Holley Commander multi port throttle body injected 540 stalls when temp hits 160, which is the thermostat temp. Ive got a couple thoughts but was hoping someone with more knowledge might be able to give me more direction.

Is it the older commander 950? Are you running closed loop?

well... in any efi system, when the motor reaches operating temp it goes to closed loop and leans the mixture out. on good efi the fuel table is a gentle curve starting at full rich when dead cold and then gradually leaning until it get full warm but yours might be different and go " all in" at once , so to speak..

i have absolutely no experience with your system but somewhere in the calibrations it has to give you the ability to define this curve both for fuel and for idle speed etc and your job will be to make sure that the values you choose for full warm are those that will sustain your idle and low speed transistion.

and this is all assuming the rest of the basic mechanicals are correct like no vacuum leaks and the throttle plate is set correctly etc...

I believe it is. Year 2000 Innovation/Volvo motors MPI throttle body on single plane intake.

Cold starts fine and runs until operating temps and then you can hear the IAC open and it starts sucking for air and dies. Restarts and stalls immed.. Once it cools down, same process.

Spiking temp sensor?

Have you opened the electrical box and confirmed it's a Holley ecm? I would have thought Innovation would use the original MEFI controller. Either way it won't be a closed loop system. Generally when a coolant temp sensor fails it defaults to -40ish and you run really rich, it sounds like you're starving for fuel. After it dies, you could try disconnecting the CTS and firing it again. It should run really rich like the choke's on. The best solution to avoid replacing parts at random is get someone with a scanner to plug in and watch it happen. It could be the fuel pump, a sensor, ignition module, etc.. If it really is an old commander box, you can download the software for free and buy the communication cable for a few bucks.

Thanks Haxby. It is a Mefi controller. I am trying to get access to a scanner. I agree, I think it is starving for fuel which is why I thought it might/may be a spiking temp control sensor causing it try and lean out to much, but now that I am saying it, if it is the temp sensor, it is happening when it gets hit with colder AF/coolant when the thermostat opens. hmmm?

Closed cooling by the way with the thermostat housing as part of the heat exchanger.

There is a ECT multiplier in the MEFIs and perhaps the multiplier is zeroed out at 160. In other words things are fine until the 160 mark is reached and the ECT multiplier goes to zero, which would zero out the injector BPW and kill the motor.

Seems to me that the IAC should be open until it warms up, then the hissing sound should go away. That's the way my 600's run. Try calling the guys at Innovation: (941) 355-7852.

Thanks Chuck. I hear you. I am a little baffled. Never a hiccup with these motors before though so I cant complain.

Used the old paper clip/led test and got no codes so I am thinking it is the IAC, although based on my limited knowledge, not sure why it happens at 160 degrees? All other sensors would show a code, no?

By the way, did speak with Scott Yow and he said historically speaking, he would lean to the IAC.