98 Suburban misfire
January 23rd, 2012, 9:32 PM
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98 Suburban misfire
Hello to all and thanks in advance for your help!
I own a 1998 Suburban with a 5.7 engine. I have replaced cap, rotor, wires, plugs and mass airflow sensor. Intake manifold gasket was replaced approx. 2 years ago. Vehicle misfires when cold under light acceleration and at idle. When it's damp outside, it is worse. Now vehicle will not start. Fuel pressure is 65 lbs, no other repairs have been made to engine. Vehicle has 133,000 miles. I checked for codes (didn't see a MIL light but guess the bulb is burned out) and vehicle has three active codes: P1345, P0141, and P0153.
I own a 1998 Suburban with a 5.7 engine. I have replaced cap, rotor, wires, plugs and mass airflow sensor. Intake manifold gasket was replaced approx. 2 years ago. Vehicle misfires when cold under light acceleration and at idle. When it's damp outside, it is worse. Now vehicle will not start. Fuel pressure is 65 lbs, no other repairs have been made to engine. Vehicle has 133,000 miles. I checked for codes (didn't see a MIL light but guess the bulb is burned out) and vehicle has three active codes: P1345, P0141, and P0153.
January 23rd, 2012, 10:08 PM
#3
P0141 and P0153 won't prevent the engine from starting but P1345 will. Chances are, the distributor gear is worn to the point that the CMP sensor is way out of alignment. MDTAHOE himself explained the issue pretty clearly in thread https://chevroletforum.com/forum/gen...72/#post202040.
January 23rd, 2012, 10:12 PM
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I have to charge the battery first.... Don't know why I didn't check that first! Thanks. Also, I replaced the plugs with autolite plugs. I know in newer vehicles (Chryslers come to mind) that if you use other plugs it will sometimes cause problems. I think that the distributor was not installed correctly after the intake manifold gasket was replaced. I've noticed that I have a slow start condition when the engine is warm. Will that cause the misfire/no start? I didn't know about MIL because I had never had a need to put a scan tool on it until now.
Last edited by burb-guy; January 23rd, 2012 at 10:24 PM. Reason: Forgot to add something
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January 24th, 2012, 7:55 PM
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I found the dis. hold down was loose (thanks to the crack shop that did the intake gasket) so the dis. is our of adjustment. I can't think of anything else it could be given all that's been done. I can borrow a scan tool. I saw in MDTAHOE's post the timing needs to be at 0 degrees +- 2 degrees. When I can get it running, I'm guessing I look at live data and see that the timing is at 0 degrees? Is there anything I need to unhook before checking that?
January 24th, 2012, 7:58 PM
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Nothing to disconnect. After each adjustment you must snap the throttle to update reading. In snap on scan tool it is listed as knock retard. In the trouble shooter it has a distributor adjustment procedure which automatically brings up "knock retard".
