toyo22r

The wife took kids to the state park for swimming. On the way home she had to go up some rather steep hills. She said that the 4Runner would barely climb them at 10mph, with AC off....

I suspected the TPS. As i seem to remember reading a failed or mis adjusted one would cause the symtoms of no power off the line. I shorted TE1 & E1, and just as suspected there was no change in the idle speed, another symptom of a bad TPS. When I put the timing light on it the mark was lined up 'most' of the time, but you could see it jumping all around... it did this with and WITHOUT the check connector shorted.... is this yet another symptom of the TPS?

I tried adjusting it, but doesnt seem to want to hold it... I had it adjusted, shorted the check terminals, idle went down as it should, but by the time i got the timing light hooked back up it was back to idling higher as if the connecter wasnt shorted... I'll pick up a new one tomorrow at the dealer... but i guess what i am getting at is.. will a bad TPS cause the timing marks to jump around like that, or is there something else wrong i need to look for.

Thanks,

toyo22r@hotmail.com
95 4Runner
St. Louis

trythis

Yes, your timing could be impossible to set with a bad TPS, depending on why it is bad, but yes, that can happen. Well it did for me.

toyotaoffroad91

how did u make out im mine is sort of doing the same thing

toyo22r

Well i readjusted the tps, after checking it, it wasn correct... i think my feeler gauge must have slipped. I wasnt able to do a long test drive, but my wife took it to work and claimed it ran great, better than before.

I also called a Toyota tech who said that when the connector is shorted, the timing will retard just a couple degrees (which i observed) and also said that most of the time you cannot hear the change in idle. Which i still think is odd... with my Camry there is a noticable difference in idle with the check connector shorted.

trythis

The problem with a bad TPS is that you can set it and drive for a minute, an hour, day or even a week, but it will fail to stay in adjustment. If the thing doesnt stay, just buy a new one. They are $100 or so but make a major difference in how the truck drives, especially with an automatic, as gear shifts are controlled in part by the TPS signal.

Snorkeldepth

With all the talk about adjusting the TPS, I was wondering . . . . . if you buy a new one does is come adjusted correctly?

trythis

nope, the adjustment is made by positioning it on the intake body. It rotates a few degrees. Change out the phillips screws with socket head cap screws so you can adjust it on the engine, if you want to make it easier in the future. If you take it off and the spring loaded dealy-bob in there doesnt snap back, You'll need a new TPS.

You also want to make sure the intake flap is closing ALL the way. Mine had carbon build up keeping it from closing and the TPS never reads at 0 position. It is amazing how much gets screwed up if your TPS is off by a little bit.\
Your EGR system blows exhaust, and nasty fumes into the intake plenum just behind the intake body (even though it is located on the back of the engine). Carbon just builds up there.

Snorkeldepth

I'm a little concerned about my throttle body. The throttle sticks every morning to the point that I have to break it loose. I had the TB thoroughly cleaned when I put the new engine in. I was suprised that it's still sticking. I've heard that a small groove can develop in the body that the flap gets stuck in. I think I recall that a bit of fine emery paper can do the trick to fix this. I wonder what all of this means as far as the TPS on my truck. How do you determine that the flap is closed "all the way?"

trythis

I could tell that it wasnt all the way becasue I could close it more by hand that the springs could do alone. I could force it into the carbon guck, but I had ot spray it with TB cleaner and wipe it down. I dont see why a little LIGHT sanding would hurt except if you did it on the plenum, as metal bits might go into the intake.