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Old 03-10-2009, 07:28 PM   #1 (permalink)
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'91 22re runs better w/o tps

Hi guys, my '91 2wd 5sp 140,000m 222re has recently started hesitating in the upper rpm range. There is a dead spot in the pedal between 1/4 and 3/4 throttle. Then if I floor it, the engine has full power. Idles great, starts fine. The vamf spec'd out bad , so I replaced it with a rebuilt from auto zone (which measures fine). The temp sending unit measures fine, and the tps measures fine. I have read all of the posts about hesitation that I have found, and one user unplugged his TPS. When I do this, the truck performs great in all throttle positions. The computer self diagnosis blinks on off, so its' not sensing any codes (until I unplugged the tps). I would not have thought it would even run without the tps. Will this harm the engine? Any ideas what the problem could be? This truck has not had a catalytic for the past year.
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Old 03-12-2009, 07:59 PM   #2 (permalink)
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Has anybody experienced this?
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Old 03-13-2009, 12:42 AM   #3 (permalink)
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Maybe sb5walker will chime in on this. He may know. I wish I could help but I really don't have a clue as to why it would run better with it unplugged.
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Old 03-13-2009, 09:27 AM   #4 (permalink)
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I hope someone chimes in. I bought my 94 22re w/ header and 2.5' no cat and after reinstalling the throttle body and my TPS has been out of adjustment. I tried to adjust it w/ the feelers and multimeter to know avail. I just adjust it until it feels right which seems to change w/ temperature. It is easy to get it to run great at a couple throttle positions but seems very difficult to find the sweet spot where it has good response at all positions I have not been able to get more tan 22.5 mpg in town w/ spirited driving to say the least I am tempted to see what my milage is w/ it unplugged all together.

PS....been lurking since December...great site!
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Old 03-13-2009, 10:51 AM   #5 (permalink)
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Quote:
Originally Posted by turborich View Post
Maybe sb5walker will chime in on this.
Generally I only chime in when I think I can help. Kind of like the recent poster who "removed all the egr and emisions crap. what kinds of problems am i goin to run into? should i still plug in the three solinoids on the top of te valve cover even though the vacum lins are worthless?" I might be able to help the engine, (by re-hooking up the fuel pump vsv and a/c vsv, for starters) but can I help the poster? No.

People should understand that the 22re and 3vze are EFI engines. That is to say, a computer controls the injection of the fuel and the timing of the spark. They aren't WW II German aircraft engines, or early '70s British sports car engines, which have MECHANICAL fuel injection. In our engines, like it or not, understand them or not, they have COMPUTERIZED fuel injection. It may not be a very smart computer (it isn't) but it's what we have to work with. It actually does pretty well, provided that everything is right where it's expected and all the signals it receives are reliable.

If you pull the connector on the tps, the computer probably goes right into open loop mode, where signals from the O2 sensor are ignored and the computer uses default values for fuel and spark. 90 percent of the time, these values will be too rich or too lean (usually too rich), and the spark timing will usually be more retarded than is optimal. Perhaps with the tps gone the computer just uses vafm signals, but in that case the computer will not be adding extra fuel for acceleration, and when taking the foot off the pedal, the computer won't know to cut back on fuel. Then there's the IDLE signal, which is essential to a smooth idle and which is used for a bunch of other cases, including being able to read your codes.

The ONLY way for THESE motors to run properly, unless you convert them to 22Rs, is to make sure all the sensors that the computer needs (and the tps is surely one of them) are present and are working properly and are adjusted properly.

For the OP, to make sure the tps is working properly, you not only have to check the resistance values in the idle & full open throttle positions, as per the fsm, but you also have to check that VTA-E2 resistance changes smoothly as you slowly open the throttle, with no spikes or dropouts. It sounds like the sensor was failing this test.

For arek, there is a very tight tolerance for the right tps position: it is critical because of the IDLE SIGNAL. The correct procedure is in the fsm. If you don't have one, google 1993 toyota pickup service manual.

