January 27, 2024 at 6:10 pm #798195
I have a 2007 silverado with the 6.0 vortec max.
Been running into issues the last few weeks.
Starts and runs fine when cold but after it gets warmed up runs poorly and wants to die unless i keep my foot on the gas.
No check engine light ever, no codes, no nothing. Its leaving me clueless as to what it could be.
I have already replaced some things i thought it could have been but still having the same issue.
Replaced so far-
Throttle body, MAP sensor, MAF sensor, New battery, plugs and wires
Sometimes when i’m driving along it seems fine then all a sudden it seem like it almost goes into limp mode and gets gutless unless i step on the gas then it seems to come out of it but at normal driving speed it will decelerate until i give it more gas. It will idle poorly after it does this until i stop and put in park. It will sit and idle in park all day long with no issues, its until i put it in gear and get going it starts running poorly.
We did a fuel pressure test the other day and that seemed to be fine.
I’m at a loss with this as its not giving me codes or anything to go by.
Someone please help me out here.
January 29, 2024 at 7:37 am #798243
Have you checked fuel pressure while driving (under load)? Usually if it runs bad when hot, that’s a fuel pump/regulator issue. If you’re able to read fuel trims you could see if it runs rich (coil or injector issue) or lean (fuel pump or injector issue). First i would bench test each coil if you have a multimeter (free), next hold a stethoscope (long piece of metal or screwdriver) against your ear on each injector while its running to make sure each one has a consistent clicking, if that checks out then replace the fuel filter and if that doesn’t work then its most likely fuel pump.
January 29, 2024 at 7:43 am #798247
Also if you have an infrared thermometer, you can shoot each header tube to see the temps. If one is drastically different than the other than that would identify the problem cylinder (coil or injector), if not then again it’s probably the fuel pump
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