Everywhere you look for TPS voltage will tell you idle voltage- I've experimented with different WOT voltages- can't tell the difference- my TPS can be adjusted anywhere from 4.1 to 5.1 volts @ WOT- with idle still at .54. Since max voltage is increasing, so is the rate at which the voltage is climbing. I heard that 'Vettes ECM's are set for 4.5 volts @ WOT (when it goes into open loop). I've also heard 4.2. Anybody have a clue? Do they differ?Since the ECM gets alot of info and changes it according to TPS position, what is the best WOT voltage? Also, I've seen TPS voltage enhancers..only offered for 'Vette TPI (any difference?). Anybody notice any improvement? Appreciate all your input.

 

There is no specified WOT TPS voltage in the service manual, only what it is supposed to be at idle. I would think that the rate of increase from having the WOT set at 4.15vdc to 5.0vdc would be so minimal that wouldnt make a performance difference, it would only leave you susceptible to either codes 21, 33, or 34.

As for the "enhancers", don't throw your money away.

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Kevin Irving
85 Trans Am WS-6, 305 TPI, custom burned '86 PROM with '87 "165"ECM, Accel Supercoil & 8.8 Wires, MSD 6AL, Aluminum Driveshaft, TB Coolant Bypass, Ported Plenum, Modified MAF, Syclone Fuel Pump, JET Airfoil

15.556 @ 86.65mph, Nov 10, 2000.... I know it sucks.. but it will get better!

http://www.geocities.com/transam85tpi/

 

I know there is no specified WOT TPS voltages, but I'm just wondering if anybody knows of the best voltage to set it at. I have noticed small differences in fuel economy and power, but since it took awhile for the computer to learn the new voltages it's hard to tell. I heard the CPU goes into open loop at a predetermined voltage (TP angle). Supposedly, at 95 percent or more TP angle, the TPS is supposed to send voltage signal to the computer high enough that the computer recognizes it and ignores O2 sensor input for trimming air/fuel ratio. Without knowing that voltage I can't set it right. I'm not sure of the accuracy of this information, just posting it for hope that someone knows what's going on. If this is true, then shouldn't there be some benefit in having WOT TPS voltage set correctly? That is, after all, a close to a 20% difference( 4.1 volts/ 5.0+ volts). I believe on LT1's TPS sensors are unadjustable, but us TPI guys can probably benefit if there's any truth to this (maybe a sales gimick for TPS enhancers?)

 

I had my car on a rearwheel dyno a couple of weeks ago and was surprised by the effects of tuning with the t.p. sensor. Im using an A.S.@M 54mm t.b. wich uses a larger dia. cam than the stock peice. The larger cam was setting a code at W.O.T. for excess tps voltage wich in turn leaned the A/F ratio out to 17/1. After setting the base voltage to .47 the A/F ratio came down and the motor picked 30+ H.P. at every interval above 5000rpm. I didnt have time to experiment but it is obvious that the volt. at W.O.T. has an effect on the A/F ratio.

 

Hrm, you may wish to also try this on the PROM board as it also has to do with our eproms. Many of those guys have experimented and readjusted such things many of times with recordings and may be able to give you the answer your looking for. Just a thought.

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89 IROC-Z 350 TPI

-Flowmaster Catback
-Performance Resource Chip
-700R4 (Rebuilt) Too much done to actually list
-K&N Airfilters
-Ported Plenum
-2.77 Gears (not much to brag about but eh, its there)
-MSD 8.5 mm plug wires
-Problems every other day with the car (probably not a mod, but to me it sure makes a difference)

 

Actually, the ECM enters a power enrichment mode at 80% of WOT, or on a stock TPI, about 4.0VDC from the TPS. There is no real benefit of increasing the voltage beyond that level, since the ECM mode doesn't change and the enrichment factors don't change with additional throttle angle.

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Later,
Vader
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"No matter how hard you try you can't stop us now..."

 

So if 80% of WOT is supposed to be 4.0 volts for power enrichment, it hould be about 5 at WOT, right? Or do I use that 4 volts as a reference for tuning when I want power enrichment to activate? Or both? Starting to see the light now...

 

Actually, the ecm goes into PE sooner than 4.00 Volts AND the percentage of TPS for PE is completely changeable within the eprom. The eprom is the best place to modify this not the TPS.

The only voltage to worry about on the TPS is for idle; if you want PE to occur sooner, then I would do it inside the eprom.

What I WOULD look at is how wide the blades open at WOT. Some people have found the blades in the TB do not fully open @ WOT, which will reduce air flow.

But forget about adjusting the TPS voltage if you are already getting over 4 volts. Trust me, the ecm already THINKS you are at 100%. Adjusting for 4.5 volts is a lot of work for nothing. This trick goes back to the early days when people didn't know as much about the eprom as we know today.