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Discussion Starter #1
Would someone run a test for me. It has to be on a 1st gen - with 5sp - someone who is not currently having any engine jerking problems at lower RPM.

This is the test: Disconnect the TPS (pull the connector off), and drive your car for several minutes through 1st to 4th gears. You don't need to exceed 3500 RPM. Just some stop-and-go driving.

Post any anomolies you notice e.g., Idle differences - jerking - surging, etc.

Thanks - ahead of time.
 

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I'll go try this right now
 

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pak- i don't know what this test was for. and I was actually really amazed by what happened. I figured there would be a lot of problems, but it ran good. The idle was at maybe 1000 RPM, which actually I just reset my Idle screw, so I'll tell you whether or not that is different than normal for my car prbly tomorrow after i drive it for a while. I felt no hesitation, no surging. In fact I would almost venture to say that my car ran better. Call me crazy, but I kinda liked it more with out the TPS plugged in. After I found that everything was normal, I was in second gear and hammered it around 3K RPM, and it seemed like it took the car less time to react and build boost. When I let off the throttle after giving it quite a bit, it seemed like it reacted to that fast too. Maybe my car is weird, but I noticed that when letting off the throttle, it was super quite, then after I switched gears, and gave it more gas, once again it seemed to build boost faster. I could have been running slightly rich, but I'm not sure. Does it hurt to run the car like this, because if not, I'm gonna check it out some more. Maybe I'll run a tank of gas through it to see if I'm consuming any extra gas.

What was the point of me trying this anyway. I do have a 91 VR4.

I'm also interested in what people think should have happened.
 

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dragon -

Perhaps your TPS has been adjusted incorrectly, and no signal (limp home mode) results in better performance than the incorrect signal.

Adjustment procedure:

http://moojohn.com/tpsinstructions.gif
 

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this could easily hold true.
 

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Discussion Starter #6
Well, that's different than what I expected. I'm still tracking down my engine jerking problem at lower RPM. I noticed the other day, that I can sometimes find the perfect spot on the throttle position that runs fine - when I moved the throttle just slightly, it would begin jerking. So I'm thinking that there's probably only one sensor on the car that can detect a change in throttle that small - the TPS. So I pulled the connector off - the car jerks alot - put it back on - it stops (or at least goes back to intermittent). So now I'm thinking that either the TPS is bad or I have a bad connection.

So I thought a good test would be to have someone else check it out. EDACS reported on the board a while back that the TPS had solved a jerking problem for him.

The manual claims that the TPS doesn't have alot do do with how the car runs. Which your test results seem to confirm. It does on mine however. I need to think about this some more. Something's still missing in the puzzle.
 

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Today I adjusted the TPS wrong. At around 3k rpms the engine will hold its speed just fine, accelerating is fine, but below 3k rpms, holding it steady, the engine would cut out and coast as if I was giving it no throttle, when i was actually giving it throttle to hold it steady. Once I gave it enough throttle, then it decided to jump big time, and decelerating to instant hard acceleration gives a nice big jerk. If you haven't already, turn your tps fully clockwise and see if that helps. On mine, my mechanic turned way counterclockwise, and he turned it too far. Thats why it started doing the above. I assume you've already rebuilt your ECU, but that still sounds like your problem to me. Have you tried disconnecting the TPS to see if the automatic settings make you car run better? I will think this over this weekend, see if I can think of anything that might be causing this.
 

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The whole idea is to turn the TPS until the closed idle switch <i>just</i> registers closed at idle. Any more either way and you're throwing off the calibration.
 
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