4l60e rpms jumping up and down.

tbauer03

tbauer03

TRBOBOX
When I was driving to wal-mart the other day, a brief drive down the highway, the truck would quickly jump from 2k to around 3k while driving around 60mph on the highway like it was down shifting then quickly up shifting back or the torque converter was unlocking then locking. This was brief and I got to wal-mart and back home without any problem. Today I grabbed my laptop and drove the truck to work which is about 12 miles away, all highway, to see if it would act up again and that way I could document it. It drove about 3/4 the way there without problems then it started acting up when I was close to work. Below are the pics. To me it looks like the TPS input is off because it is very volatile and I know I wasn't feathering the throttle back and forth like that. My guess is with the throttle input being off it is triggering the car to down shift and to let the torque converter slip. But these are just guesses. I will probably start by recalibrating the throttle sensor but after that I am confused to why it would drive down the highway just fine for the first 3/4 of my trip to work then act up when I am just about there. Anyway any suggestions or answers will be greatly appreciated. Thank You
Normal driving down the highway on the left and after it started acting up is on the right
Green = MPH
White = RPM
Blue = Current Gear
Grey = TPS
Yellow = TCC Slip%

4l60e1.jpg

4l60e2.jpg

4l60e3.jpg

4l60e4.jpg

4l60e5.jpg
 
Houseofperformance

Houseofperformance

switchhappy!!!
Re: 4l60e rpms jumping up and down.

the trany seems to work properly, considering the fluctation in your tps signal - check the tps sensor and cable connections - guess the sensor is bad
 
BMFB

BMFB

Not to scale
Re: 4l60e rpms jumping up and down.

the tps flux is strange,

a simple thing you could do is drive it again and if it starts doing it downshift it manualy into 3rd, if it just sits at an rpm then you know it was downshifting, if it keeps acting goofy, you could look at the TC.

I had a very simular thing happen to me when my thermostat went out, it would stay warm enough on a surface road to keep the coolant temp above the low lockup temp (147F ish) but when I would get on the highway the coolant would drop below that point and unlock the converter, but it would usually go back and forth for about a minute (or much more time it seemed like somtimes) while it went past the threshhold.
 
syclownz

syclownz

New member
Re: 4l60e rpms jumping up and down.

Subscribed! Would like to see how this turns out.

My truck is doing the same thing. It does an 1000 rpm jump while driving and in idle. Tps is usally off by .03 digits even with a new tps. Figured that was normal.

Good luck and hope it's nothing serious.
 
1

1BADV6

Donating Member
Re: 4l60e rpms jumping up and down.

I'm curious about your 4L60E swap, what year trans did you use and what controller? Did you use a one piece trans with the proper bolt pattern on the rear or a two piece trans with the 6 to 4 bolt adapter?

thanks
 
tbauer03

tbauer03

TRBOBOX
Re: 4l60e rpms jumping up and down.

Quadrajet72 said:
The thread referenced has to do with TCC engagement. TCC lock/unlock is about 300 RPM difference. Ted's problem is a 1000 RPM difference.
But to me, the TPS seems "noisy", and the other systems are reacting to that TPS "input". Hard to believe it's moving that much. And the other thought is, is the engine RPM really changing that rapidly up and down?
DaveP
Click to expand...
The day from my last post on this topic I disconnected the tps wire from the throttle body, cleaned it out, and reconnected it. I then drove it about 13 miles all highway to my parents and it never acted up. Unfortunately I took the wheels off of it to get refinished before a car show but the shop has taken a lot longer than they thought to finish them so it has been up on jackstands waiting for the wheels to come back. So I haven't driven enough to be convinced just cleaning the tps connection has solved all my problems. Sorry for delaying a status update, I appreciate everyones comments.

OK. Now that you have me looking at this. Next time you log this, put a graph in for MAP as well as TPS. If MAP and TPS are noisy silmotainously, take a look at the 5V signal voltage, and the sensor ground at the ECM
Also, what are we looking at in the graphs? A log of the trans controller, or of the engine ECM?.
Click to expand...

The graphs you are looking at are from the PCS Transmission Controller Datalogger. I will see if i can post the graph with MAP represented.
 
tbauer03

tbauer03

TRBOBOX
Re: 4l60e rpms jumping up and down.

mapvstpscompleteview.jpg

mapvstpszoomedin.jpg

Map looks normal to me.
I am pretty sure this just wiring issue with the TPS signal. This truck has been notoroious for electrical gremlins because it sits for long periods of time. I am hoping the bad connection was the culprit and the cleaning was the correct remedy.
 
Buzzmanb12

Buzzmanb12

NEWB
Re: 4l60e rpms jumping up and down.

More info-- Any time you get rpm jump you should check out the ignition system. I have seen a few with the same issues (mine included) and it was either the plugs, plug wires or the distributor---all easy fixes that don't require a bunch of guess work or money.
 
Windedv6

Windedv6

Ty n 10s
Re: 4l60e rpms jumping up and down.

Make sure the Vss and the tss line are not switched from front to rear. My loom was marked incorrectly and i had fluctions around the shift points. Finally figured out the plugs were reversed and ended the problem.

John
 
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