ive read the tech article on how to adjuct the iac tps. one ? that i have is that when u set the tps u must back the idle screw off so that the trottle is closed, which isn't stated in the aricle but it says it in my haynes manual . would u ajust the tps then iac then. in the tech article i make it sound like u ajust the iac then tps but wouldnt it be the other way around. does anybody know whats going on here. is there a amount of volts the idle screw should be adding to the closed postion?

 

Your TPS is not adjustable, like MAF ones, and doesn't need it, (assuming you still are using the '730ECM)...you can do as the TA says to reset the IAC.

What's your problem anyways?

 

i think i have a different ecm because it will run in closed loop if the tps isnt set right. i just want to set the idle screw were it should be. it idles at 475 in drive warmed up. 2 years ago i was running .60 and the idle screw closed and ran better than i can get it to run now. i just reset it to .60 and put a new iac motor in and want to correctly set the minium air entering the motor at idle or is that controlled by the ecm reguardless of the idle screw.i doesnt run as bad as it did but i just want to see if i can get it were it will run as best as it will.

 

Yes, .60 for tps is perfect, this is where it will run best. Actual spec is .54 +/-.074 . But always make sure your tps is set with your engine warm! this does make a difference.

No, the tps setting assumes your min. idle is set correct. Do not set tps with idle screw turned back. As long as your close first get your min. air/idle set up properly. Than come back to the tps and make final adjustment. Min. air/idle is extremely important to proper engine operation. Once it is set you should never adjust it again even after changing iac. Setting a new iac is simple but once the idle screw has been messed with it gets a little more complicated.......Here you go. Follow this and it will work every time, if it doesn't you have problems elsewhere.

IAC Min. Air adjustment

To properly adjust engine must be warm (this is very important)

* Short pins A & B at diagnostics connector under steering wheel.

* Turn ignition on but don't start (you will now hear your iac valve clicking) wait 45 sec. This time is needed to insure the valve has fully seated into min. idle.

* Now disconnect the iac valve

* Now pull your short off the terminal

* Now start the engine

* Now disconnect the electronic timing advance wire (brown wire passenger side engine compartment firewall ***single wire***)

NOTE: your motor is now ideling with no computer interference, if it shuts off you need to hold throttle open until screw is up far enough to keep it running.

* Now adjust the idle screw until you get to 450 rpm

* Shut down motor

* Reconnect IAC and Timing wire.

* Restart motor, clear any left over codes

Your now setup properly. You should idle at 600 rpm on a warm engine while in drive with foot on brake

idle screw should never need adjusted again. Your ecm uses this adjustment as a basis for calculations, so move it and engine can't operate properly.

Hope this helps, I know it works on 86 thru 89 (tpi)

 

ok i did what u said when i tryied startingwith iac disconnected whould stay running till cranked the idle screw. got it to run steady at 500 in park and about 350 in drive. if i crank too much on the screw the motor would start surging. do i need to set to to 450 in park or drive. i noticed i big different when fired back up. alot quiter and smoother barely if tell its running. but im not acheiving 600 in dive with the foot on the brake. sould my engine be surging when setting the min air.

 

All settings should be done on a warm engine and in park. When you hook your timing advance wire back up, your motor should be ideling at around 850rpm in park and 600 rpm in drive with your foot on the brake. It is very important that all steps are done in order. if one is skipped you must start over from the beginning again.

No your motor shouldn't be surging. Make sure your timing is correct. With the timing advance wire unhooked you should be at 6 deg. But check your tag under the hood for your correct deg.

Try again. Print out theinstructions and take your time. If there is anything in the instructions you don't understand let me know.

If you have followed everything correctly and your timing is correct but your motor still isn't runnung wright than you have something else wrong. Try setting it up again before anything else, but first make sure your timing is correct. (very, very important.....unhook your timing advance wire b4 setting your timing)


Good Luck.....

 

i had my timing set by the dealear earlier in the summer because i thought it was off. set a 6 deg. i asked about the idle and the mechiniac said it was at 475 and it was within factory specs. with all this considered what do u think about setting it to as smooth sounds as i can get it? back to the surging at 600 rpm when adjusting it. do i have a vacuum leak? ithink im going to try giving up on getting it to idle at 600 hundred in drive with foot on brake. its weird because when im almost stopped it will idle at 6oo but after stopping it shortly droppes to 500 or 475.

 

Strange, doesn't sound like a vac leak. If you had a vac leak you would be idling high. It still sounds like a setup issue to me. Do you have access to any diagnostics equipment? If you do, let me know what you have and we'll see what kind of trouble shooting we can cook up.

 

what could happen if you set the tps with the engine cold, i set mine at .60 while the engine was cold, didnt no it made a difference, will this hurt anything?

 

No, it won't hurt anything except coarsen the ECM resolution, but that will will be minor, nothing you will notice. If you want to change the TPS minimum, you must do the Minimum Air Rate first.

 

Setting the tps on a cold motor won't "hurt" anything. But as your motor reaches normal operating temperatures your tps will no longer be at .60 . You will probably be out of spec on the warm motor, I have seen this b4 set on a cold motor @ .60 and warm it was at .64. You TPS is plastic and it's electronic. Resistance values change on electronics as they warm up. For this and other reasons all adjustments on the motor should be done at normal operating temperature (if you want it to be perfect).