Initial Setup of TBI, TPI and MPFI systems. Min Air Adjust, TPS set and Fuel Pressure

[EagleMark]

I must have lost my post? I was going to check this when the kids IH TBI 16197427 Conversion is done.

When doing it this way you may have to turn engine off, wait a minute and restart to see actual results as it resets during start. If you make changes while running and IAC hooked up. Bigger throttle opening = less IAC counts.

Then have to check TPS voltage. Although some say it's OK under 1 volt, I like factory spec per ECM/PCM.

[1project2many]

Here's a homegrown way to set minimum air that I learned with carbs and still works today. Get a strip of paper about 1/4" to 3/8" wide and maybe 5" or more long. Open the throttle and insert the paper into the throttle bore past the throttle plate and shaft. The paper should be perpindicular to the throttle shaft. Release the throttle and gently try to pull the paper. If the paper has a slight drag then the throttle angle is ok. If it's too tight you risk stalling and a sticking closed throttle when the engine's cold. If it's too loose you risk having a high idle the ecm is unable to control. Ensure IAC counts are 30-35 and tps volts are below .75 and you're usually good to go.

If you want to set minimum air while the engine is running there are a few ways to do it. You can remove TPS or use a substitute TPS to fool the ecm into thinking the throttle is closed, then increase engine speed slowly until the ecm / pcm tries to command the IAC all the way closed. Disconnect IAC, close the throttle, and check your RPM. Or you can get an IAC test tool and use it to drive the IAC closed. Or you can get a special rubber plug designed to plug the IAC passage (known as a dog turd to GM dealership techs).

[JeepsAndGuns]

Or you can get an IAC test tool and use it to drive the IAC closed.

I have often wondered if there was a way to "bench" test a IAC. Any more info on this tool? Is it electrical or what?

[EagleMark]

I have often wondered if there was a way to "bench" test a IAC. Any more info on this tool? Is it electrical or what?

I've done that on my test bench, the plunger extends all the way and pops out!

[JeepsAndGuns]

So basicly 12 volts has to be "pulsed" to either extend or retract it? Like grounding one wire, then quickly touching and releaseing the other to a hot wire?
I have a couple spare ones from a old dodge tb, I may play with them, if I burn it up there is no loss...lol

[EagleMark]

My test bench is not running, I'm in the middle of building a harness or I would check for you. Pretty sure 12 volts will burn it up. It's a 5 volt signal... IIRC

[JeepsAndGuns]

Ahh, good to know.