Hi guys, I'm running a fairly choppy hydraulic cam with a MAF TPI setup and a roughed in eprom. The commanded idle speed is 750 rpms. The car gets pretty close most of the time, but hunts slightly. Until I have the equipment to burn a chip, so I can decrease the IAC counts, would setting the minimum air such that the engine, warm, is idling just under the commanded idle speed (say 700 rpms), make the IAC less prone to raising and lowering the idle? I think that the stock motors had a 450 rpm minimum air setting, so the IAC was playing a bigger role in setting the idle speed.

Another question: What if I had the minimum air setting too high, so the engine was running at 900 rpms idling on its own. Obviously, the IAC can't close anymore than being already shut. Will the computer do anything to try to bring the idle speed back down, ie back off timing, or will it just let it idle higher than its spec'd.

Thanks so much

 

I would say yes to both of the main questions. Don't know if I'd set the minimum idle as high as 900 rpm. A little higher then the 750 desired might be a good place to start (say 800 RPM).

IIRC the MAF setups don't use idle control SA so no problem with a lot of timing being pulled. The ECM will just close the IAC and be done with it.

It is important to reset the TPS to 0.54 volts. Do this after the minimum idle speed has been set.

If you haven't been set up with a scanner/data logger there is the free Moates logger. Runs fon a PC/laptop.

RBob.

 

With or without data logging, though, as I understand it, it makes sense to set the min idle to about 100 rpm lower than the target in the computer, right?