TPS adjustment (Page 1/1)
sledcaddie JAN 02, 11:31 AM
85 SE with 2.8 V6 & 4 speed: Already replaced a bad IAC because it was idling about 3,000 rpms. Now it idles about 950.

The TPS spec at idle is "less than 1 volt". I've read on here that the "sweet spot" is between 0.5-0.6 volts. Mine reads 0.74 volts. If I "oval" the holes out, to adjust the TPS, will the idle come down a little, if I get the reading to the "sweet spot"? I've read that the TPS is very touchy.
fierosound JAN 02, 12:12 PM
See Factory Service Manual.
TPS should be less than 1.25 volts at idle and 4.5 volts with throttle wide open.
If you are getting those readings and idle is 950 rpm everything is fine.

You are chasing a problem that isn't there.

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[This message has been edited by fierosound (edited 01-02-2020).]

Blacktree JAN 02, 01:24 PM
I consider 0.5-0.6 Volts to be the "sweet spot" for the TPS at idle, because it practically guarantees at least 4.5 Volts at wide-open throttle. But it's not absolutely necessary. If it's below 1.0 Volts at idle, and above 4.5 at wide-open throttle, you're good.

Another very important thing is TPS consistency at idle. When you let the throttle snap back to idle, it should drop to the same voltage every time (or at least within a very small margin). If the idle voltage varies, it will confuse the ECM and cause surging / stalling. A dirty throttle body or weak throttle return spring can do that. Doesn't sound like you have this problem, but I'm putting it out there just in case.
sledcaddie JAN 03, 10:38 AM
Thanks for all your input. The only reason I questioned this is because, early on, it seems like the idle was usually around 800 rpms. What are others' idle speeds?
olejoedad JAN 03, 12:17 PM
800 is fine for.an automatic, 950 for a manual to s perfect.