Over the weekend I picked up a 1999.5 Disco II with 101k. Typical 3 amigos, sunroof leaks and dropped window seals.

But the thing I need to fix first is that when cruising steady with a steady throttle input at highway speed 50+ I can constantly feel the engine power gently vary, and then randomly the trans shifts from 4th to 3rd and back again. My assumption being the TPS is jumping around randomly and then jumping enough to prompt the trans computer to downshift.

I have a obd2 reader but the polling rate isn't very fast so it's hard to see if the TPS values are actually jumping.

Idles will randomly jump around too, sometimes up to 3k range.

Anybody run into this type of behavior?

Other than that I love this thing so far, ride is much better than I expected and it feels SOLID compared to my fleet of ****ty Subarus. Can't wait to get it dirty!

 

Start with figuring out your idle issue that kind of rpm surge is nowhere near normal. My truck sits solid at about 675- 680.

I would start simple :

• Check all your mechanical linkages on the throttle body - they should be clean and move freely
• Check all your hoses for leaks and/or cracks
• Air filter - clean and serviceable no rodents living in there
• Spark plug wires all good
• MAF looks clean connector on solid

If all of this is good try putting your truck in neutral or park when idling do you still get the same jump?
If not a transmission service would be a good idea, check the fluid for color and to make sure it is not "burnt"
Check your transfer case as well, make sure it is not low.

 

Got a replacement TPS in the mail and that is what the issue was.(14$ on amazon why not) Rover immediately feels better and once up to highway speed the light hesitation/bucking and random shifting is gone. Idle stopped shooting way up as well.

Previous owner did the plugs and wires new MAF and fluids when he got it in the fall.
Rodents definitely started eating the tube that goes from the airbox to the fender at some point, but that isn't critical.

 

There's a fix for that....

 

Yup! That amazon listing photo looks just like mine!
Thanks for the link! It wont be here before the flood watch in my area is over though... once every 20 years apparently.

 

Congrats on the new ride. Show her off..