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4.0 OHV Absolute Throttle Position

239

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I’ve read threads on this site about the tps and it seems that 19.6% is the normal position for the TPS at idle. Mine has recently started dropping to 19.2% at times and I’m getting erratic rpms lately, like a 30-50 rpm change every second. The truck runs really smooth and the rpms stay steady while the throttle is open, however.

I’d appreciate any input on this. I have a new Motorcraft tps but haven’t installed it since I rounded the bolts on the original and I’m not looking forward to destroying the old tps to remove the bolts. I’ll also be testing it with a multimeter this weekend. Thanks.
 
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fast_dave

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Answering this as I'm going out the door with the wife for more Christmas shopping - so sorry for the short answer.

Look for previous posts regarding the installation of a new TPS and twisting the TPS body while it's bolted to the intake man so so as to obtain a specific voltage "sweet spot" that is read with a standard hand-held voltage meter.

This sweet spot voltage has a ;lot to do with your idle and off the line/throttle tip in performance.

You'll probably have to look years back for this info BUT it's well documented.

If nobody has chimed in by tonite, I'll try and take a look for you.

HTH - FD
 
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974X4BLACKSPORT

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Mine does exactly the same thing.
 
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239

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I’m not looking to adjust it as I prefer stock design. I’ll most likely get a throttle body at the junk yard and rebuild it, and then install my new tps. I just want to find one that hasn’t been tampered with when it comes to the idle adjustment screw.

I unplugged my IAC with the truck in park and it dropped to 400 rpms and almost stalled. From what I’ve read it should only drop to 500. So I suspect that too.
 
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fast_dave

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239,

No prob - just trying to help a fellow brother not throw money at a problem ;-)

The dial it it in "mod" I suggested doesn't cost anything, and in my case worked for me when I replaced my factory FORD TPS with a Standard Motor Products TPS (at a 1/4 of the cost) over 13 years ago.

The TPS is essentially a rheostat, different rehostats have different tolerances, and the dialing-it-in to a sweet spot with some "pre-voltage" cured my ECU condition with the rolling idle and throttle response/tip in.

If memory serves me correctly, I had to elongate/widen one of the screw holes with a drill bit just a smidge to dial in the sweet spot voltage and it worked for me.

Check it out - before throwing money at your problem you could always install your new TPS and measure the voltage your getting with it in the "stock/unmodified" position.

Then, you could dial it in, and if you feel that you haven't got any benefit of hotting the sweet spot, simply dial it back to the unmodified voltage you started with - no harm done.

HTH, Good Luck & Merry Christmas!
 
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239

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Thanks for the input. Merry Christmas.
 
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