
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I put in the 1st question that I replaced the injectors, plugs, wires cap, distributor, mass air flow and ign cont module and had the heads worked. if the cyl walls had not looked okay I would have stopped before i worked the heads. I realize that I may have left out something. That's why I am asking for help. I tryed to remember every thing at once so someone would be well informed. Sorry!
Mar 4, 2008 at 2:59 PM
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MERLIN2021
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I will send some info so You can read it...
Mar 4, 2008 at 3:26 PM
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ANGELA59
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Thanks a million. Will read over and do some testing and get back with results tommorrow.
Mar 4, 2008 at 4:13 PM
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ANGELA59
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Figured out what the problem was. A Crank Sensor. Thanks so much for your help. had to just get away from it for a little while and let the frustration die down, now the car runs great.

Angela
Mar 7, 2008 at 2:03 PM