TPS headache

I've been doing some work on my truck (1996 Tacoma 2.4l automatic) and have managed to mess something up so I need help. I think its the TPS gone bad but frankly - I'm not sure. Here's the full breakdown:

I bought the truck cheap a few months ago and got a new engine in it - the old one was thoroughly busted. The check engine light came on fairly soon, and I brought it back to the shop and we read the code and saw it was for the TPS - it still drove fine so I was instructed to get that replaced when I could but to not worry too much. That was about a month ago. The truck really did run fine - the exhaust has been a little gassy but the TPS is acting up so that makes some sense.

Getting to the TPS requires removing the EGR valve - I do that, I find the gaskets are pretty old, so replace them with new ones - (after buying ones that don't quite fit the first time - then finally getting the correct ones) As I'm cleaning the EGR I pull off once of the coolant hoses thinking its a vaccum hose - I quickly replace it but I don't know if that could cause other problems (getting air in the coolant system is bad I know).
All this and I find the new TPS i bought is set up to spin the opposite way - this is the second TPS I've gotten that was wrong, but whatever. I got them both on ebay so I haven't spent a ton yet. But things were fine so I figure I'll put it all back together and figure it out later.

But when its all back together - I went to start it and the engine revved way up - surged a few times - then the rpms dropped down and the engine stalled out. The throttle didnt' respond at all when the engine was on. (and it only stays on for a few seconds before stalling out) I must have broken something or maybe the TPS is finally fully busted. Could I have reinstalled something incorrectly? What would cause this?

 

First of all, a code for the TPS just means you need to test it first. It could be out of adjustment, a broken wire or the throttle plate is binding and not closing completely. You need to follow the instructions in the repair manual for how to test the TPS using a multimeter. There is also a procedure for how to install the TPS and set it correctly. It needs to be set so the computer knows precisely when the throttle is fully closed. What was the exact code you got?

 

I checked the TPS in there against the resistance readings in the repair manual. I don't have a way to apply vaccuum so I could only get two readings - and they both were lower than the book said they should be.

I must have gotten lucky the first time I took it apart and put it back together again?

 

The TPS doesn't move by vacuum. It moves when the throttle lever moves (when you step on the gas pedal)

 

I guess this isn't something I can do without a feeler gauge? I'm having. a hard time understand this bit and it's not a tool I'm familiar with, is there anything I should know about this?

 

You can open the throttle with your hand. No real need for a vacuum pump to open it.

Basically, the IDL-E2 circuit tells the computer when the throttle isn't completely closed. If the throttle is just slightly open IDL-E2 has no continuity (infinite). If it's closed it has less than 2.3 kOhms. You have to have the multimeter on the correct scale to read that or have a multimeter with an auto scale.

A piece of paper is about 0.1mm, so you could use a few pieces together as a crude feeler gauge to hold the throttle open like it says in the repair manual.

 

ok I got super confused by those instructions but I got it working again

I couldn't get the idl-e2 circuit to spike, it only went from 1.25k to 1.56k ohms (throttle closed to throttle opened)

while the vta-e2 went from 0.74k to 1.60k ohms
(I set the tps to this with the mounting screws. the far opposite install gave me 0.4k to 1.5k ohms)

this is why I was trying to replace the tps, since the resistances don't seem to line up with what they are supposed to

 

Take it from someone who has been bent over and thoroughly sodomized many times by those EBay parts, if it’s so inexpensive you say “holy crap, this is awesome!”, it ain’t. I’m done with that EBay garbage. Look at this amazing MAF. Genuine Denso! 27 bucks! Weeeee. I have no clue wtf it fits but it sure as Hell ain’t my truck as they adamantly proclaimed anybody want it? Send me a postage paid self addressed envelope. I ain’t sending it back to the idiots on EBay.

 

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Those readings aren't correct.

 

Get a scan tool that with read and clear codes and also read live data.
I had multiple TPS codes over the last year. Tested the sensor, checked wiring, cleared code and let it ride.
My junk is V6 but the sensor is similar.

What I found after watching it over time it would randomly had a dead spot at idle where the ECU wasn’t reading it.
After I saw it happen on the scan tool watching the sweep I could reproduce the issue at will by firmly closing the throttle. A light close may or may not show a dead spot. Mine set pretty regular on cold start up

TP% @0, should be 9.2-11.8% rest my foot on the pedal and it would not set

 

what do you mean? this lines up with what the TPS readings were off the truck when I first tested it - it wouldn't get up above the 5k ohms it was supposed to when the throttle was fully open

Was there a fix for this or did you just let it ride with the dead spot?



Also it turns out I messed up when I put it on the first time, the metal stop inside the TPS got bent out of shape and the whole thing lined up on the wrong side of the levers.

 

Yeah, here’s the listing

 

I replaced the TPS procured from Amazon sold by a Toyota dealer, was $53 and correct

 

Nice find. The best money that anyone can spend on these trucks is a scanner w/ live data. Never to be regret. Harbor Freight has decent ones for a hundred bucks. I bet there are guys here with hundreds in musical parts... me included.

 

That's the one that I'm running in my 3.4L. Does the one on your 2.7L looks different? I've got two spares already. So I'm fixed for MAFs.

 

The one that’s in there is square tube, and the mounting screws don’t line up. I think it’s like a Cardone brand or something. I will swing by the junkyard next time in that area. They warranty them and at least I will know it is genuine. I’m not screwing around w/ the remanufactured ones and I would have to pull an Oceans 11 at the dealership if I wanted a new one.

 

Does yours look like this? I see this listed for the 2.7L and 2.4L

 

Yup. That’s what’s in there.

 

Alrighty.. I think you have one for a 3.4L and need one for a 2.7L / 2.4L.

 

That scan tool was $60 on Amazon