1999 C1500 Suburban either hesitating or shifting only in a slight pull going down road seems fine in a harder pull

[jefflroberts]

I have 1999 C1500 Suburban with 5.7 and it is either hesitating or maybe the transmission is "hunting"? I can't really tell because it is pretty subtle but it is enough to be annoying. It only does it when it is in a very slight pull. Taking off or accelerating everything seems to be fine. It has a reman engine with less 5k miles on it and the CEL is not on. I checked the transmission fluid and I had to add a little but it did not make any difference in the problem. Could anyone tell me a good place to start with diagnosing this? Happy to provide more information and thanks in advance!

 

[thegawd]

test your tps it could be faulty and reporting incorrect data that the computer just believes. I had a hesitation like that and it only occured at a certain speed, 95 k/hr. but it wasn't the speed it was how far the throttle was opened.

On my cheap innova I click on live data and scroll down to tps. highlight tps and click on it. now I can see a graph. the graph is supposed to rise absolutely smoothly while the throttle is opened. if it does not or like it my case has a spot that is just blank and reporting like the throttle is closed. any waiver from a smooth graph line and the tps is faulty, so much rides on this correct info, fuel delivery and shift points.....

the truck dosent need to be running to do this test just need the key in the run position. this might deplete your battery powering the scanner so keep that in mind. with a healthy battery there really shouldn't be any concern.


good luck.

Al

 

[Schurkey]

As said, connect a scan tool and verify the sensors. TPS, MAP, O2 and Knock sensor for sure.

When driving, use the scan tool to assure what you're feeling isn't the torque converter clutch disengaging.

 

[Pinger]

Add MAF sensor to the check list - it influences transmission behaviour (and not just shift quality).

 

[jefflroberts]

Sorry for the late reply. I have a vxdiag that connects to a laptop running the tech tool virtual software. Could any of you point me to some tutorials or how to's to test those sensors? I can probably find it in the menu, but I am not sure what the normal readings vs having a problem would be. Thanks again for the help!