I started my 7.3 up this morning and the ambient temp was around 40 degrees. I clicked the chip on the high idle setting (DP Chip) and went inside to grab my coffee. BUT, the sound coming from the exhaust sounded like an animal crawled up there and was restricting the flow. It was LOUD! Was this the AIH doing its job?

 

Yes, the truck sounds constipated and such or like a boot over the tailpipe. Its doin its job

 

the Air Intake Heater is on the intake side of the engine, and it's just a coil that heats up and heats the air as it goes by. the sound you were hearing (espcially if you have an opened-up exhaust), was the backpressure valve (EBPV) closing to restrict flow so it would let the engine warm up faster by keeping the heat contained.

 

That's what I thought it was. It does have the 4" exhaust and this is the first cool morning I have started it since the install.

The sound reminded me of the air sucking in my carb on my 390 without the air cleaner on....

 

Just to futher what Strokin was saying, that's part of the Cold Ambient Package (CAP), referred to as the Engine Warmup Device by International. The PCM activates it, raising the rpm and partially closing the EBPV, based on IAT (intake air temp) and EOT (engine oil temp). Your truck was just doing its job, helping it get warmed up.

I'm not sure how cold it gets in Montana (I think it gets pretty darn cold, though), but the coldest temp I've started my PSD at is about 10* F, and that's w/ the straight pipe... it was shrieking like a banshee, or a jet, haha. Colder it is, the higher the RPM raises and the more the EBPV closes, and hence the louder that shrieking gets. So... just wait till winter.

 

Winter temps reach -30F in my neck of the woods. The truck will be parked in the heated garage by then, but I can't wait to hear what noises it'll make!