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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15201
Experience:  GM Grand Master Technician 2007. 14 years experience.
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1998 GMC k 1500 5.7L misfire on no 7 when idling its worse

Customer Question

1998 GMC k 1500 5.7L misfire on no 7 when idling its worse till warm up but still there
JA: How many miles are on the car? Is it a steady misfire? Or random?
Customer: Some what steady just replaced the injectors no change 160,000
JA: Are you fixing your 2500 yourself? What have you tried so far?
Customer: Yes need to pass emissions also new coil
JA: Anything else you want the mechanic to know before I connect you?
Customer: With code reader it completely disappears while driving that's all I have
Submitted: 2 months ago.
Category: Chevy
Expert:  Chad Farhat replied 2 months ago.

Hey how are you

1- did you scan it and retrieve fault code and got DTC P0307 only or you have P0300 and P0307 or P0207

2- The fact that it get a little better after warm up, we might have a leaking intake gasket ,if you spray starting fluid around the intake does th engine rpm surges up ,do it on cold engine so u want cause any fire

3- fuel injector flow , wring ,pcm ,any compression test done on #7 and compared to others

4- did you do a wiring harness wiggle test , does the engine misfire changes if u wiggle the harness at fuel injector 7

5- what have you done so far

Please let me know

Thank You

Chad Farhat

ASE Certified Technician