IAT Sensor?

What symptoms would a failed IAT sensor give?

(assuming I have the right name here, sensor inside the air filter box)

Depends how it fails, I guess. I'm going to guess it'll fail cold, which means you will pick up 5-40 horsepower* because that's the same as an eBay "power chip" Or, more likely, the car would run rich.

OBD-II car? Borrow a scanner that displays real-time data and see what it's reading.

*results not typical

Well, I'm troubleshooting a warm-hot start issue in the 96 Aurora.

while it's not huge deal (car gets driven to work, parked 9 hours, driven home) it is annoying and not right.

makes making small trips impossible....

Car never overheats, idles perfect, drives perfect. will not restart when warm or hot.

Originally it would start when hot (up to 10 minutes after car shutoff, now no go)

I'm gonna say Not the IAT. Engine temp (Coolant), maybe, but that's a big maybe too. When it won't start, is there spark? If you squirt some combustible fluid down the intake, will it try to start?

Otherwise, given the brand involved, I'm thinking Gas Cap Trick here.

ECT has been changed before..... Always has spark, always has fuel.

Tried starter fluid before, basically backfired through the throttle body and had a flash fire.

Gas Cap trick? what? undo it?

I'd say your timing was off. I'd look at the timing pickup wherever it is on that motor. Dizzy, flywheel, whatever.

Gas Cap Trick: Unscrew the gas cap, roll a new (used) Toyota underneath, screw the gas cap back on. Sometimes you need a new gas cap too.

It's an OBD-II car. I love real-time readers. Plug it in and look for the oddball reading.

Dr. Hess wrote: Gas Cap Trick: Unscrew the gas cap, roll a new (used) Toyota underneath, screw the gas cap back on. Sometimes you need a new gas cap too.

True, True.....I'd like to replace it with something with a 6-8' bed that has 4wd and holds 5-6 people

Keith wrote: It's an OBD-II car. I love real-time readers. Plug it in and look for the oddball reading.

Anyone in West Michigan have one I can borrow?

The IAT and the coolant sensors take the place of a choke on a carb.for cold weather starting.

given the symptoms...... what about a Camshaft postition sensor?

Mileage is right were it should be @ ~20mpg
Engine Temp stays at about 200 while driving, 240 sitting Idle's perfect Power is all there

just won't restart after warmed up.

Grtechguy wrote: given the symptoms...... what about a Camshaft postition sensor?

Doode,

I SAID: I'd say your timing was off. I'd look at the timing pickup wherever it is on that motor. Dizzy, flywheel, whatever.

Wouldn't timing affect cold starts?

Lemme try again: To me, in my non-automotive-professional opinion and based on decades of wrenchin' on stuff, it sounds like your car's Electronic Fuel Injection Computer is not receiving the proper timing signal, that is, the signal the motor provides to the computer to tell the compter where the motor is in it's 2 revolution, 4 stroke cycle, when your motor is hot. So, the timing is off/corrupt. Look at whatever that motor uses for timing pickups: cam angle, distributor, flywheel, harmonic balancer, squirrel, troll, whatever. One of the pickups is likely acting up when it's hot. You could put a heat gun or hair drier on it or them and see if you can duplicate the failure when it's cold.

OK.... sorry to have such a thick german skull....but i was born with it.

I'll look into figuring out the timing.

If the engine runs ok warm, how does timing enter into the equation ? The IAT will affect cold starts and maybe warm.

weird update....drove the car from one office to another.....started right up no hesitation 10 minutes later after being shut off.....

The only thing I've done, is put a new thermostat in and coolant topoff.

lol....OK...I still haven't fixed the issue with this damn car

problem progressed into random slow speed stalls when at operating temperature. I found the MAF to be bad (disconnected and was able to drive the car) but the stalls have been getting progressively worse.

Today, I drove home with the idle air valve disconnected. perfect... no stalls. only issue? my idle went up to 2000rpm.

confused....I really want to ditch this car and go back to a beatup old TBI truck. but that's not in the cards while having a family and wife that's recently decided to go back to school full time.

So, any more thoughts on this odd ball issue? does the MAF ($250 part) control the Idle Air Valve and could that be my issue? or could it be the throttle position sensor? I'm really starting to hate modern cars

I seem to remember Cartalk giving a crank angle sensor as the link to these type symptoms on GM's.

SupraWes wrote: I seem to remember Cartalk giving a crank angle sensor as the link to these type symptoms on GM's.

replaced and the cam sensor as well

The IACV does work in concert with the MAF. If the MAF is bad it needs to be replaced since that is the major sensor in the intake system. IACV's frequently get "gummed up" especially if the MAF is not working properly.

1. Pull IACV and clean thoroughly. They are not as sensitive to work on as the MAF
2. Replace the MAF

Dr Hess may be on the right track. I had an Escort doing the same thing and it was the ignition module. It would start after Ilet it cool for a while. Weird thing it never affected the running.

The IAC controls the idle speed, I don't see that as being relevent to the starting problem, esp warm.

Hal wrote: The IACV does work in concert with the MAF. If the MAF is bad it needs to be replaced since that is the major sensor in the intake system. IACV's frequently get "gummed up" especially if the MAF is not working properly. 1. Pull IACV and clean thoroughly. They are not as sensitive to work on as the MAF 2. Replace the MAF

Well....Replaced the MAF with a junkyard unit and soaked the IACV pretty thoroughly last night. All the driving I've done since has been the 15 miles to work. BUT....probably jinxing myself.....idle is smooth now and not stumbling, no stalls, and restarted hot...

I can't believe an air meter was causing all these problems....but if so... shrugs....

You can buy a can of MAF spray cleaner at Advance. I have a couple GM vehicles, owned several with the MAF unit. Give it a quick spray at every oil change, especially if you have a K&N and/or de screen the MAF. I had a Bonneville that would run rough and hard start hot. A big bug had stuck and died right smack dab on the MAF sensor. Cleaned it and good as new.