TBI surging idle

**PlayingWithTBI** · 07-09-2021

This .pdf may help, it shows how to set your min idle and then calibrate your TPS.

**C2500** · 07-10-2021

Explain how the IAC works.. I know it opens to allow idle but does it completely close with the throttle open wile driving? Will there be an issue with it with the counts that low? Dumb question I guess as I’m sure you have done it and it works..
Gotta give that I try..So if the TPS is above ? At idle where is it acceptable and think is should be at.50 volts…
Thanks

**PlayingWithTBI** · 07-10-2021

Originally Posted by C2500

Explain how the IAC works.. I know it opens to allow idle but does it completely close with the throttle open wile driving? Will there be an issue with it with the counts that low? Dumb question I guess as I’m sure you have done it and it works..
Gotta give that I try..So if the TPS is above ? At idle where is it acceptable and think is should be at.50 volts…
Thanks

When the engine is cold, the IAC opens to maintain RPMs until it warms up. Attached is an explanation from TunerPro RT on IAC vs CTS.

Once warm, as @Steveo suggested, you can play with the throttle blade to get IAC counts down to ~10. Looking at a couple logs mine runs ~15 at 650 RPM. When you accelerate the IAC opens up, sometimes over 150 counts. Then, if you let off the pedal and slow down, the IAC will close slowly until you reach targeted idle speed.

On my TPS, it's ~.45V which shows -1%. If the ECM/PCM sees a certain voltage above the threshold set in the calibration, it thinks you're no longer idling and have the pedal depressed so, AFAIK it doesn't look to control your idle.

Edit: the ECM may also cut off fuel when cranking thinking you're in a flooded condition.

**Turnshredder** · 07-11-2021

How do you have your stall saver set ? This can make it surge.

**C2500** · 07-17-2021

Stall saver??? I have set the IAC counts to 10ish hot in park and I adjusted the tps at .50volts. It’s better but still have its moments of surging sitting at a traffic light.. I did notice that the cruse in high (OD) with the RPM at about 1600 that surge is gone..
I cleared the ECM and going to give it a good drive to see if that helps as It did in the past..

It’s got a stroker 383 in it with a hyd roller cam and a 454 TBI unit on it…

**Turnshredder** · 07-21-2021

In Tuner Pro, XDF, 0D_TPV5_V250. "Stall Saver Activation Threshholds" These are Scalars you can mess with. These definetely caused mine to surge. my ADX is A217_0D_V250