Same thing happened to me after doing cap/rotor/wires/plugs at 193k. Turns out #1 has no compression and #4 is misfiring. Haven't had any more time to check the wires or timing or why there is no compression in #1.
HELP 00 K2500 CCSB 5.7 is A GUTLESS gas guzzler
- Thread starter TGS00
- Start date
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tomb
OBS Enthusiast
If compression tests good, you still have tons of things to check with that mileage an symptom Id have to replace the O2 sensor first then check torque converter operation, I use the high end Harbor Freight scanner. Verify coolant temp matches reality. Compare readings to another 5.7. (On a separate note, could fuel pressure be too high? Not regulating correctly)
dowsewashere
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Damn good looking truck for 271k
Thanks!
She takes a good picture but has more than her fair share of dents, dings a scratches. Most people don't believe it has that kind if mileage though.
schwarze_crewcab
OBS Enthusiast
The best ice gotten with mine is 14. Admittedly the 5.7 is a bit inadequate for a pickup of this size. I have also noticed the type of fuel I use makes a difference. I get substantial better mileage by running 91 octane ethanol free gas. This spring I am going to get a black bear tune calibrated for 91 and see what that does for me.
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What is your truck running for gears? I was talking to a lot shops around here and most of them said to get rid of the 3.73s and put 4.10s. They figured it's be better mileage and more power. I'm going to have the fuel pressure test ASAP as well as compression
schwarze_crewcab
OBS Enthusiast
3.73s
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tomb
OBS Enthusiast
Guess it depends on how you use the truck. When I had stock wheels anything over 70 mph felt like the engine was racing. I now run 315/70R17s tires which helped on the top end. I think 75mph = 2000 rpm. (3.73)
When I swapped tires I sent my PCM to for a black-bear tune that accounted for my tire size.
I dont really want to burn rubber but it will still spin the G80 with new BFG's.
I wish I knew my MPG... have not checked it since tune.
When I swapped tires I sent my PCM to for a black-bear tune that accounted for my tire size.
I dont really want to burn rubber but it will still spin the G80 with new BFG's.
I wish I knew my MPG... have not checked it since tune.
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tomb
OBS Enthusiast
Wow, just checked MPG =13 and she is running perfectly so I assume its as good as it gets.
schwarze_crewcab
OBS Enthusiast
Probably can't ask for better than that.
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