Contour Enthusiasts Group Archives Forums Modifications Zetec Performance P1506 Idle Air Control Over Speed Error.

threw a CEL on tuesday when I was coming home from the track and that is what the OBD II code is...
brad???? could this have something to do with the TB?

Wasn't that the code that D Davis was throwing right after he put his TB on? I find it weird since mine hasn't thrown a code.

I think it was.... can't remember off hand.... and he was off to dyno his car by the time I knew what the code was

I wonder if there is a fix to this or is this a TB problem?

I'm hoping brad can shed some light on this tomorrow.. or when ever he gets online next...

That is the same code DDavis had with that TB. It must be something to do with the idle bypass port being "to" optimized and getting to much air. Since there isn't an idle bypass port adjuster screw on those TB's like there is on the SE and SVT ones, we've got to slow that idle air down some other way. Perhaps by filling it in a bit, filling the tiny hole in the throttle plate, or ??? I'll work with you on it until it stops throwing the code... If all else fails, I'll optimize your core, PC it red, and send it off to you with a slightly less open idle port.

BTW, not quite the same problem DDavis had since when he had the TB it wasn't fully closing the throttle plate. A slight adjustment of the throttle plate and it was ready to go on Joe's car.

This is the same "error" I had, but I'm not certain that it's the exact same code. Anyway, mine seemed to be related to the plate not closing fully, as Brad said. If I forced it closed, the idle would drop (but I'm not sure the code would've cleared that way).

If I were you, I'd try to force the plate closed further via the throttle cable linkage. Don't break it, but if you turn it towards the cabin (I think) and the idle settles down, it's possible the spring may have came loose and lost a wind or two.

Good luck to you both. I think that particular TB is cursed

well I cleared the code lastnight and have put about 60miles on the car since and no CEL yet... the cars idle is a little funky... it will goto 800 and then after a while it will jump to 1200 and slowly drop to about 1000 or a little under.
I gotta work tonight at the pizza join delivering so I know I will get a few miles on the car and we'll see if I pop another CEL..... well actually it's and O/D off light

MWAAAAHAAAAHAAAHAAAAHAAAAAA

It was all a part of my elaborate plan to take you out of the quickest-Zetec running. Thanks for helping Brad, your $20 is on the way