CobraStangGT16

Yo guys, it seems like my car is going from one problem to another after rollin 100k!

This time it's a CEL (check engine light), and I have no clue why it would go off. I will get it checked tomorrow, but I want toknowif my 2 ideas are credible.I have 2 scenarios as to why it might have threw a code...here they are. Please tell me if either one may be a possibility as to why it threw the code.

Senario #1: This morning, I was heading to a Cobra car show, and I wanted my car to sound a little more rev-happy. I did the IAC mod again, I've taken it off, and put it on twice this week, just to experiment why I have such a high idle (1200rpm). I did the IAC gasket mod this morning and about 6 hours later, after stopping at a light of a freeway exit, I see the reflection of the light on the windshield. Could the IAC throw a code?

Scenario #2: Coming home tonight, I was VERY low on gas. Mylow fuellight was on, and the gauge read clearlybelow the empty line. I pumped gas before my car died, which would have been only minutes later. I only filled 6 gallons, and headed home. I did a normal fill up procedure. I have heard that a gas cap can throw a code? Is that true? Did me filling gas at a very low tank throw a code?

Thanks guy!

oxfordgt

Who knows what caused it. Just get it scaned tomorrow and let us know the code.

CobraStangGT16

TTT

I'll get it read this afternoon.

^iLLuSiOn^

yea could be anything, a scanner will tell you exactly what it was and yes the iac can throw a code

CobraStangGT16

*UPDATE*

Ok guys...heres the deal. I was right when I thought the IAC threw the code. I had it checked at Autozone and the code was: P1056---Idler Air Control/Auxillary Control.

So so biggy. I know the problem is, and I know why it happened. But how come this doesn't happen to others who do this mod? The only reason it threw the code was because the smaller IAC hole I did in the mod made my idle at 1200rpm, thus, the computer reads that the IAC is not doing it's job correctly, and the light comes on.

So how can I keep the mod (I really like it, it really makes the car sound like it should, not hanging rpm's and it makes my exhuast 'pop'), without having a high idle, and a CEL come on? Help me out here, I wanna figure this out. I'm going to a roadcourse, and I think it would be cool to have that IAC mod while at the track.

yourmom6990

maybe make the hole a little bigger?

CobraStangGT16

I did that, and it made things worse! When the hole was only 3/16"s it worked fine, idling at a perfect 800 rpm, until I started it when the car was cold, and it would not keep an idle. It would just die. So I made it bigger, and now this happens.

yourmom6990

do you have an aftermarket throttle body, or plenum?

Sniper6677

Both the IAC and the gas cap can throw check engine codes...make sure your IAC is indeed working properly before fiddling with anything....after all you may need a simple replacement

CobraStangGT16

I highly doubt I need to replace the IAC, because when I put the stock gasket on it, it works perfectly how it should. But I hate the "rpm hang" on the stock IAC gasket. It drives me nuts! The new one is much better, and it gives a great "engine braking" effect. It helps alot when in traffic, and on the track.

And no aftermarket t/b or plenum. In fact, it's still the 1999 plasitc plenum which was recalled because people cracked them!