closed loop ????

[Hellcat]

Here is my issue
Cruising at roughly 3000 rpm. My 92 4.0 auto runs great, add a slight load like pulling a hill and I get a 500 rpm
Surge. It's just like a light switch up 500 down 500. I have tried running the same rpm. In different gears and not so much as a blip.
I don't have a scanner for a generation 1 system and neither dose any of the parts stores. I am thinking that maybe the 02 sensor is causing the truck to go into and out of a closed loop. Any ideas ????
Thanks

 

[n_grimm]

Could it be that the torque converter is locking and then unlocking when under a load?

 

[97RangerXLT]

Gonna second Grimmy's opinion. your truck is 'hunting' the correct gear to be in. under load it needs a bit more oomph to make the incline and you are very close to the shift point, so it unlocks the torque converter and downshifts, then when it realizes it needs to be back in the gear it was in, it does it again to upshift. pretty normal. Most likely this is yoiur drive/overdrive gear that it is hunting in.

The reason it does not do it in any other gears is because you are forcing it in a gear lower than what it would normally run, so it stays the same rpm (does not need to downshift)

Hope this helps

AJ

 

[Hellcat]

OK
Finally found a code reader. Showing low voltage to TPS the TPS is a month old. What would be causing low volts? Could this be part or all of the issue
Thanks for the help so far

 

[Hellcat]

Got Lucky

Went to three shops got three different diagnosis
1. Bad PCM
2 Bad Transmission
3. Bad! Torque Converter
I just didn't buy into any of the three. I found a good write up on testing your TPS. and testing your IAC. The TPS was a month old BUT I am at whits end. I replace TPS, clear codes unplug IAC set idle at 500 RPM plug IAC back in RPM goes to 750. According to article that is right on the Monet. Clear codes test drive AND TADA
Runs Great problem solved.
Got Lucky.

 

[97RangerXLT]

Cool! Glad you got it fixed. And thanks for posting what fixed it


AJ

 

[Hellcat]

Cool! Glad you got it fixed. And thanks for posting what fixed it


AJ

Not a problem as many things as I have picked up from this. Site it is nice to be able to offer something that may help someone else