Car bucks back and forth when letting off or barely pressing gas pedal.
 

If I slow down in first, once I'm under 2500rpm the car starts jerking, then if I get back on the throttle it's pretty violent. Same for second gear, but not as bad. Because of this, I always just put my car in neutral when slowing down in first because it's incredible annoying and most likely embarrassing. I've adjusted my TPS a billion times because it keeps undoing itself. A quick google search brought me to other forums where people are told it could be TPS, engine mounts or sticky throttle cable/throttle body.

It's been doing this for a while and I've ignored it until I finally got a multimeter and fixed my idle, which did stop the car from bucking while in low rpms while slowing down, but it still does it randomly and very violently in first and sometimes second. Actually now that I think about it, it evens does it in 3rd and 4th when slowing down for lights, then it turns green. When I get back on the throttle lightly it jerks a tiny bit.

I'm terrible at explaining things, so if anyone understands and has advice, it would be greatly appreciated.

New fuel filter and clean injectors once I get paid next week. I'm doing a full 100k maintenance because I'm only getting 11 mpg city on an otherwise stock '91 N/A (exhaust and HKS intake). I've only got 98,000kms on my stock engine/body so I doubt most of these things have been changed in a while.

Same shit for me, everyone said TPS. Mine seems fine when testing, but I got hold of a new (used) one tested to the correct resistances. My injectors I know are fine, fuel filter was swapped some years ago, but few miles, maybe 10k or so.

So even after all these, it still does it?

I had that, it's your TPS. There's a dead spot in the range.

What do you mean by "the TPS keeps undoing itself."

Poor choice of words, aha.

Basically I adjusted the TPS the first time, it was at around 500, I brought it up to 1000, then when WOT it went to 4k. I went for a drive, came back and it was slightly off again, so I adjusted it again. Two days later I checked it again and it was at 800, adjusted to 1000/4000 again and then went for a test drive and came back and it was fine. A few days later, I checked again and it was at 900, adjusted to 1000 again and that was yesterday.

Will buying a TPS from a parts car solve this? I have no clue what to do when it comes to wiring anything and don't have the tools for it, so I guess I'm shit out of luck? No way I'm buying a new one for 400-500 bucks. I have to work a full month to make that. /college

A new one actually cost two bills from a place like Rock Auto, which are identical to the factory supplied units, but you shouldn't have to go that route. You might have better results by setting the TPS to 1 volt w/key to on at the Green/Red wire and engine completely warmed and under no other conditions at all so checking the setting when cold is a no go.

How do I set the TPS to 1 volt?

Everytime I adjust the TPS to 1k it's always when the engine is fully warmed up and after a drive.

You shove the Red meter lead into the back of the TPS plug (plug is connected to harness) and the Black meter lead goes to a ground such as the battery negative terminal. W/the meter set to DC volts you see what the meter reads w/the key to on and engine as warm as it's going to get. If it reads other than 1 volts then a flat head screwdriver turning the adjustment screw will take it to 1 volt. A pic of the adjustment screw is in the link below. It's surrounded by a spring, one inch in length and closest to the TPS rod that extends from the unit.

Post #8.

https://www.rx7club.com/2nd-generati...blems-1010483/

Still waiting on the new TPS, so if it ain't better, mine is still fine (to the degree I could check it (volts) would not cover everything, ohming is the other way). If it ain't the TPS, fuel filter or injectors, I am really wondering what it could be, because this is getting annoying :P

Randomly enough mine only jerks when there is a nice lady in sight (or the occasional butterface, from the rear, I may add)

Satch, what did you use to backprobe the tps? I couldn't even get it far enough down with a clothing pin...

I still have no clue how to check voltage. I plugged the red lead to the green/red wire on the TPS sensor and then the black to the negative battery terminal and I don't get anything. I don't know what I'm doing wrong but I'm just getting tired of this car.

The key needs to be on. Do you have the key to on. Do you have the meter on? The meter lead itself gets shoved into the plug. And as it states in post #12, the plug is to be connected, which is the opposite of not connected.

So just push through the wire with the sharp end? I have a Fluke meter and the leads seem to be like 2mm thick, which won't fit down between the wire and the rubber grommets protecting the pins.

Just push it. But be aware, I destroyed my connector doing that, had all the TPS issues you find on these forums together at once. Swapped for 6 single pin connectors, boom, all problems gone!

put a locknut on your TPS adjuster screw and set it again.. if you've adjusted it that many times i'm quite sure the threads are as loose as a veteran hooker.

I lost the nut on the TPS, so maybe that might have something to do with it... Woops. I dropped it while it while I adjusted it the first time. Could anyone tell me what the nut size is for the TPS on a '91 N.A

Adjusting the tps by voltage is better than adjusting by resistance.

If you have a rtek, you can adjust the tps to 20% at 750-800rpm which is exactly 1 volt.

On a stock ecu, I try and backprobe it near the ecu. I get a 20-22 gauge wire and strip the ends off and then slide it into the back of the TPS wire on the connector.

My TPS was at 1.0xx volts. I didn't even need to adjust it. TPS seems good! So as others have said, could it possibly be fuel related? I'm ordering new plug wires, plugs, fuel filter and changing engine oil, diff and trans oil and brake/clutch fluid. I will get my injectors sent out to be cleaned on another paycheck. But I don't see how I could accomplish that considering my car is a DD and go to school 5 days a week and work 5 days a week.

have you ever done a TPS sweep test?

Not sure what that is. All I've done is got the TPS to 1k ohms and then checked the voltage and it was already at 1.

It requires an analog meter so as you open the throttle fully so you can see the meter needle move in a smooth continous manner free of spikes from low voltage to high. Rather hard to do w/a digital meter.