MSefi.com read only forum (Jan.15,2018)

Im using an Edelbrock Throttle Body with GM Stepper IAC. The strepper extends and retracts as required, but will not seat it the bore even when extended at 255. Above 255 the motor dosent extend any more. I used a little ball of modelers clay to see if the pintle actually seats, it wont. I know its not a motor problem because i originally had the stepper motor wired wrong and launched the pintle off its screw drive (can get lots of movement out of the motor). Im guessing, but it appears as though the Throttle Body IAC bore is drilled too deep not letting the pintle seat in the bore. Of course im going on the assumption that the pintle has to seat in the bore in order for me to get the mechanical throttle valve adjustment set. Any help will be appreciated.

ROCKET455 wrote:Of course im going on the assumption that the pintle has to seat in the bore in order for me to get the mechanical throttle valve adjustment set.

This is correct.
Contact Edelbrock and see if that p/n works in their TB.

The stepper motor came with the throttle body from edelbrock. In doing some more research, it appears that the max steps (255) can be extended further. I believe i can edit 2.890 ini line 230 (IAC min steps 1 - 255) to say 1 - 300. Is this all i need to do?

It's worth a shot. Have you unscrewed it far enough to seal without power applied to it?

Thanks for the replys. When i had it wired backwards, i litterly shot it off the threads. It will travel far enough to seal if i can get it to move past 255 steps, Im hopeing editing the ini will allow me to move it further than 255!

Yes you should be able to edit the ini file to get more steps. In theory you could get 32 or 65K steps.

I am having the same problem were 255 will not close my air off completly. From setting my IAC start to 20 and IAC cranking to 1, it takes about 20 resets to retract the pintle from closed to fully open. I did edit line 230 in notepad to read 1-400 steps, but it still wont go past 255 steps extended. Is there something I missed in the ini file? Using MSII 2.890 code, GM stepper motor. Any help on this would fix my starting issues I ope.

The 2.890 ini file that I have, which should be the same as the official one, has 4000 steps as the max for the IAC steps (but only 500 for the table steps - which should, and will be changed to 4000 to be consistent), But either way, it should have gone over 255 without having to modify anything. So I suspect the wrong ini file may be in use. The file that is actually used by MT is negasquirtII.ini and has to be in the correct directory. When you update an ini you have to copy the update ini, which will have a code version suffix, into negasquirtII.ini.

Any update on this?

I'm having the same issue. My stepper will shoot out way further than required when wired backwards, but when wired correctly, will only go out 100 steps, which is not near enough to seat.

My ini seems to be as needed

There are 2 primary inputs that affect the no. steps: the IACstart steps which has to be enough to fully retract the motor, no matter where it is at startup. Once it is fully retracted, it should go to where the table of steps vs clt temp tells it to go. Does the IAC gauge go over 100 steps ? If it doesn't then there is something wrong with the configuration. If it does, then that means it sent out more than 100 step pulses so the motor should move this amount. If it doesn't then either it is not wired right, it is missing steps, or it is of an unusual type that does not respong the way the vast majority of IAC motors respond.

I have not heard of a motor moving further if it is wired incorrectly. The 4 separate pulses have to be in a certain order and if they are not, it can only slow things down, not speed them up. Can you wire it "incorrectly" and only give it a few steps and get it to go where you want it ?

That was really weird. It did the exact same thing with two different standard GM IAC's. No matter what was displayed on the screen, the pintel would always stop at 100. After searching through the ini files (and not finding or changing anything!), I tried it again, and now it's working perfectly!?! I can't imagine opening the ini's could have done anything, but I struggled with it for MANY tries with both IAC's with no luck, and now all of a sudden it works fine.

Thanks

Hey Rocket455,

Any update of this? I have the same throttle body and am curious how you ended up seting up your IAC.