colonboy14

iTrader: (7)

Well, I have been having some idling and low speed drivability problems, so I checked the TPS voltage and it was only going from .65 - 3.8 volts. (This was having it adjusted as far down as I could get it) I ordered a new TPS, and this one does the same thing! What could be going on?

vernw

iTrader: (2)

Follow the procedure to set the minimum air in the tech articles and see if that won't allow you to adjust it down a bit more (and buy you more room on the top to go over 4.0v).

Just a thought, but what readings can you get out of it with it not attached to the TB? And is the TB opening all the way at the 3.8v reading?

colonboy14

iTrader: (7)

It'll go up to 4.3 volts not attached, and yes it is opening all the way. In my service manual, it says that anything below .96 V will be set as 0% throttle, up to 4.6 V at WOT.

Is there any way to tell if the computer is recognizing WOT, like by the diagnostic light flashing while driving in diagnostic mode, for example?

vernw

iTrader: (2)

Then I'd do the min air procedure and see if you can set the TPS adjustment far enough to get over 4V.

I don't know how to read % TPS without a data logging program like TunerPro or DataMaster (I use both)

racecam

CHECK YOUR IDLE CONTROL MOTOR. IT MAY BE STICKING AND CAUSING YOU THE PROBLEM.

vernw

iTrader: (2)

As for the IAC - be forewarned, the steps shown in a data log are NOT a report of where the IAC actually is, they are only where the ECM told it to go to.

I had a bad IAC that wasn't really moving even though the data logs were showing movement. Took a while to figure that one out and swap it out.

CrazyHawaiian

You'd have to use a scantool to find out what TPS voltages the ECM is getting back. If it has the proper voltage ranges off the car on a test bench, then its gotta be something on the TB. You could reset the stock IAC and clean it, I recently had to replace mine. I think the correct pintle measurement is 1.108 inches or 28 mm from tip to flange. Install it, then get in the car and tap the gas, car on for 5 seconds, off for 10 seconds, then back on. Unless someone has jacked with the minimum idle before, I dont see a need to adjust it. I didnt have to adjust mine and I replaced both TPS and IAC (this is on an 89 L98).