my tps reads 4.37v? as i open the throttle the lowers(4.37,4.36,4.35 all the way down to about .90?

 

i believe the MAF TPS sensor should read .54V closed throttle and should go up over 4.5V at WOT

 

TPS should read below 1 volt when closed and go up to just under 5 volts at wide open throttle

 

mine is reading 4.xx at closed throttle and .xx at WOT?

 

why is my SH*T reading backwards?

 

does it run like crap? If at all? I bet it runs pig rich. disconnect your tps and check for the proper voltages at the connector itslef. Don't recall them off the top of my head, but you should have a 5 volt reference with the key on engine off, and a ground and a sensor wire.

 

the TPS should read 0.54V (+/-0.065V) and on WOT around 4.5V..
This is on TPI MAF cars..

 

You are reading between power and signal (incorrect) not signal and ground (correct).

Stick one lead on the engine block/head and take readings on all three wires, write down the position and the volts. One wire will read 12 Volts all the time, another will read ground (low milivolts), and the middle will read low (.5 Volts) at closed throttle and high (4.5 Volts) at WOT (do this with key on, engine off).

 

You are supposed to measure the voltage between terminals A and C, (I think).

 

dam, i was probing the wrong terminals .got it straight i went to adjust the iac and i cant get it down to 500rpm without it dying?

 

I think that you are confused. You can not adjust the IAC. You adjust the throotle blade angle and the TPS, not the IAC. The IAC will open or close to keep your engine running at the RPM that is called for in the EPROM chip.

And dont feel bad about the engine stalling at 500RPM, my engine would stall there also, I would simply set the throotle blade so that the RPM to about 650 to 700RPM. Then you ajust the TPS to about 0.6V. Then the IAC will react and keep the engine at the RPM that is being dictated by the ECM.

 

theres a great article on the homepage ,go to technicle articles, scroll down to how to adjust iac and tps follow the procedure youll be fine, later jimmy

 

still tryed that procedure

 

You have to use a handheld, diagnostic tachometer. The thing in the dash filling the hole next to the speedometer is NOT a tachometer. It's more of an indication of whether the engine is running, maybe. If it reads 1,000 RPM, the engine might be doing 800-850. Some are even worse.

Also, the TB minimum air position has to be done with the engine at normal operating temperature, transmission in DRIVE, and IAC fully closed and disconnected.

 

i have a auto meter tach and a manual trans?

 

vader is saying the tachs are notorious for being off, usually a little high.you have an autometer so it doesnt matter.

 

i paid good money for my tach thinking it was accurate? how could i get one in there that is accurate?

 

autometers are accurate, our stock in dash ones arent. later jimmy

 

BTW the IAC program can be changed /reset, this is at a programing level achieved by very few in these parts. When a real change (not just a sensor data input) to the IAC programing is made. It will affect all kinds of things, because the IAC programing PID loops are used all the time not just at idle.

Watch the change in IAC counts, as the engine is driven under different conditions. They jump all over the place, as intended by its (IAC) engineered purpose.

It is the #1 reason a motor doesn't stall or high idle (rpm trim). Think of it as the throttle man on a deep sea racing boat, whose job it is to keep the rpms within a certain place/range by following very specific rules (the IAC program). Or a type of cruise control for engine rpms, not car mph.

At idle if you have a vacuum leak (more air or less fuel, then expected) then the IAC counts will be lower/smaller and if there is more fuel (excessive fuel or less air, then expected) higher/bigger counts and the rpm will be higher.

If the TB stop, IAC pintle length, rpm relationship is changed from OEM specifications (IAC closed/extended 1 1/8" and engine at 450 rpm), then there will be interesting results.

This is a big cat (IAC) and mouse (sensor input) game for the computer to play, while trying to maintain a "steady rpm/idle".

I have seen times when the IAC counts float around and the engine RPM is steady. The only time the rpms will move around is when the limits of adjustment are reached (max limits or the ramping factor). If the IAC program can no longer compensate for the "issue", this usually is seen as, a hunting rpm (motor boating, roller coaster) type of floating up and down, as the IAC program acts like "a dog chasing its tail"

 

With a manual (in neutral, obviously) try to set the minimum air to 625-650 RPM, then let the IAC have its way with it.

I'd still recommend using a diagnostic tach, just to be sure.