when i have my CC on and set, i noticed that my RPM's occasionally jump up about 500RPM's and it sounds like my tranny keeps shifting gears. has anyone else encountered a similar problem or have an idea what's going on?
99 D SLT 4x4 5.9

when i turn off my CC and use my foot i can't replicate the problem. the rpm's stay put. i try and pump the accelerator to imitate the erratic rpms and i can't get it to do it.

 

Might be your trans output sensor. Have you replaced it yet?

 

99% it's the throttle position sensor... they get noisy and cause the torque converter to lock & unlock which show's up as an rpm jump.

 

Restlesswynd, that's it, and I'm also 99% certain based on what you posted. Bingo about replacing the TPS, throttle position sensor. I don't know about the "noisy" part on a sensor that Steve mentioned, LOL, but that is indeed the symptom/solution.

IndyD

 

the noisy part is when the resistance is varying too great and the pcm thinks the throttle is pressed farther than it is. it's 1st task is to unlock the converter.

 

So what is "noisy" actually?

IndyD

 

when the TPS is moving it's actuator thru it's range you should get a steady increase in resistance across 2 of the terminals... when its noisy, you loose that steady increase and the resistance will jump up towards to an open reading and back. they tend to do this because 90% of it's use is down in the part throttle range and it gets the most wear.

 

OIC now! It isn't an actual noise, it is resistance and 'noise' showing up on the voltmeter. Got it!!

I was honestly lost on that and since most here are shade tree mechanics at best, I'm sure others would have wondered, "what noise" as in what audible noise.

Thanks for clearly that up. And with that said, I wouldn't know where to start, to look, what to connect to or what to expect to see via norms or noise... AND I OWN A VOLTMETER AND A TPS (of course LOL.)

I say, "In with new parts! That'll fix it!!" LOL

Thanks Steve.

IndyD

 

lol, glad to help! [sm=icon_cheers.gif]