1998 k2500 engine miss

Tiny
ECUSTA
  • MEMBER
  • 1998 CHEVROLET TRUCK
I have a 1998 chevy k2500 5.7L with 94,000 miles and have developed a miss while the engine is running at low idle speeds. After the engine warms up a bit they are not as bad but still there. Also engine backfires and lags on damp or rainy days. I have replaced wires plug and rotor and dist cap all gm parts from dealer. No obd codes. Not truck is starting like battery is weak and will no crank and fire over. Load tested battery. OK. Please help :
Thursday, March 1st, 2007 AT 7:43 AM

7 Replies

Tiny
CHEVY22
  • MECHANIC
  • 1,375 POSTS
Hmm, worse on rainy days, you could try the old backyard test, get a spray bottle with some water and start on one component at a time, dist, wires and see what happens, check fo leaks at the intake and check all vacuum lines and let me know what happens

thanks, jim

oh and if you are happy with the info please leave some feedback we all donate out time here helping people for free
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Thursday, March 1st, 2007 AT 11:57 AM
Tiny
ECUSTA
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I have Tried the backyard test as a matter of fact. Only I preformed this at night to better see any type of arcing with no results :( I have run out of ideas on what to do before taking it to the dealer. I dont just want to start to replacing things if it is something simple.
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Thursday, March 1st, 2007 AT 2:30 PM
Tiny
CHEVY22
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You sound like me, I will test and retest before I replace a part,
you were saying something about the battery also? And is there anything else going on, and def no codes yet? If it was electronic it would set a code maybe were looking in the wrong place?Any smoke or loss of coolant, anything you can think of

lemme know
jim
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Thursday, March 1st, 2007 AT 2:47 PM
Tiny
ECUSTA
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I dont know how to explain the battery issue. Sometimes the engine cranks like the battery has been overworked. I then go out and verify the battery terminals are indeed tight. And truck will start up like normal but the miss is still there. :Shock: Very odd on how this is working. But battery has been load tested and teased fine. Battery terminal are also clean. :) Some one told me it could be the pickup in the distribitor and some has told me it could be the control mod. At this point I 'm baffled
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Thursday, March 1st, 2007 AT 2:56 PM
Tiny
CHEVY22
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It could be the cam or crank sensor or even the iac but right now I wont point fingers, have you hosed down the ecm? Hmm I need to pick my brain a while, I wish I was there, if you have an ohm meter we could do some testing?
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Thursday, March 1st, 2007 AT 3:04 PM
Tiny
ECUSTA
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I have a ohm meter. What do you have in mind.
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Friday, March 2nd, 2007 AT 5:35 AM
Tiny
CHEVY22
  • MECHANIC
  • 1,375 POSTS
I had to e

jimmail the data, it would show up too small here, when you have time start there, alo do you have access to a fuel pressure gauge? There were some problems with the injection units on all trucks from 94 and up
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Friday, March 2nd, 2007 AT 7:18 AM

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