How can I adjust my idling, without interferring with the voltage at the TPS? I got the voltage right on, but it won't idle. Runs great out on the road. But stalls at stops. I know I can turn the idle screw, to make it idle, but it will change the voltage. The TPS, is adjusted as low as it will go! WHAT CAN BE DONE NOW?
darn... its been so long i have forgotten the IAC voltages to shoot for at a training session about 20 years ago.. .here is how i handle it...clean throttle body bore... i usually remove it to clean it.. and I always hold it TPS UP so no spray goes into the throttle position sensor by flowing thru the shaft bore.. i also just wipe the bore with a shop towel sprayed with cheep brake cleaner.. i pay attention to the throttle blade also.. but mostly to the edges... this takes only a few minutes... i also do this without removing the throttle body.. just use care to not swamp the TPS sensor. then put it back together... start the engine and warm it up to full operating temp..you will probably have to raise the idle speed slightly with the screw... then unplug the idle air control motor.. so it closes completely now... adjust the idle stop screw so the engine is just barely idling... this is headlights off.. AC off.. plug the idle air control back in... take the engine rpms up to about 2000 RPMs with your hand on the throttle lever.. hold the speed steady for 10 or 15 seconds.. then ever so slowly.. back off on the throttle.. this gives the computer the ability to modulate the idle air control to learn the new settings..there are some TPS sensors that have a small amount of adjustment...sticking volt meter probes into the idle air control connector with it plugged in.. and the engine running will give you the ability to change the TPS setting.. to get the proper idle speed and idle air control percentage.. but i don't recall what that IAC voltage should be.. the guy doing the training turned his head away when he said the voltage and i could not read his lips. i thought it would be in the info they gave us but it was not.. if you have some other EEC4 or EEC5 cars around.. measure the IAC voltage warmed up and idling.. that will give you the range to look for.. shhhh!!!... don't tell anybody.. but i have a chain saw file that i use to change the opening shapes on TPS sensors.. if you get into OBD2 or GM cars and trucks.. usually with Throttle body injection.. look at the TPS BASE voltage... operate the throttle a few times... each time the TPS needs to return to the EXACT SAME fraction of a volt.. what happens is the throttle shaft bore wears... since the stop is like the ford.. on the end of the lever.. the tiny change in angle as the throttle shaft comes to a stop in slightly different positions. this changes the angle and the TPS voltage..this totally confuses the computer and keeps the program from switching into idle fuel trim..want to have some fun.. do you have a digital volt meter that reads MS... milli seconds.???next time at the junk yard.. visit the imported section.. look at volvos and saabs.. some models use the same shape connector as the fuel injector connectors on the anti lock brakes and the distributers.. both sides... of the connector... this allows you to buy both sides... use something like a female insulated bullet connector to crimp the wires to make an extension or break out connection... so you can monitor the injector pulse width..1.2 to 1.4 MS at idle is expected.. on EEC4.. you only need to monitor one injector.. please use care to NOT short either of these to ground.. you can buy this injector break out harness.. but they are about 40 bucks last time i bought one.. do a similar break out harness for your oxygen sensor.. so you can easily monitor the oxygen sensor with your volt meter or with a 35 buck air fuel ratio gauge.. you should run a KOEO and a KOER test... and if everything is working properly... you will get a PASS 11... this will restore full engine power to the EEC4 system..
I think 4.99 v is what you want to shoot for.
My bad. It is .96-.99 volts.