OK, been doing a ton of reading and need some guidance. When I start truck and warm it up....look at scanner to check for closed loop...and look at IAC's it stays at 145. Now from what I've read this can be either a perameter set wrong in my tables or a timing issue....how can I tell? I do have one more question on same subject, I do not have a park/neutral switch hooked up to ecm nor do I have the auto/manual wire hooked to ecm either....could this cause the Iac to stay at 145....maybe?

 

Ops , forgot I am using a 4288 / AOmask. Just looked at my tunerpro IAC park position and it is set to 145...this is for when truck is shut off, and the IAC goes to the wide open position, correct?

 

Depending on the descriptions, it can mean "in Park" position (not the parked position), if it's a table (not just a single number). That would be the base position for the IAC at those temperatures in park/nuetral, with no accessories.

There's also a shutdown position (or homed position, or something along those lines) which would be for the position the IAC goes to at key off (after it bashes its head shut for a little bit).

 

Before you do anything, make sure the min idle speed is set correctly.

What is the idle speed?.
Does the IAC reset after driving?. There typically is a VSS reset speed.

Yes, you want to have the P/N switch operating, as it changes the commanded idle speed. You can get by without it, but, you may wind up chasing the things around, to get a devent compromise.....

 

Redngold it is a single number so I should have said the number was in the constants table, sorry.

Grumpy I'm glad you you replied because one the post's I read was when you and dimented were discussing this.

I went back and looked for the min idle speed but I'm not sure where / what it is? Could you tell me how to find this? I'm using tunerpro rt if that helps.

As far as the IAC resetting, how can I tell this also? When I was looking at it today and scanner in hand I did look at the IAC pintle on the TBI when it was running and turned off and it/pintle never really seemed to move. I did get it to move when I adjusted the fuel / air screw but not like it should...it only went down a count or two plus it meesed with my TPS setting ....but I had to see.

Now with the P/N switch, would you just ground this and keep it where the ecm see's it to be in P/N all the time? I have read where some say to ground it and others say just leave it unpinned at ecm. Last with the VSS is there anyway I can make it look to the RPM for this? My truck never came with VSS so I'm limited here. Thanks in advance for any info.