IAC adjustment

[wheels87k5]

I have the info for setting the IAC and also the TPS voltage.

1. One thing that puzzles me is that it says to start the K5 with the jumper still in the ALDL, set the idle screw to a good rpm, then shut off K5, plug in IAC, remove jumper then start it up. It should be idling at the rpm you set it to. And it does. I set it at 750 rpm

I have also read that you remove the jumper in the ALDL before you start the motor.

When I tried it with jumper in vs jumper out it ran the same.

Does it really make a difference on the jumper? Can it damage the ECM by starting the motor with the jumper in the ALDL?

2. After setting the IAC and the TPS voltage it will idle where it was set at 750 rpm. But when you shut it off for about 2 minutes and start it back up, it idles at 1100 rpm. I take it for a drive, maybe 6 miles, and when I get back home and put it in park, it will idle at 750 rpm again. But, if you shut it off and start it again it will climb back to about 1100 rpm.

Wanting to figure out why it won't stay at 750 rpm idle when it's warmed up.

EGR/soleniod is taken out of the equation for now. All vacuum lines good. And idles smooth whether it's at 750 or 1100 rpm. No up and down. IAC is new.

 

[dyeager535]

Are you able to datalog?

I'm just wondering if perhaps there is something odd going on with the park/neutral switch. Should cause issues with starting, but the ECM controls high idle, and 1100RPm sounds about right for cold idle.

If it's idling at 1100RPM, and you drop it in drive, does it idle properly, or still try to rise to 1100RPM?

 

[wheels87k5]

Yes, I can datalog. And I'm getting ready to jump in and play with some VE tables. My son does this type of work on motorcycles, quads, etc and is going to guide me.

This blazer starts right up with no issues. I mean, it starts up better and idles smoother since I found and fixed a couple of small problems.

The idle drops from 1100 to about 800. Nothing bad. I just want to find out why it won't restart and idle at 750 like it's set for. I know it's going to be something very simple, but we'll find it.

 

[dyeager535]

Yes, I can datalog. And I'm getting ready to jump in and play with some VE tables. My son does this type of work on motorcycles, quads, etc and is going to guide me.

This blazer starts right up with no issues. I mean, it starts up better and idles smoother since I found and fixed a couple of small problems.

The idle drops from 1100 to about 800. Nothing bad. I just want to find out why it won't restart and idle at 750 like it's set for. I know it's going to be something very simple, but we'll find it.

Is it not programmed that way? I just don't mess around with TBI stuff, and it would seem odd to hold 1100RPM for a prolonged time on a restart, does it come down eventually without driver input, or will it hold 1100 until you change something like put it in gear, throttle, etc?

To be consistent like this, yes, you'd hope it would be easy to find!

 

[wheels87k5]

My goal for this blazer is to have it start up, warm up however it needs, to get to the 750 rpm idle. Just like it was brand new but better tuned. I know I can accomplish this. I finally got a better position at my work that will allow me to really get this thing tuned and running as best as it can.

I'm on vacation next week so I can spend more time on it, which means more questions. I really enjoying learning about mine and every one else's trucks. Just a fun hobby/lifestyle that makes me want to go out and see what this mini-monster will do. What can I say, I'm a 54 year old kid and hoping to make it to BB in 2017.

I'll do some more on it this Saturday and get an accurate answer on it holding 1100 rpm.