TPS help!

99 Tacoma 2.7 4x4 manual
Is there a method for the computer to learn a new TPS? Or did I do something wrong on the install to cause the situation? I’ve looked all over googling everything I can and can’t find anything to help.
The situation:
Truck had been idling poorly and getting crap mileage so I took it to a shop and was told my TPS was bad. So I put a new one in, but unfortunately the new one has made things worse. When it’s not under load it will surge to about 3k rpm and slowly lower to about 900. It jumps around idling then between 750-1100. While I was test driving it after the install if I cruised at 1900 or so I didn’t even need to use the throttle because it basically drove itself. Under load it’s fine-ish but as soon as I hit the clutch it surges to about 3k rpm again.
Not sure where to go with this. I drove it 2 miles after the install and then came back and decided to let it sit and idle for 30 minutes and did the same 2 miles with the same results. Any help?

 

TPS = throttle position sensor right?

 

Correct

 

You're not talking the common surging and then settling down like when the battery is disconnected for a while? Otherwise vacuum leaks or something left unplugged? Double check the grounds? Also was it an OEM TPS?

 

Interesting. I didnt know about the battery being disconnected problem. Could you elaborate? I had it disconnected for about 24 hours waiting for the sensor to come in.
I’m going to triple check vacuum lines tomorrow. Should be OEM but that’s also me relying on the sales guy telling me it was OEM. I’ll double check that as well

 

Just that the ECU needs to remap the fuel trims to your altitude, etc... It could be a few trips or cycles on and off of the engine. But it surges up then slowly works down but will stay generally down.

 

Interesting! I have never heard of leaving the battery unhooked for too long. I will definitely try taking a few more trips with it and see if it does anything. Thanks for the help!

 

It's not a problem. It's just what happens when it's disconnected for an amount of time. It's normal.

 

Because you disconnect the battery for 24 hours the ECU has been reset or should I say cleared of the ram info,

So depending it can take anywhere from 50 to 200 miles for the ECU to be completely reset (learning period) and the truck might run crappy for this period.

To help the process let the truck idle for 10 minutes from a cold start and do a few full throttle pulls ( high rpms) then drive it normally.

For me this seems to speed up the relearning process a bit

 

Hopefully everything is running good for you by now. If it's not, then we have some troubleshooting to do and you'll want your OBD2 scanner on hand

 

Was out deer hunting all day so didn’t have much time to run it. Ran it when I got back tonight and have gone from super high idle to a low idle at about 550-ish. Hopefully tomorrow I can take it for a road tour and see if that helps!

 

I'd say its pretty weird if it went all the way to 3k RPM.. I've never had that happen on my v6 (Park/Neutral equivalent since I have an auto).
ECU takes about 1-5 seconds to clear with battery disconnected, FYI - not very long at all. But that shouldn't cause an issue at start up since you'll always been open loop (internal map, no computer correction) for that time anyway. So disregard all the talk about altitude correction, etc.

It just sounds like you IAC is hyperactive lol. My truck does idle a lot higher (granted like 1800 max) when the coolant isn't warmed up yet, and that's a natural result of the IAC adding more air to to get your engine up to temp. Not sure why this would be a new thing for you though :/

 

It’s only been the one trip, but looks like it’s smoothing out. Put in 100 miles with a mix of highway and gravel and was running like a top. Idle was a little low at times, probably about 600, but I’m hoping that will come around. Averaged 20 mpg so I’m definitely happy with that. Like I said it’s only one trip so I’ll see if it holds up. Thanks for the help guys!

 

600rpm is perfect

 

1800rpms seems very high, my truck is mostly around 1200rpms for warmup

 

Did you install the TPS according to the procedure in the repair manual? I'm not sure about different years, but usually you have to position it so it can sense precisely when the throttle is closed (at idle position).