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Steve B
New User
Apr 7, 2010, 6:00 AM
Post #1 of 4
(3591 views)
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97 suburban runs rough
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This problem child is a 1997 Chevy Suburban with a 5.7L with 127K miles on it. This thing showed up with a hard miss at all rpm ranges, poor power, and terrible fuel mileage. Customer complaint: "It shakes the dash and won't hardly pull out of the garage." What I have done to this point: Complete tune up incl. plugs (AC) plug wires, dist cap & rotor, fuel filter. Checked for codes, found one (timing correlation code). Checked and replaced both crankshaft and cam position sensors. Checked timing at dampener, found timing waaaay off. Static timed engine and checked dist timing and found dist off 2 teeth and dist gear worn bad. Replaced gear and retimed dist. At start up after all this no change in engine. Performed a complete compression test and leak down test. compression at 120psi-140psi. leak down showed minimal leak and no leak between cylinders. pulled torque converter loose from flywheel, restarted and no change. put it all back together and got on line looking for help
Thanks in advance for any help. I will post the fix.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 7, 2010, 6:26 AM
Post #2 of 4
(3589 views)
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Re: 97 suburban runs rough
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This is the "R" code engine right? They are crazy to have exact fuel pressure! Off top of head - 60-66 psi. Anything less problems begin and won't run much below 58psi! Must rule that out. You've done a lot of stuff that shouldn't have been off like timing issues unless you think chain is trashed??
T
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Loren Champlain Sr
Veteran
/ Moderator
Apr 7, 2010, 7:48 PM
Post #3 of 4
(3583 views)
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Re: 97 suburban runs rough
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Steve; Once you've checked fuel pressures, as Tom suggested and would've been my first test, give us vacuum readings at idle and cruise. The PCM 'takes care of the timing', so that has me concerned, as well. I'd have to check, but some of the GM V8s require a synchronization procedure.
Loren
SW Washington
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Hammer Time
Ultimate Carjunky
/ Moderator
Apr 8, 2010, 2:47 AM
Post #4 of 4
(3582 views)
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Re: 97 suburban runs rough
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The timing is not adjustable on this engine. I assume you are getting a P1343 which means the distributor has been moved annd is not synched any more. You will need a professional scan tool to set the distributor offset to 0. If it's off more than 4 degrees, it will set the code and run terrible.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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