Truck labored acceleration and feels like its towing a load.

vududoc · May 3, 2022

I have been chasing a gremlin for quite some time and wondered if anyone had a similar issue.
The truck with one occupant feels like it is towing a load on acceleration and upon letting off the gas rapidly decelerates as if the brakes are on. Also has the 2-1 shift bump.
No current codes present and serviced the transmission no improvement. Right manifold stud repair just completed and the techs out here cant figure it out.
Just picked up alfaobd and trying to figure it all out and see more of what the truck is doing.
Any insight would be great.

P.S. on one random occasion the truck just magically fixed itself but then reverted back to constipated mode.

shortbox 8hp70 3.92 lsd 4x4 32gal tank

crash68 · May 3, 2022

Jack the truck off the ground and check the brakes, wheel bearings, etc. Also check the differential and transfer case.

indept · May 4, 2022

Check that the parking brake is not on. Make sure the cable going to the parking brake has slack in it. After driving check for overheated brake rotors by squirting water on them.

huntergreen · May 4, 2022

Was it in limp mode ?

Jeepwalker · May 5, 2022

Yeah, check for brakes dragging like they said. You should just be able to feel the rim and feel 'heat' if it is hot. Could be a bad spark plug or coil that somehow didn't set a code. Could be the MAF is dirty (do you have a cold air kit??). Fuel inector plugged?? You should be able to check those with ALFAobd.

Is there any chance your truck could have taken on some water at a previous gas fill-up?

vududoc · May 5, 2022

huntergreen said:
Was it in limp mode ?

No

vududoc · May 5, 2022

Jeepwalker said:
Yeah, check for brakes dragging like they said. You should just be able to feel the rim and feel 'heat' if it is hot. Could be a bad spark plug or coil that somehow didn't set a code. Could be the MAF is dirty (do you have a cold air kit??). Fuel inector plugged?? You should be able to check those with ALFAobd.

Is there any chance your truck could have taken on some water at a previous gas fill-up?

No water afr looks good on scan. Just reset adaptives and quick learn for transmission

vududoc · May 5, 2022

crash68 said:
Jack the truck off the ground and check the brakes, wheel bearings, etc. Also check the differential and transfer case.

Dealer checked out ok for diff but replaced front driveshaft and rf wheel bearing and r exhaust manifold. Still a head scratcher. Noted scan of trans fyr

Daw14 · May 5, 2022

Find a different mechanic .

Matt ott · May 9, 2022

Check for exhaust restriction, if it is the your engine will not develope power..

BMAC57 · May 9, 2022

Sounds like restricted exuast

mikem381 · May 9, 2022

I normally use non-ethanol fuel but with the price, I decided to try the 15 and 10 percent ethanol and that is how my acceleration felt. I switched back to non-ethanol fuel and it straightened out right away. Search for GM preferred gas/fuel you will find a list of gas stations that sell non-ethanol fuel, Conoco has a vid that runs on its pumps because ethanol in any percent is not such a wonderful thing. Never know it could be something as simple as fuel.

Elkman · May 9, 2022

A failing Crank Position Sensor will generate the problems described and it is seldom considered until it fails completely and the engine will no longer start. Prior to the CPS with engines the timing only changed when a chain or belt failed. All one needed to do was verify a spark from the plug leads to the plug tips and if that was OK then one looked at other components, usually fuel related.

A nearly plugged gas fuel filter can also cause these symptoms by restricting the total flow per minute of fuel to the engine. A change interval of 50K may be recommended but it actully depends on the amount of fuel filtered. Someone making lots of trips in town will have more fuel per mile driven than someone driving mostly on the freeway at normal speeds. Diesel engines will have monitors to know how much fuel has been consumed and this is a better indicator than the miles on the odometer for deciding when to change the fuel filter.

Dusty · May 10, 2022

With the vehicle in neutral, foot off the brakes and on a significant incline, will it roll?

Regards,
Dusty
2019 Ram 1500 Billet Silver Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 3 June 2018. Now at 69453 miles

Jeepwalker · May 10, 2022

Do these have fuel filters? Mine doesn't. Just a fine-mesh pick-up tube (screen) as I recall. Maybe that's an area of concern. But at low RPMs it should have plenty of power ...and would feel more restricted as more fuel was trying to flow through (but couldn't). You'd think there would be a fuel fault. Same thing could be said for the Cat. But if the cat were plugged or partly faulty, you'd think the computer would elicit a fault code (did you scan for codes?). Sometimes codes are 'soft codes' (like some misfire) and don't set off a visible check-engine light.

Would be good to hook up a real-time scanner and have a buddy drive it, to see if it is running in open or closed loop and what other readings might possibly be errant (vacuum, maf, O2, fuel, misfire, etc).

Sly Dvl · May 10, 2022

What does it do in park/neutral? Can you get the RPM up with no hesitation? A plugged exhaust won't be obvious until you bring the RPM up, and worse under load.

vududoc · May 27, 2022

Well its been back at the dealer. Right side LTFT at 0 and Left side at -1.59 and cold tick on startup SMH.
On another note the good old 3-2-1 downshift bump is getting checked and have a reference to ZF transmission shop if the current shop does not pan out.

Truck labored acceleration and feels like its towing a load.

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