TPS Voltage! Opinions on where to set it too.

bx4525 · Post by **bx4525** » Mon Dec 19, 2005 9:55 am

I have a '93 GT supercharged w/ 42 lb. injectors, 255 intank walbro, 80mm pro-m mass air, stock block w/ e-cam, GT-40X heads. 1.6 rockers and a custom tune chip. Everyone has a different opinion on where to set the TPS whether its .92-.95 or .97-.99. I know there will be no performance gains but I also like a smooth idle and the best setting for my car. I hear often to stay below .95 because the eec richens up any higher than that. Any opinions guys?

mach1 · Post by **mach1** » Mon Dec 19, 2005 4:10 pm

I dont think there should be much of a diff between .98/99 and .95. I would set it around .95 to allow for heat or any thing else that may make it go over 1V. If you set it at .99 and things expand a bit it may push it over 1V, etc.

fireguy50 · Post by **fireguy50** » Tue Dec 20, 2005 2:23 am

0.85 is best.

JuiceSC · Post by **JuiceSC** » Tue Dec 20, 2005 9:10 am

I set mine to .95v. I've had it as low as .91 and as high as .99 and have not seen any noticable difference. But above a certain value (1 or more) the eec doesn't like.

incon_331_twinturbos · Post by **incon_331_twinturbos** » Wed Dec 21, 2005 12:49 am

fireguy50 wrote:0.85 is best.

could you elaborate? I was just wondering, as I don't know first hand and it is lower than the other values which I have heard to set it to....

TIA.

Brad

fireguy50 · Post by **fireguy50** » Wed Dec 21, 2005 1:24 am

As long as it passes the self-tests, between 0.60-1.00 at closed throttle.

there is no perfect setting, it will react the same if it's set between 0.65-0.95 at closed throttle.

So I split the difference mid 0.80's

runner · Post by **runner** » Sun Dec 25, 2005 12:19 am

To expand more about setting the TPS:

All 5.0 EEC-IV's use the "turn-on" voltage of the TPS as a base voltage - consider this voltage "Relative Zero". The EEC-IV's+ have diagnostics to make sure that the sensors "make sense". For the TPS, those voltages are roughly 0.6v and 1.1v at start-up, and ~4.9v max.

But, you can not just set the TPS voltage near a limit and expect everything to be okay. The EEC supplies the +5V to the sensors. That voltage can vary by ~2.5%. Also, all resisters have some sort of temperature coefficient. That means that the resistance changes with temperature. Also, you have the contraction/expansion of the TB-tab going into the TPS. Also, you have expansion/contraction of the TPS body. Also, you have the uncertainty of the EEC A/D convertor (Approx equal to a few counts). Also... well, you get the point. :)

Those are just some of the factors that go into a proper analysis of a sensor and it's "meaning".

For stock OEM TB and TPS, it "should be" plug-and-play. But, change the idle setting, use a non-Ford TB, and you must to check the TPS idle voltage and you may have to elongate the TPS mounting holes.

Thankfully, the TPS is not a "super" critical sensor (like the MAF and the O2's are). The "main" use, IMHO, of the TPS is rate of change to "estimate" the proper injector pulse width for the desired A/F. The O2 sensors and MAF are "very slow". Probst gives a basic explanation and insight into the how the EEC-IV uses those sensors.

So... what about the urban legend of setting the TPS to ~0.95V?? That's easy. :) Many people adjust the idle screw and/or change the TB. Many aftermarket TB's "may" not allow a plug-and-play with the TPS. There are a "few" low-quality 5.0 parts suppliers that supply, IMHO, junk with very low quality and very loose "specs".

So, once again, if you use a non-Ford TB, or adjust the idle screw, you must check the TPS idle voltage. But, for a "100% stock" parts that meet all of the Ford Specs, the (Ford) TPS "should be" plug-and-play.

incon_331_twinturbos · Post by **incon_331_twinturbos** » Sun Dec 25, 2005 12:31 am

runner

fireguy50

Thanks, I get it now...

TPS Voltage! Opinions on where to set it too.

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