TPS problems (Got 2 sensors, same problem)

[cygnus58]

So if i adjust it per spec, i should expect some difference in idle for the first 3 start/stop cycles?
It does need adjusted, I only had like .54 volts at idle position. 11% of 4.89 read.

 

[langer1]

No the idle is set by the IAC and the computer, not your TPS.

 

[Scorpio18]

After I seafoamed my Jeep, the idle improved alot!!

 

[Ecomike]

So if i adjust it per spec, i should expect some difference in idle for the first 3 start/stop cycles?
It does need adjusted, I only had like .54 volts at idle position. 11% of 4.89 read.

Langer1 is partly right. The IAC tries (1) to control the idle air flow rate and it is controlled by the computer (ECU), but the ECU uses TPS sensor data to decide what the idle speed should be. A TPS Idle stop setting of say 1.00 volts will cause the computer to adjust the IAC to run the idle up to something like 2000 rpm on a Renix.

Also contrary to some other postings here, Renix does seem to store and use some limited prior operating sensor data that causes a new TPS idle setting adjustment (with everything else working correctly) to make it idle weird for the first three restarts before the ECU replaces the old TPS operating range data in its memory buffer with the new settings. After 3 restarts it settles down to a consistant idle if everything else is working correctly, meaning no vac leaks, no problems with fuel, spark timimg, O2 sensor, grounds.....etc.

(1) Keep in mind that vacuum leaks and ground wire losses (even small ones) can screw with the idle speed too! The vacuum leaks is a direct effect, the ground wire losses affect the ECUs measurement of the true TPS setting.

 

[ren]

Sooo, how does the stupid thing manage to run with the TPS not even hooked up? The reason that I ask is that we now have another $300 Lardeo, and the pigtail for the TPS has been CUT OFF on the engine side of the harness. Yet, it will start up almost as quickly as a "fully functioning" engine. Yes, the idle is skecthy, so the TPS is going to be re connected. I can't figure out why it was done this way to start with though.

 

[langer1]

The computer just uses best guess, the engine runs, but not well.

 

[ren]

Sorry, I got the PS's confused for a minute here (Too many things that end in "s" {tps, cps, pos, ....}). I meant the CPS. Somebody had chopped the engine side harness connector off and it still runs.

 

[Ecomike]

Sorry, I got the PS's confused for a minute here (Too many things that end in "s" {tps, cps, pos, ....}). I meant the CPS. Somebody had chopped the engine side harness connector off and it still runs.

It will start and run with out the TPS, O2, CTS attached. Sometimes it will start with out the IAT sensor working properly.

It can't start with out the CPS attached and working.

 

[ren]

Figured out what was up. Someone has run a new set of wires right from the comp down to the tranny. wierd.