Hey Guys,

Put the scanner on and my TPS is reading .56 at idle and 3.70 at WOT. I just read in the tech section that it should be over 4 volts at WOT so is my TPS bad?

Thanks

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Ed Stevens
88Roc350TPI
1988 Camaro IROC-Z
350 TPI
700R4
T-Tops
"1KILLRZ"

 

Yea I would say to replace your TPS and set it again. That is what 2 of my friends are doing they had the same problem as you do.

 

Ok, so we know that 3.70 is not enough.....but, what problems does this cause since it's not getting enough voltage? My cat is hollowed out and the car smells wicked rich sometimes, especially when I'm flooring it to pass cars, etc. People say it stinks bad when they follow me.
Could this be a result of the TPS not sending the right voltage to the ECM?
Thanks

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Ed Stevens
88Roc350TPI
1988 Camaro IROC-Z
350 TPI
700R4
T-Tops
"1KILLRZ"

 

You probably are not getting enough volatge for the ECM to see WOT (about 80?%) to get into the power enrichment settings in the EPROM.

But before you replace the TP, look at the voltage again while opening the throttle from under the hood...if just trying to press the gas pedal, you may be bottoming out on the floormat, or carpet, etc...or the throttle cable could be stretched, not allowing you to get the TB to WOT.

 

Also, make sure you have 5 volts going into the TPS as well.

 

The TPS can be made to move in four directions, up/down and fore/aft.

Try moving the TPS fore and aft. This can cause the WOT voltage to change and exceed 4 volts.

Loosen both bolts, adjust the fore and aft movement of the TPS to give you over 4 volts. 4.35 is a good starting point.

Tighten the lower bolt a little, then move the TPS up or down to set the base (closed throttle) setting.

Tighten the top bolt, then the bottom.

Recheck both settings to make sure the settings didn't change during the bolt tightening process.

Hope this helps.

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

 

I agree, sounds like it just needs to be adjusted so that it reads over 4V at WOT.

Cant say why its running rich... any mods?

 

If your hitting the 100%, meaning that the ecm is seeing the 3.xx volts as 100% throttle, you will be fine. Only way to know that is to have a scanner(ie. Diacom or compareable).

Brendan

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1987 IROC-Z L98,SuperRam,EB 6085's,LPE 219/219 Roller, Crane 1.6RR, EB TPI Base, 58mm TB, ADS 24#, AFPR, K&N, EB TES, Catco Cat, 3" Borla Cat-Back, Accel cap,rotor,distro/other crap, MSD 6AL, MSD Blaster 3, Aluminum DS, 94 Disk Rear, Adjustable Valve, Precision 3.73 Gears, Sub-Frame Connectors, Hotchkis Lower Control Arms, KYB Shocks/Struts, Suspension Techniques Lowering Springs, Polyurethan Bushings all over the place, Moog Upper/Lower Ball joints and Tie Rods ends/Idler Arm,

To see the ROC, Check out the webpage Here

 

madmax and Jake are correct, I'd assumed you had already tried adjusting it.

 

Brendan (leirch) is correct about how the ecm interprets it...if the ecm sees 100% TPS (regardless of the voltage) or acutally more like 60-70% TPS, depending how the PE vs %TPS is defined, you ARE in WOT.

WOT (PE) is completely controlled by the eprom. You set the eprom to whatever %TPS you want PE to kick in. The ecm does not care about the TPS voltage...just the %TPS. If you have a scan tool as Brendan suggests and measure the %TPS and getting readings above 80%, you are going into WOT. Your BLM/INTs will change to 128/128 as verification.

FYI, if you measure the TPS with the engine off, you will get a lower TPS voltage reading. You need the engine to be running to properly measure it. I get less than 4.00 volts if I hook my car to a scan tool and push down on the throttle. But if my engine is running, the WOT voltage goes to 4.28 volts. (And PE kicks in around 3.5 volts...based on the way I have it kick in, in the eprom). I can change it to occur whenever I want.

Adjusting the TPS sensor is not a valid way to control PE; the eprom is.