Renix TPS adjustment confusion...

Alright, people who have experience with this... I've adjusted the TPS on my '87 4.0 5-speed to 0.78 volts at closed throttle, which is almost exactly 16% of the 4.86 volts I get on the input side. Does this sound good? The difference is about 84%, searching on here on the site I've seen people claiming they've set the difference all the way to about 90%. Should I set the voltage higher, lower, leave it where it is? I'm a tad confused, as the factory service manual says "set to 0.8 volts" and has no mention of any kind of percentage of the input voltage, but searching on here I find that people recommend anywhere from an 80% to 90% difference. What's the correct way to set it?

I'm hoping that adjusting the TPS correctly will solve the driveability problems I'm having... basically bucking and sort of wanting to stall for a second or so after I shift (5 speed) on the highway or when accelerating to achieve a bit faster speed on the highway.

I'm wondering if maybe I should ignore the 84% thing and just adjust the output to be exactly 0.8 volts with the throttle closed?

Any tips anyone?

I really don´t think 0.02 volts is gonna make much difference. I´ve adjusted mine anywhere from 18-12 %, around 14-15% seems to work well.
If your bucking at around 2000 RPM and it seems like you can accelerate through the bucking. I´d think about a O2 sensor. Mine was bucking, especially at lower vacuum (accelerating) at a round 2000, O2 sensor was most of it.
If it´s happening consistantly at around 1/3 throttle, I´d think its probably the TPS. My TPS had a hitch at around 1/3 throttle (there was a service bulliten for this). worked well most everyhwere else. I could see the hitch, with an old analoge (needle type) ohm meter.
Most of my bucking and snorting, has been related to a bad sensor or a vacuum leak. Vacuum leak will usually mess with your idle some.

The idle is good, no vacuum leaks to speak of. I actually just finished putting a new exhaust manifold on, cleaned the throttle body and other pieces up a bit, just to see if it would make a difference, but nothing. This has actually been a problem since I've owned the jeep (almost a year and a half now), but it seems to come and go... one day I'll be driving along thinking "gee, it hasn't been bucking in a while"... next day it'll be doing it.

Anyway, I'm pretty sure the TPS is good... as it does this with all three of the TPS's I've tried (all used ones, however), and in the same manner all the time.

I'm going to go with your suggestion and replace the O2 sensor (shoulda done it when I had the manifold out... but I was in a hurry to get it back together), and adjust the TPS down to 15% or so, and see what happens.

the factory updated the specs for the tps for some performance concerns, the recommended setting is 12 - 14%. that basically corrects idle concerns though. if you are having problems with surging or bucking after replacing the o2 sensor, you need to make sure the distributor is indexed properly. you could be getting a crossfire condition.

My 87 4.0l Auto is having similar issues, sharp drops in RPM as if it's going to stall while at 1/4 throttle. At first I thought maybe the fuel filter but that didn't solve it. It runs great when it's cold but when it gets to op temp it gets horrable. It's been getting worse for the last few days. Having the Heater on seems to aggrevate the situation as well... Thnx.

That's EXCATLY what mine's doing too...I searched for "crossfire" and I am a little confused as to what this is. I just replaced the IAC, TPS, plugs, wires, O2 sensor, cap and rotor....STILL DOES IT!!

Egr valve mine went and the thing ran very poorly try unplugging the vaccuum to the solenid mounted next to the ballast by the air box and cap it

Yup...that and indexing the distributor are my first two chores in the morning!

I have a 88 XJ and decided to replace the TPS as part of my sensor replacement program. I replaced mine around 130,000 miles. I found the XJ ran better with a new TPS.

I took the XJ into the shop because of low MPG problem which turned out to be a sticky EGR valve. The mechanic told me my TPS was out of range even thought I had used a multimeter to set the value.

I then purchased a snap on MT2500 off of Ebay, it the only scanner beside the dealer tool you can use on a Renix XJ. The scanner reads the value seen by the computer, not the measurement at the TPS. The multimeter method does not take into account the voltage drop form the TPS back to the computer ground.

The multimeter method is better than nothing, but if you can get someone with the snap on tool to set your TPS for you. I'd do it for you if you lived near me.

I think I figured it out... After speaking with a few local mechanics (Actuall mechanics not the dealer drones) I figure that my Stator is pooched... It's all good when its not warm, but when it gets wam, the engnie sputters... But only at 1500RPM, above and below it's all good. New stator is about $116 CAN but I'm going to get a whole distributor from the junker for $75 and see how well it workd first... Gimme some time and I'll post up if it fixes it, Otherwise anyone else out there having the same prob... It's something to look at.