P0300 error after new plugs and wires

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OR VietVet

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If he/she has the right scanner, he can drive it and watch and see what is going on when it actually happens.
 
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J

jonp365

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Well, I got to pay the "stupid tax", but it was only $105 for diagnostics, so it could be worse. Misfire was coming from #8 cylinder. When I was double checking the 2, 4, 6, and 8 wires, I didn't remove the wheel and liner to get good access, I simply reached in. Apparently I did not fully seat the wire and my double check was not good enough to notice it. I should have taken the time to do the check properly. It explains why driving around the neighborhood and anything lower than 50mph/4k rpms didn't reproduce the issue. It only happened when I really got on the accelerator...when #8 would have been required. So they fixed my poor seating job and its all good. First time I've done spark plugs on a Tahoe, so learning experience. Mental note for next time...in another 100k miles. Maybe this will help someone. Thanks to all who helped and gave me advice!
 

OR VietVet

Multnomah Falls
Supporting Member
Military
Joined
Oct 8, 2014
Posts
20,508
Reaction score
35,882
Location
Willamette Valley
Well, I got to pay the "stupid tax", but it was only $105 for diagnostics, so it could be worse. Misfire was coming from #8 cylinder. When I was double checking the 2, 4, 6, and 8 wires, I didn't remove the wheel and liner to get good access, I simply reached in. Apparently I did not fully seat the wire and my double check was not good enough to notice it. I should have taken the time to do the check properly. It explains why driving around the neighborhood and anything lower than 50mph/4k rpms didn't reproduce the issue. It only happened when I really got on the accelerator...when #8 would have been required. So they fixed my poor seating job and its all good. First time I've done spark plugs on a Tahoe, so learning experience. Mental note for next time...in another 100k miles. Maybe this will help someone. Thanks to all who helped and gave me advice!
Just today I replaced the valve cover gasket on a 1986 Nissan pickup 2.4. Has 2 plugs per cylinder. I checked the plug wires that he paid someone, about a year ago, to replace with the 8 plugs. The back d/s wire was not seated on the plug tip. I could wiggle the plug boot like the plug tip was broke. I drove it before working on it, I always do. Had a slight ruff idle and misfire and he said it was driving fine. I pulled the plug wire boot and all looked good. I plugged back on and felt the click. Smoothed out the idle and now no misfire. Alaways double and triple check your recent work.
 

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