2002 cmc with multiple misfire codes

Tiny
JDRUID
  • MEMBER
  • 2002 GMC SAVANA
  • 150 MILES
I have a 2002 GMC savana with a brand new gmc crate motor with less than 150 miles. It is throwing a multiple misfire code on cylinders 4&7. It was giving the same exact code before we replaced the engine. We have replaced the mass air flow, crank and all the o2 sensors. We were told we may need to reflash the computer we have taken to our local gmc garage and they said they could not find anything any suggestions
Tuesday, September 13th, 2011 AT 2:55 PM

5 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
What about the injectors? Very important as the flow pattern may be off either giving too much or too little fuel in the cylinders.

Roy
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Tuesday, September 13th, 2011 AT 5:46 PM
Tiny
JDRUID
  • MEMBER
  • 3 POSTS
Yes we have checked all the injectors and they are all fine. Distributor is fine, they spent 4 hours checking everything they could and still getting the same codes. It does not throw the codes when under load but as soon as we let off the gas the service engine light comes on with the multiple misfire codes
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Wednesday, September 14th, 2011 AT 12:39 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Are there any exhaust leaks?

Roy
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Wednesday, September 14th, 2011 AT 12:59 AM
Tiny
JDRUID
  • MEMBER
  • 3 POSTS
No there are no exhaust leaks.
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Wednesday, September 14th, 2011 AT 11:20 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Sounds like you have covered all the bases with the same results. You need help of a shop with a scanner to monitor whats happening with this system. It may be a bad pcm but needs to be confirmed before this expense.

Roy
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Wednesday, September 14th, 2011 AT 2:18 PM

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