: Ideal IAT Sensor Conditions

06-18-10, 09:24 PM
Alright, it has been a while since I did my 'mod' on my '99 Eldorado. The intake is currently run out in front of the radiator (behind the front fascia). Let it be known that I do NOT mean to resurrect the old 'CAI' debate as I will agree that the stock one is adequate and one cannot simply throw a cone on.

I am not pulling any codes at the moment. However, I am going to rework the intake so it pulls air from cooler side of the car (driver side).

My question regards the IAT sensor and its involvement in setting off a particular code that I struggled with for a while: P0101

Is the IAT sensor (which originally resides in the airbox) involved setting this code? Does a (big) difference between the ambient temp and the IAT cause the code to set? Further, would an air current moving over the sensor cause false readings?

Basically, I'm just curious as to what the ideal conditions are for the IAT sensor so that I may avoid the problem of P0101 and its inherent stalls when I rework the thing. Again, I honestly think that I had a stroke of dumb luck in not having the code set at this point.

Thanks everyone...


I think that I somehow just got lucky with how I plac

06-18-10, 09:52 PM
P101 is a MAF code. IAT codes are P110-114. The IAT or IAT codes codes should not affect the MAF cause a MAF code, if that is what you are asking.

06-18-10, 10:05 PM
The reason I figured it would be associated with the MAF codes is because when I still had the cone under the hood and the IAT sensor plugged in, I would invariably pull P101 and eventually have stalling issues. However, if I unplugged the IAT sensor (the ambient temperature sensor is substituted for the IAT), I would have absolutely no problem with the car, aside from pulling P0113/P0111 (due to the sensor being disconnected).

It seems odd to me is all.

06-18-10, 10:14 PM
Hmm, seems awful suspicious, but I would not think the two are related. That said, it would not be the first time I was wrong.

06-18-10, 10:23 PM
Could the IAT sensor somehow help govern how much air passes goes into the engine due to temperature variance? If so, then when I could see how the MAF sensor would be getting innaccurate readings if the IAT sensor were getting innaccurate readings.

06-18-10, 10:27 PM
Could the IAT sensor somehow help govern how much air passes goes into the engine due to temperature variance? If so, then when I could see how the MAF sensor would be getting innaccurate readings if the IAT sensor were getting innaccurate readings.
No. It simply tells the PCM the intake air temperature so that it can control the injector pulses accordingly (somewhat like a choke).

The throttle plate governs how much air passes goes into the engine. The MAF sensor measures it.

06-18-10, 10:33 PM
That makes sense. Hmm.... What else could it be then? I mean, I'm glad I don't have the issue any more, but I don't feel very fulfilled because I didn't truly solve the issue.

06-18-10, 11:00 PM
BTSOM :noidea: I feel your frustration though.

06-19-10, 12:54 AM
Well, I'm going to be breaking it down this weekend, so we'll see what happens. Going to be cleaning off the TB, as well.

Submariner or anyone else, if you are out there, do you have anything to suggest? And Ranger, as always, I appreciate your assistance!

06-19-10, 08:07 AM
Many times a code test won't run if another particular code is set.
Perhaps the IAT code has to run and pass before the MAF code can run? That might explain why you didn't see the P0101.
I can't offer much advise on what you are doing there, just wanted to chime in about the code.

06-19-10, 10:05 AM
OP, I'm assuming that your IAT is separate from the MAF body, unlike mine which is IN the MAF bore.

The absolute best place for a "remote" IAT sensor would be in the intake duct about a foot or so before the TB - that way the sensor reacts to the underhood heating and cooling of the intake air as temps change due to road speed, traffic, and idle conditions. (Yes, the IAT goes in the intake airstream - turbulence won't affect it - it's highly damped.)

Even with your remote air intake pickup point and my airbox mod in which most of the air comes from out in the fender there is quite a variation in intake air temp. On the highway, cruisin' at 70, IAT is about 5 to 9 degrees above ambient (the sensor on the hood latch brace), but near suburban IAT goes to 15 over ambient, and I have seen it in DC crawl traffic at 140*+ ! - but, get on the road and down it goes - it's all due to airflow and underhood temps.

www.scangauge.com --- you can set up any 4 of 12 gauges, one of them being IAT. Interesting to watch, as are ignition advance and MAP (vacuum).

06-19-10, 10:27 AM
Thanks for that, Submariner. I had actually wondered how much hotter the air got.

Ewill3rd, I had thought that might be the case, however, when reading the troubleshooting for P0101 code on Alldata, it says if these codes are also set (P0113- the IAT sensor one), to fix those first, which leads me to assume that 0101 is not dependent on 0113. Could be wrong here.

Could a 3 in. piping have been the cause of the issue? the stock duct was 4 in. and I have an adapter for a 4 to a 3 in pipe. Could that have had something to do with it? On the other hand, why doesn't cause a problem now?

07-08-10, 03:26 PM
Just a bit of an update...

The other day I was driving my car to Autozone to pick up the parts to do the (hopefully) final rebuild on my remote intake. Suddenly I felt the infamous lurch and my Check Engine light came on, popping the P0101 code.

Well, I've finished the thing now- shortened the tube, deleted the accordion piping, and added a 4 inch 90 bend coming right off the MAF housing (was a 3 inch diameter). I've been driving it since with absolutely no issue.

I really think the initial reduction in the pipe size was the culprit of the problem. I'll probably post some pictures of the whole car once I clean up the engine bay some...

And, again, I'll say that modding your stock CAI with a cone filter, unless you go all out with it, is doing absolutely nothing for your car! Don't give in to 'Honda complex' with the N*!!

Again, thanks for the wealth of information and advice you guys continually provide.