Tahoe Misfires after Heavy Accleration

[1BADI5]

I was going to do some shorty headers too, but i will wait til spring for that. I'm more focused on reliability, passing emissions and getting the MPGs up.

The last tank was 9.1 mpg......but thats with a bad spider and a minor intake gasket leak. I would like to see 17 mpg......20 would be ideal. My 08 Tahoe LTZ can get 20-22mpg

 

[drakon543]

My 97 atm gets 17 mpg avg from my house to work and back. A good chunk of it is highway tho. Shortys wont get you the best power gain and the pacesetters i had didnt change the sound much. But they will get you a boost in mpg. Ive never tested it myself as i have no intention on buying 2 sets of headers but the claim on shorties is better mpg gain vs long tubes. So ive just stuck with that information and only run shorties. Had an 94 f150 extended cab 4x4 with the 302 avg 19 mpg until the torque converter went bad. I was running a cai, accel performance plugs and wires (just for the more stable spark), shorty headers dual exhaust with an h pipe on that with flowmaster 40s.

 

[1BADI5]

@drakon543

This 99 is going to be my winter beast / bad weather daily. I'm also realistic, its almost 20 years old and has 200k on it. I'd settle for 15 mpg, but I live in the mindset more is better.

I want to build it solid....because in the next year or 2 its going to be my tow pig when I LS/T56 swap my 04 Colorado

 

[McClane]

Replaced the distributor on Friday. It had a lot of slop in it and the gear was worn. Unfortunately it didn't solve my problem. It's still misfiring when you let off the gas after heavy acceleration. Any other ideas?

 

[DallasTahoe]

Have you put it on a scanner to see where you have the misfires?


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[1BADI5]

Yes, PO303.

 

[DallasTahoe]

Ok so cylinder 3 is your issue, swap wires, change plugs, and compression test done yet? If yes then next thing it to pull the valve cover and reset the valve lash


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[McClane]

Mine is not throwing any codes right now since fixing the p1345 code from the distributor.

 

[McClane]

Pulled my boat this past weekend. Any time I went up a hill it would start missing after about 5-10 seconds on the hill. Could it be the coil is weak?

 

[99Vortec]

Yea. Mine is at above 220K and same thing. Misfiring on HEAVY acceleration. (Like4 going uphill.) (P0307) In my case.