I'm sorry for the rant, but I guess I lose patience with folks who don't use the search function and don't read all the good information available in this forum. I get a little tired retyping the same thing again and again, but I'm willing to do it in cases where I'm confident I won't be wasting my time.
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Last edited by sb5walker; 03-13-2009 at 11:06 AM.
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Old 03-13-2009, 12:13 PM   #6 (permalink)
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I tried to do the TPS test via the FSM and got close. I'll try again. I am very aware of the 'tight' tolerance of the the TPS. I used to throw the EGR code but have not thrown a code in over a month. My idle is perfect. I figured an unconnected TPS couldn't be good and if anything would hurt gas mileage. Looks like I need to get the feel guages and meter back out.
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Old 03-13-2009, 03:54 PM   #7 (permalink)
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sb5walker :Generally I only chime in when I think I can help

I understand, sorry if I put you on the spot. You are the Toyota truck guru though.
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Old 03-13-2009, 06:09 PM   #8 (permalink)
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Quote:
Originally Posted by turborich View Post
I understand, sorry if I put you on the spot.)
-zorright. That was a rant waiting to happen, anyway.
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Old 03-14-2009, 01:00 AM   #9 (permalink)
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Pull the throttle body off and test the TPS.

go to www.4crawler.com Look up his tech section. He has a great way to test and adjust your tps. I had mine misajusted and it had the same issues. Deadspots in the throttle range....

Just need an ohm meter and feeler guages.
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Old 03-14-2009, 06:21 AM   #10 (permalink)
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Thanks for the replies guys. I really appreciate everyones time and knowledge. If I seem impatient, it's because I've had this issue since early Feb and a trip to toyota didn't fix it. After 2 days they replaced clean plugs with toyota plugs, and put on a used throttle body. This did not fix the problem, and the idle was set so high that once it got warmed up, the throttle would rise/ fall when i was on the brake at a stop sign (screwing in the idle screw solved this as per the archives). This precipitated the purchase of a manual, and I found the vafm tested poorly. I replaced it and still have the problem. The TPS does test out alright, I guess I have to test the harness, and the computer.
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Old 03-14-2009, 11:50 AM   #11 (permalink)
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I see your experience with the dealer paralleled mine - charged us a bunch of money to replace parts that didn't need replacing and the motor still had the problem. *sigh*

Like you, I gave up on the dealer and bought factory manuals and in the 13 years since I've done all the work myself. If you have the time and energy, it is a much better way to go.

You and your dealer have already covered the two most likely culprits for your mid-pedal range hesitation: tps/throttle body and vafm.

So, since apparently they were not the problem, here are a few other things to check (in no particular order):
  • O2 sensor - if it has over 90k miles, replace it.
  • Coil - specs for testing in the IGNITION - ON VEHICLE INSPECTION section of the fsm.
  • Crankshaft Position Signal - check the signal rotor clearance and signal generating coil resistance in the distributor. Same fsm section as the coil.
  • Dirty injectors - Get yourself a couple bottles of Red Line's SI-1 Complete Fuel System Cleaner - it is about the last product to have a significant quantity of Polyether Amine (PEA), the super-effective injector cleaning chemical invented by Chevron that Chevron's own Techron doesn't even contain anymore. Mix a bottle with 2/3 to 3/4 tank gas and run it down to 1/8 tank, then do the same with the other bottle.
  • Fuel Pressure - Could be a bad pressure regulator or damper - a test requires a specific sized banjo fitting to connect the pressure gauge - most of us have a shop run this, but Actron sells a cheap fuel pressure gauge - you just have to order the banjo fitting from them and I'm not exactly sure which one it is - I think it's the 8mm, but you should verify that if you want to get one.

I keep coming back to the tps, though. Did the dealer give you a new one of those, too? Or did they just transfer over your old one? If the latter, have you made absolutely sure that the E2-VTA resistance changes smoothly without any spikes or dropouts as you slowly open the throttle?

Anyway, good luck with it. If you keep at it, you will find the problem eventually. Please keep us posted.
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Last edited by sb5walker; 03-14-2009 at 11:52 AM.
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Old 03-15-2009, 07:03 PM   #12 (permalink)
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Test the wiring between the ECM and TPS. I have a bad wire and get a wandering idle and the inability to time the engine properly.
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