Tahoe dies out while driving not all the time. What's going on???

[JustClean86]

I've already replaced (in order as the problems occured) my fuel pump, fuel filter, heater core, all air filters(cabin and in engine), spark plugs and plug wires. But still idles funny and has been losing power completely 0 rpms on highway and side streets. Not all the time but a few times in a row. I'll be at a light and when it's my green I'll get ready to go and it will die as soon as I push the gas to go. Tow haul came on once while I was parked and shut off the truck not sure why it would do that never seen it before.

 

[Kenney]

I am no mechanic but i would check the TPS MAF IAC sensors im pretty sure a mechanic can check those sensors on OBD reader. And then go from there cause it can also be fuel injectors. The list can go on but i think that should be your cheapest route for now.

 

[OR VietVet]

Sure would help to have some details. Year? Engine?

 

[swathdiver]

I've already replaced (in order as the problems occured) my fuel pump, fuel filter, heater core, all air filters(cabin and in engine), spark plugs and plug wires. But still idles funny and has been losing power completely 0 rpms on highway and side streets. Not all the time but a few times in a row. I'll be at a light and when it's my green I'll get ready to go and it will die as soon as I push the gas to go. Tow haul came on once while I was parked and shut off the truck not sure why it would do that never seen it before.

What are you driving? Stalling like this generically is usually a MAP or MAF sensor, throttle body issue or a fuel pump issue.

Do you have a mechanical fuel pressure gauge and a way to see engine parameters?

 

[steiny93]

What codes are being thrown?
What does the live data stream show? Fuel pressure at the rail?
After a stall, what is the restart like? Long crank, or fire right up?

It's one of these (spark/fuel/air)

 

[OR VietVet]

Quality of parts installed during the previous work process?

 

[Fless]

After a stall, what is the restart like? Long crank, or fire right up?

It's one of these (spark/fuel/air)

This would be good to know. Could be something as simple as an intermittent open evap purge valve dropping the vacuum.

 

[MassHoe04]

I had an issue with side post to top post battery adapter clamps. I stripped the threads once and stuck a couple of toothpicks in the threaded hole to give it some bite (and old woodworking trick with stripped screws). It held pretty good, so I kind of forgot about them for a while longer than I should have.
Then the truck was no-crank/no-start. Got tight to get home. Between there and home, then again between home and NAPA the next day... It started but ran like crap and sputtered, no power, felt like it was going to die. Got my new clamps and it was back to normal.

I just mention this only because the bad connections between the battery terminals and cable connections was good enough to let it start, but was really messing with voltages to sensors and the computer. A lot!
I am sure the MAF and MAP were just two of the things that were going wonky because voltage was all over the place.

Thought I just relay what I experienced, just in case issue could possibly be a voltage issue with battery or alternator cables/wires/connections messing with voltage somewhere...

 

[nonickatall]

It can be anything from an air mass sensor, to oxygen sensors, fuel pressure regulator, faulty air, mass problems, electrical issues.

First check for codes then proceed in sequence.

 

[bolosmith59]

I've already replaced (in order as the problems occured) my fuel pump, fuel filter, heater core, all air filters(cabin and in engine), spark plugs and plug wires. But still idles funny and has been losing power completely 0 rpms on highway and side streets. Not all the time but a few times in a row. I'll be at a light and when it's my green I'll get ready to go and it will die as soon as I push the gas to go. Tow haul came on once while I was parked and shut off the truck not sure why it would do that never seen it before.

Throttle body...

 

[SnowDrifter]

Brain dumping:

If I name off a part you've already replaced, I read your post. But.... You've replaced a lot of things and it's still being funny. And I don't quite hold a high degree of trust in new parts any more. Always verify.

- Fuel pump or fuel pump controller, depending on your year (separate module by the spare tire IIRC). Hook up a gauge, run it up by your wipers, and watch it. Should be >50psi at all times
- MAF, especially if you use an oil-wetted filter
- Missing MAF screen can sometimes make it fussy, though stalling is an unusual behavior
- Grounds / electrical connections. There are some grounds on the frame roughly under the driver's seat. Used for a lot of the car's computers. Also a common spot for things to get sad
- Again, depending on year, mix of bad alternator + bad battery could cause issue. Bad battery that has high resistance + a failing alt going full-field could be sending ~18v to the vehicle and tripping electrical bits into safe mode. I think 05+ has PCM controlled, so that wouldn't be a failure mode for those years
- Battery terminals on snug. Especially if you have e-fans.
- TPS / correlation. Both pedal and throttle side
- Again, depending on year, idle control valve (present if you have a cable-throttle on <2004 I think?)
- Vacuum leaks (look at fuel trims. >+/-10% is issue)
- Oxygen sensors (voltage should be bouncing between ~0.2 and ~0.8v. Staying at low or high needs to be looked into)
- Failing crank shaft / cam shaft position sensor (neeeeeed live data from scanner. This tells the engine when to trigger spark)