UT4Vida
02-25-2025, 18:35
1997 Tahoe 164k new stock turbo, new bosch injectors, vacuum waste gate, EGR, No Check engine light, no codes, Leroy PMD relocation in the bumper.
I bought my truck last summer and drove it in from Austin to Houston. It ran fine, some black smoke when I punched it.
Parked it and started working on little things it needed--new batteries, new alternator, new belt, new air filter, new cross over pipe, changed oil and fuel filter and relocated the PMD. I would drive it at least once a week. About a month later I started noticing thick black smoke and some injector knock. It got progressively worse. It got to the point that I couldn't get it over 20mph without huge plumes of black smoke and loud injector knock. If I'm cruising or at idle, no smoke or knock. It starts right up and there are no codes.
I assumed my smoke was from over fueling/low air flow. I replaced the turbo, injectors, fuel sending unit and installed a raptor fuel pump with a pre-pump filter, replaced the FFM (it was leaking). Still the same.
I took out the glovebox to eyeball the PCM--no stickers or other signs from the outside that it's been tuned. Vacuum pump closes waste gate shut at idle. I measure at least 20 inches at the waste gate and at the solenoids.
Here's a pic of my scanner at idle. Does the boost sensor take atmospheric pressure into account? If yes then 14 psi is normal if not then 14 psi at idle is outrageous. Could this pressure reading cause the IP to dump more fuel? I have a baro sensor on my firewall. I've got to be overlooking something but I can't figure it out. Any ideas?
7881
I bought my truck last summer and drove it in from Austin to Houston. It ran fine, some black smoke when I punched it.
Parked it and started working on little things it needed--new batteries, new alternator, new belt, new air filter, new cross over pipe, changed oil and fuel filter and relocated the PMD. I would drive it at least once a week. About a month later I started noticing thick black smoke and some injector knock. It got progressively worse. It got to the point that I couldn't get it over 20mph without huge plumes of black smoke and loud injector knock. If I'm cruising or at idle, no smoke or knock. It starts right up and there are no codes.
I assumed my smoke was from over fueling/low air flow. I replaced the turbo, injectors, fuel sending unit and installed a raptor fuel pump with a pre-pump filter, replaced the FFM (it was leaking). Still the same.
I took out the glovebox to eyeball the PCM--no stickers or other signs from the outside that it's been tuned. Vacuum pump closes waste gate shut at idle. I measure at least 20 inches at the waste gate and at the solenoids.
Here's a pic of my scanner at idle. Does the boost sensor take atmospheric pressure into account? If yes then 14 psi is normal if not then 14 psi at idle is outrageous. Could this pressure reading cause the IP to dump more fuel? I have a baro sensor on my firewall. I've got to be overlooking something but I can't figure it out. Any ideas?
7881