Dead spot on throttle, HELP!!!

[rockguy]

Hey good day.
My Runner is a 87' 22RE. Ive had alot of toy's over the years but this problem is peculiar.
I have a dead spot on the throttle. The truck runs fine when cold. But when it heats up, there is a flat or dead spot. It is the same while midly accelarating or cruising at highway speeds, but again is only when hot, or at least much more pronounced when hot.
I started to notice it when I could not hold one constant speed on the highway, eg 110 kph. The power would dive until I push far enough down on the throttle for it to pick up again, then accelerating faster than what I was trying to hold. So I'd back off on throttle a bit, only to have the power loss and quick decelerate issue.
So first things first, TPS right? Mine had a siezed philips head screw on the TPS. Also my throttle body has had over 500,000 kilometers run through it. Everything in it is loose and old. So I found a used throttle body that felt much more solid than my original, adjusted the TPS setting according to whoomever that awesome guy is that has all the help pages. Basically I used a test meter, and measured the resistances at closed, open at .57, open at .9 (I think) and at WOT. All seemed well after I adjusted it. Then I re-timed it to 5' BTDC. This throttle body seems much more responsive. But as soon as it warmed up, EXACT SAME ISSUE!!!! AAAAHHHHHHH.....
Now what? I have checked the resistances on the MAF. It's fine.
I dont know where to go from here. Any advice or help would be much appreciated.

 

[SV_Dude]

Usually if you have an issue with a dead spot or a power issue in a certain range of the gas pedal then it's a TPS. I would double check your TPS settings, maybe it moved a little when you tightened it. Did you just adjust your old one or get a new one? Sometimes an old TPS can check out fine but have a weak spring inside which will adjust fine according to the FSM but when giving it more throttle it will not act right.

 

[rockguy]

Hey Thanx for getting back to me.
The TPS I'm working with came on the throttle body that I bought used. The runer I took it from was a running truck. But on mine it ran like crap until I adjusted the TPS.
It took me serveral tries to adjust it and get it tight before I didn't mess up the readings. The only thing I didn't do was triple check the numbers when I bolted the throttle body back onto the intake.
It would be almost too coincedental to have two different TPS units doing the exact same thing. I'm not againts buying a new TPS if I have to, pretty sure I saw one on DAVES site for 80 bucks. But I really dont want to have to keep throwing money at this thing. Am hoping to do a V-8 swap this fall/winter. Just wanna keep it on the trails for camping/wheeling this summer.

 

[SV_Dude]

It wouldn't be likely that the tps got knocked out of adjustment with you installed the tb on the intake. Did you check the adjustment after you tightened the screws on the tps? I made one of these little doo-dads to make adjusting my TPS easier:

http://www.toyota-4runner.org/classic-t4rs/103377-showing-off-my-new-goodie.html

 

[rockguy]

Thats a handy harness you built there. Ive also seen that replacing the stupid phillips head screws with allen screws makes the TPS adjustable without pulling the throttle body.
And yes, after I retightened the screws, I rechecked all four positions, that I previously mentioned. It was a real pian in the ars to keep it steady while tightening it but third time was the charm.
I was just going over your runner build. Looking at engine porn now. So far so good! I'll havta get some pics of my own build up soon. Been ten years in the making now.

 

[SV_Dude]

Don't bother dumping money into your 22re. I have about 3k in mine and I regret every penny! I would much rather spent 3k into an engine swap. My motor is much more peppy than a stock 22re but it still only has probably 140-150 hp and probably somewhere in the same area for tq.

 

[rockguy]

That's a valid point. I'm planning on a 351W swap. Fuel injection for those is a dime a dozen and easy to install.
I had a built 22RE. Balanced and blueprinted. Line bored, shaved, ported and polished. Except the bas****s that did the head work for me oversized a valve seat. It failed somewhere around the 70k mark, sheared the valve which dropped into the cylinder. Destroyed my fancy pistons, ripped open the block, and destroyed my sweet ported and polished head. Needless to say that was the last straw.
This 22R I picked up from a rollover. Cost me nothing but time to drop it in and am hopeing it'll keep me on the trails until I can accumulate almost everything I need to do my 351 swap before I get started on it. I have a buddy who did this swap very succesfully already so he's my template. Fits better than a chev, narrower and distributers in the front.
Only used 22RE parts for this pig if I can help it. Just a few more months of wheeling to be had this summer, I hope!!!

 

[turboSR5]

Disconnect the TPS and see if you still have the dead spot. If you do, might want to check the thermal time switch, about the only thing I can think of that would act up when warm.
Have you checked for stored trouble codes?

 

[rockguy]

I did check for trouble codes. Came up with O2 sensor. I have a 4-1 header with the O2 sensor way down line in the exhaust past the collector. I get a warning light sometimes when I'm on the highway running at a constant speed. It goes away as soon as I blip the throttle so I'm thinkin the O2 code is from that. I 4got to pull the fuse on the weekend to reset the codes. O2 failures fail open anyways, which cause 22re to run rich.
I have no idea what a thermal time switch is. When I get time, I'll GOOGLE it. Is that something to do with fuel managment? And any advice on checking it?