Voltage To TPS

[qhatherly]

Havn't been able to find an answer searching so i thought i'd just ask.

A little backround: redtop, jwt ecu, 550's, cobra maf, gt30r, stumbling idle, occasional misfire, hard cold start (but thats b/c of bad fpr).

My problem started when i measured the output voltage from tps->ecu it was .1ish closed and .6ish at WOT, and it wasn't getting much higher when i tried adjusting it. So i replaced the tps and of course the problem continued. The tps was only getting .6 volts from the ecu (power to tps). Checked resistance on hot and ground side of the sensor and everything checked out and tried another ecu and got the same readings. What should the ecu->tps voltage be and why would it be low like this? Seing as its late right now think simple, b/c i probably overlooked something stupid.

[Slidin240Wayz]

The range is from .35~.65 Set it at .5 when idle, right smack in the middle.

Carlos

[qhatherly]

the problem isn't setting the closed throttle tps voltage, it's that when i open the throttle completely it barely makes it past 1 volt, and i'm asuming (but not sure) that the tps is powered by a 5 volt source, or at least something higher than the .6 it is getting from the ecu at the moment.

i should mention that i measured the connector aswell as the ecu pin, both came out the same so it isn't a short. and when i checked the groundside of the tps connector (multimeter on connector pin and bat -ve) i only got 1 ohm or so of resistance so the ground is good aswell.

[Slidin240Wayz]

try .5, see if that works

[Tomslide50]

The ecu supplies the tps with 5volts. So your saying that you changed both the ecu and the tps, so they can't be the problem, and you have verified that both power and ground don't have high resistance? Unplug your tps and check for continuity between the 5v(supposed to be 5v anyway) reference and ground in the harness. Any continuity? Now check the 5v feed wire to signal wire. Any there? and finally check the signal wire for continuity to ground. You shouldn't see continuity on any of those. If you do, then you have a short in your wiring. Post your results.

[qhatherly]

just checked all three on the harness going to the tps, no continuity

[qhatherly]

from ecu harness to tps connector the 5v feed had .2ohms resistance and ground from tps harness to battery ground there was .8ohms

[qhatherly]

j/w, does the ecu ground through the mounting bracket?

[Tomslide50]

The ecu does not ground through the mounting bracket.

I don't see what the problem could be. The only other thing I can think of is that the ecu isn't getting a full 12v to begin with, so that when it reduces it it gets really low. I don't know what ecu pin the ecu gets power though, so the easiest way is to unplug the knock sensor harness(don't know where it is on SR but it's probably close to the tps like on the KA) or any other sensor that sees 12v from the ecu. Does it have 12v? If it's not then you'll know that the ecu isn't getting 12v itself. If it's 12v then I'm completely out of suggestions. If not then you have a high resistance on your power feed to the ecu. Since you tested the ground pin on your tps harness to the battery neg for resistance you've verified that the ecu has good ground because it goes through the ecu. After this I'm out. lol. Good luck!

[qhatherly]

lol thanks a ton for the help, i'll give the knock sensor a try tonite

[SoSideways]

Originally Posted by Slidin240Wayz

try .5, see if that works

.5v makes the idle rich, and makes the car run a little more rich and less peppy.

Try putting your closed throttle at like 0.38v closed throttle, and WOT voltage to around 4.05v to 4.07v. You'll find that your car's a lot more peppy when it's off boost and your gas mileage should improve as well.