Quick background I've have the truck since November 2022. Have always noticed it sort of struggled uphills. Infact my 5.7 c1500 seems to tow better for this reason. It's just not quick off the line in any sense and struggles uphill especially towing. Recently bought a dump trailer this week and at 3660lbs it really was having a hard time. Which I don't think it should since it's rated to tow 8500lbs. I can imagine throwing 2k lbs of dirt in the trailer and not being able to make it up the smallest of hills. 2 months ago replaced the transmission with a new reman. Have changed nearly every sensor in the truck. New injectors, new fuel filter, new fuel pump as of November 2023. Have not done a tune up since owning it. Is that the culprit of the low power or am I missing something?
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97 C3500 4L80E drops RPMs struggles going up hills.
- Thread starter MattP
- Start date
Also random side note, every single time I start my truck the gas pedal is stuck. You have to actually kind of give it a quick stomp to get it going. Once moving it doesn't happen again. Turn it off and turn it right back on the gas pedal is stuck again. Any correlation? Anyone delt with this before?
dbrannon79
I'm getting there!
Tell us what engine you have, what your RPM range is at a given speed under normal driving and how it drops under load. we might also need to find out what the rear end gears are in your diff. this can be engine or trans related. are there any codes on the PCM. service light can stay off and still have a code, just depends on what code it is. usually trans codes won't turn the light on unless it's really bad.
350 5.7 Vortec engine, RPM about 3k at 75mph hit a hill on the interstate and will drop to maybe 2500 RPM if that. Sometimes won't even drop it'll just slow down to about 60. Haven't checked for codes in a while but last time I checked there was nothing. Brand new PCM in March, checked in April and had nothing on it. It's been doing this for a lot longer than that tho. As for rear end gears its 4.10 ratio. Side note I'm not shifting into 3rd for any hills. Only pulling about 2600lbs right now on a daily basis
dbrannon79
I'm getting there!
I went back and looked at your "No Communication" thread and found the pic of your truck and what engine. 5.7l (350) gas truck with oversize tires and wheels. looks like a quad cab 4 door, nice looking I might add... that is a lot of truck for a 350 gasser truck depending on what rear end gears you have. your truck empty most likely weighs around 7,000 lbs. mine with the 6.5 diesel weighs 7,500 empty.
dbrannon79
I'm getting there!
you beat me to it LOL..
what grade of fuel do you normally run? the 4.10 gears the 350 should have decent power for pulling but it won't get off the line easy same as for our diesels. you might want to pull a plug or two and have a look at them to see their condition, also check your base timing. not sure if they left the timing marks on the front cover for these engines or you have to time it using the computer.
is your gas pedal electronically driven or does it use a cable to the throttle body? most of this and newer era will be electronic drive by wire. there is a GM TSB out somewhere on the newer one (not sure if your's is in with it) where part of the tune-up process is to pull the entire throttle body and clean it using some brake cleaner or berrymans b-12. If that has never been done, your gonna find that it's pretty gummed up with carbon and muck. after cleaning and re-install, you will have to reset the PCM so it will re-learn the engine.
are you familiar what they call an "Italian tune-up" ? it involves taking ether a bottle of water or a can of b-12 (liquid your can pour) having the engine at operating temp, and with one hand holding the throttle open at a higher rpm while the other hand slowly pours the liquid down the yap. this will clean out all the carbon built up in the combustion chamber. BUT don't do this if you don't know what your doing. pouring too much or too fast can cause hydro-lock and ruin your engine! it's an old school trick to blow all the cobs out.
Since you don't know the last time the plugs were changed, I would start there along with pulling and cleaning the throttle body. then we can move on to checking things like fuel pressure and other easy stuff to rule out the engine as the problem.
what grade of fuel do you normally run? the 4.10 gears the 350 should have decent power for pulling but it won't get off the line easy same as for our diesels. you might want to pull a plug or two and have a look at them to see their condition, also check your base timing. not sure if they left the timing marks on the front cover for these engines or you have to time it using the computer.
is your gas pedal electronically driven or does it use a cable to the throttle body? most of this and newer era will be electronic drive by wire. there is a GM TSB out somewhere on the newer one (not sure if your's is in with it) where part of the tune-up process is to pull the entire throttle body and clean it using some brake cleaner or berrymans b-12. If that has never been done, your gonna find that it's pretty gummed up with carbon and muck. after cleaning and re-install, you will have to reset the PCM so it will re-learn the engine.
are you familiar what they call an "Italian tune-up" ? it involves taking ether a bottle of water or a can of b-12 (liquid your can pour) having the engine at operating temp, and with one hand holding the throttle open at a higher rpm while the other hand slowly pours the liquid down the yap. this will clean out all the carbon built up in the combustion chamber. BUT don't do this if you don't know what your doing. pouring too much or too fast can cause hydro-lock and ruin your engine! it's an old school trick to blow all the cobs out.
Since you don't know the last time the plugs were changed, I would start there along with pulling and cleaning the throttle body. then we can move on to checking things like fuel pressure and other easy stuff to rule out the engine as the problem.
dbrannon79
I'm getting there!
other things you can check fairly easy on the trans is checking if your TCC (torque converter clutch) lockup is working in both 3rd and 4th. just drive at a cruising speed in both 3rd and 4th, while cruising steady (not up hill accelerating) tap the brake pedal just enough your brake lights would turn on and listen to the engine and feel for the TCC lockup to release. your RPM should increase by about 200 or so and go back down.
you want to make sure it's releasing and engaging properly when the PCM is commanding it. it should happen almost immediately when you touch the pedal, take maybe a second or two and then lock back up.
you want to make sure it's releasing and engaging properly when the PCM is commanding it. it should happen almost immediately when you touch the pedal, take maybe a second or two and then lock back up.
Converter locks up it's a new reman haven't had any issues with it since putting it in. Did infact go scan it and got p1122 code. TP intermittent low voltage. That's a new TPS so I just pulled it out and while in there took the throttle body off. Throttle body was caked in carbon causing the pedal to stick. Since cleaning and adjusting the TPS it doesn't stick and is more responsive to the gas pedal. Changed the air filter as well, going to grab the parts for a tune up then hook the trailer up and go for a drive.