lean when let off throttle

[crazyquik22023]

I am having a slight tuning issue whenever I let off the gas when I am driving on matter what rpm I let off at or how fast I am going my wideband goes all the way lean and will stay there until I give it more gas. When I am at idle though when the car is not moving the AFR is around 14.2-14.6. Fuel trims are adjusted good. The car holds idle good but the ISC position will not stay at or around 30 like it is supposed to. Its more like 60-70. I am using dsmlink with narrowband simulation with an autometer wideband. I also did the FIAV mod and still using a ISC sensor. Any ideas to why it is doing this would help. Also if i put it in neutral while driving the rpms stay at around 1500 until I let it idle for a few seconds then the idle drops back to 1000 where it should be.

 

[GRAVEDIGGER]

So what's wrong with that?? Every time you lift the throttle your wideband is supposed to read lean. Sounds like normal operation to me.

 

[mike96]

This is normal. The ECU shuts off fuel when you take your foot off the fuel injectors while leaving the car in gear. As far as i know all cars do that.

 

[FearlessNick]

Yea, it seems klike you would want this. This is when your tuned? My car isnt tuned and it goes every where,

 

[milby43]

Yes, when you let off the throttle. You will go full lean, because the ECU cuts fuel.

As for the idle rpm issue. Sounds like a bad IAC (ISC). Try disconnecting it, and driving.

Disconnect the plug, set your idle, and then drive it around.

The ISC could be bad and stuck some what open.

 

[FearlessNick]

Yea, it was the first thing I looked at when my idle was real bad.

 

[crazyquik22023]

Thanks for the responses. I know that the car will go lean after you let off the gas but I always thought if you let off the gas while you are driving and you are cruising/under a load, while giving it no gas, the car should not be all the way lean. I figured it would be somewhere close to 14.7. I guess I'm wrong.