I got Ion from madz28.com to do a tune for me and was having trouble with my laptop connection but I ended up getting the tune loaded in, it was just that my computer connection was not good i guess. Had to take the desktop out to the garage... Everything is fine, but when I am driving around for a while, then come to a stop, my rpm's are getting really low and im losing oil pressure. Im assuming the oil pressure is because of the low idle. It is idling around 500 and really choppy. It was doing this before your tune also. Do you think this has to do with me swapping out throttle bodies to a 58mm. I was told the tps and or iac may be off. Do you know how I can fix that or what else may be the problem?

I checked the tps volts and everything was alright, it was at .72volts at idle and swept up to above 4 at WOT...

Where is the IAC located and how do I adjust that, do I need some sort of scanner? Or I heard you can clean up the iac...?

by the way here is another post of my same problem at fbody.com...
http://www.fbody.com/cgi-bin/lt1/read.cgi?msgid=244384

thanks for any help

 

oh and also, through Ion, the idle is set at 950, doesnt that mean it should idle at that rpm? Or will I still need to adjust the idle screw on my new Holley 58mm TB?

 

If he set it at 950 rpm, it should idle at 950rpm. Could be the IAC passages are plugged up, or the IAC motor isn't working. The IAC motor is in the bottom plate that you had to swap over to your Holley TB... its the part with the elctrical harness connector. Did you look at the passages in the bottom plate before you installed the plate? Is it possible you put some sealer on the plate or messed up the gasket when you installed it? Do you still have the coolant connected to the bottom plate? I saw one case where they didn't tighten the screws sll the way that hold the plate to the bottom of the TB, and coolant got into the idle air passages and made a real mess.

You can't adust the IAC motor. You can "reset" it.... Shoebox has the procedure on his website. You need to make sure its working. Best thing to do is put a scanner on it, and check the IAC counts, and observe how they are responding to the lower that programmed idle speed. If the counts are increasing, but the idle speed isn't, the IAC motor is not working or the passages are plugged up.

 

I dont have any coolant lines running to the IAC.. I believe the owner before me did the TB bypass. The openings are not plugged or anything, are they supposed to be plugged if you have the coolant lines taken off them? I just put the gasket on it that the new TB came with and I believe it was on there fine and fit good. I will check that also. What should I try to clean on the IAC?

 

You don't need caps on the coolant lines.... won't hurt anything leaving them open. But if you want to cover them for appearance its a 3/8" vacuum cap.

Check Items 41 and 42 on Shoebox's "How To" page.

http://shbox.com/1/how_tos.html

As far as how to clean the IAC motor, it unscrews from the side of the TB plate. There's an o-ring that you don't want to lose or damage. Spray only the pintle of the valve with throttle body cleaner. Do not allow liquid to flow into the electronics inside the body of the motor. Brush the pintle very lightly with something like a toothbrush to remove any deposits. Do not try to move or force the pintle in any way. When its dry, screw it back in, making sure the o-ring is in place.

 

ya know, when I swapped the TB, I found an O ring. I didnt know what it went to because it took me like 4 weeks to bore the intake for it so I went and put it in my tool box thank god. So do you think this could be my problem, the o ring is not on that?

 

Wellll.... a missing o-ring would probably let extra air into the IAC passages, raising the idle speed. If you didn't take the IAC motor out of the bottom plate of the throttle body (and there is no reason to do that), you shouldn't have found that o-ring loose.

 

i did take it off, i took all sensors off the TB and the plate also. I am going to check it and make sure it is the o ring for the iac...

 

Consider this... http://shbox.com/1/4th_gen_tech2.html#ICM_cooling

Mine idled the same way when it got hot. Try it out and let us know if it helped. Can't hurt, it's free.

Yes, you're going to need to set the base idle with that set screw in the TB. I have heard that can cause all sorts of messed up idling problems. I havn't been able to find out how to set it though.

 

You need to put a scanner on it. Back off on the throttle stop screw until the idle is at the specified RPM (650 in neutral for A4, 800 for M6, or whatever your programmer set it at for custom tunes). Then check the IAC counts. They should be in the range of 20-40 counts. Tweek the stop screw until you get the correct IAC counts. Then check the TPS voltage for closed throttle. Should be in the range of 0.20-0.90V. Most people prefer to get it in the 0.50-0.70V range. You may need to slot the holes on the TPS sensor so it can be rotated to adjust the voltage.

 

yea ive gotta find someone with a scanner i can borrow because this is driving me crazy! I put the O ring back on and cleaned the iac like you said and of course its doing the same thing...

It is only doing this when i actually drive. I can sit in neutral and rev and hold the rpms at 3k for a while and it will go right back down to the normal idle. Yet if I go and actually drive the car and come to a stop, it drops way down and even dies...