#4 missfire

Scootin14 · February 17, 2019

My truck runs fine in manual mode in 5th gear. As soon as I put it in drive and it switches to v4 I get a missfire, idles like I have a massive cam and the down shift from 2nd to 1st coming to a stop will about put you through the windshield. But if I shut off the truck for 5min it all goes away as long as it's in manual mode. Checked compression, changed plugs and have swaped coil packs with no difference. Went to the dealership and I'm a week out of warranty so now I've got to figure this out. Any suggestions.

1SLOW1500 · February 17, 2019

Week out of warranty doesn't matter. If it was me read codes the check pin outs then new coil all new wires and spark plugs. Reset and test.

wacko · February 17, 2019

My injector failure sounds similar. If I hit a slight incline and gently rolled throttle at 1800-2200 rpm it would throw the misfire code. Also poor idling. Awkward downshift as well

1SLOW1500 · February 17, 2019

My injector failure sounds similar. If I hit a slight incline and gently rolled throttle at 1800-2200 rpm it would throw the misfire code. Also poor idling. Awkward downshift as well

You can see that in the fuel tables and also in the o2 upstream also in the commanded fuel.
Again with the codes and the printed history report gm will cover it. But longer you wait harder it is to address.

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