Here is the stats, I have an 85 4runner that has the intake, throttle body off a 89 or newer. Since the rebuild and getting it back on the road I have had a bad IAC. Today I pulled the throttle body off a 91 2 wheel drive. I know the dash pots are different between the 2 wheel and 4 wheel drive but other than that I think they are the same. The throttle body off the 2x came with what appeared to be a good TPS with a nice looking connected. And mine is shot.

I got home, tested the TPS, it tested good. Removed the TPS, cleaned the throttle body/IAC real good. Installed the throttle body, grafted in the new connector to the old wires, hit the switch. The new throttle body started at a normal cold idle, quickly warmed up and dropped down to 800 rpms. No codes from ECU. I thought all was good, cleaned up the tools. Then hit the throttle, that's when the problem was noted.

When the engine comes off idle it surges between 1500 and 2000 rpms. It acts like the ECU is hitting the fuel shut off at a constant rate.

It does the off idle surge with the TPS connected and disconnected.

So far did the check engine light test on the ECU, it test good. All fuzes are good.

Any ideas, will a 2x4 throttle body work on a 4x4?

 

I put the upper intake & throttle body off a 93 2wd on my 87 runner. However I ran my old TPS. No problems.

I used this site for info. http://siestaoffroad.com/tbody.html

 

I've been told that the TPS requires programming and that unplugging it deprograms it. I have not dealt with this on Toyotas, but have experienced this with my prior VWs.

 

Yeah I'm starting to think it just doesn't like the TPS off the 91. But that doesn't explain why it did it also with the TPS unplugged. So far I have checked the resistor, circuit opening relay, main relay, fuel pump by pass at the AFM. All checked good. Rechecked that wires for the 91 TPS are the same as the 85, and hooked up right. I have a spare ECU, so I put it in and it started up and ran good, but was throwing codes 2 and 5. I have no idea f that ECU is good or not. I think I'm going to put it back origiinal and start over.

 

I hate these threads that don't have a conclusion. So I figured I would post up. I had two extra ECU's that I got from a pick and pull a while ago. Ince I was in there I figured I would hook up the third one which looked really nasty, just to see if it was any good. The runner started up fine, and runs through all the rpms just fine. No codes. Just all coincidence I guess.