Check Engine when no Throttle

[Macv]

I keep thinking this has been answered before but I can't find it. I've searched everything from "Check Engine Throttle" to "Coast Engine Light."

Anyhow, driving at a slower speed ~40mph, (though it may happen at other speeds, I only noticed it at this speed) whenever I left off the gas to slow/stop and start coasting, I get the Check Engine light. It happens right around the 800 rpm mark. It goes away if I apply some brake or more throttle.

Anyone know why this happens?

EDIT: I don't get power surges or anything, just the light, everything else continues working fine.

[winfred]

do the stomp test and see what codes are stored, they may point to something

[CharlesAFerg]

I had this, I needed a new throttle body...

I had the problem at higher speeds though, or if i was going fast and let off the gas after about 3 seconds it would come on. It was aprt of my idle problem.

Although it went away the same way you get yours to go away, gas or w/e.

[markus]

my car is doint this as well. the stomp test doesnt work on my car so let us know if u find anything. does it seem to do it more coasting downhill? I have noticed that.

[winfred]

it may be something like a dead tps if you can't do a stomp test (assuming you are doing it right, as soon as you turn the key on stomp the gas to the floor 5 times within 5 seconds of turning the key on, some cars are a little tricky) get the codes read and see what it's bitching about

my car is doint this as well. the stomp test doesnt work on my car so let us know if u find anything. does it seem to do it more coasting downhill? I have noticed that.

[Macv]

So is this something that has been covered before? I could have sworn I remembered this being a previous problem.

[CharlesAFerg]

So is this something that has been covered before? I could have sworn I remembered this being a previous problem.

my car is doint this as well. the stomp test doesnt work on my car so let us know if u find anything. does it seem to do it more coasting downhill? I have noticed that.

Yeah and yea, NEW THROTTLE BODY fixed it right up, you even notice it when rolling down the street and you let off the gas, there seems to be more resistance... Also, I tweaked the mixture a bit.

[markus]

new throttle body? dont forget we have M60s.

[Macv]

there seems to be more resistance...

I have no extra resistance, just the light. As I said, there's no noise or performance errors.

[BillionPa]

it happens when the engine cuts fuel and the vacuum is strong enough to suck extra air in, throwing a "lean mix" code.

if your idle is fine, and you have no performance issues or excessive fuel consumption, etc, you can pretty much just ingore it.