Here is the issue, I had my IAC valve replaced due to the other one failing. After replacing it, my RPM's finally dont hang around 1500 at idle and is now adjusted to 900 steady. Everything is good at idle, no issues.

The problem I am having is whenever I am on the throttle and put the car in neutral say to coast to a stop, my RPM's drop to 100, sometimes even stalling the car out. If the car doesn't stall, it drops and feels like it might die then instantly rises back up to normal idling state. This happens within a few seconds every time whether it falls to low RPM's and feels like stalling, or it stalls. The throttle body is 100% clean, the sensor is brand new and is keeping the car idled fine, it is only when I rev the car up, or take it out of gear when driving from half throttle or more.

Any help would be greatly appreciated.

 

Really need suggestions

 

Intrested to know myself..

 

My car is doing the exact same thing. I was thinking it might be the IAC, MAF or front O2 sensor. Haven't had time to look into it yet. Hopefully somebody can chime in with some help.

 

9 times out of 10 the issue you are having is caused by incorrect adjustment of the IAC. It can be setup correctly with either Evoscan or a MUT tool.

 

if you are throwing a CEL, see what that gives you. i would also check to see if you have a boost leak more particularly on the intake manifold.

 

Thanks for the insight. I'm glad to know I'm not the only one with this problem however so we can find a solution to this. I don't believe I have a boost leak as I can boost properly and my car was just recently logged using Evo Scan. I could check the IAC valve again, but what do you suppose I try adjusting with it? Are you saying to mess with the idling screw, because at the moment I hear a hissing sound coming from the screw when I play around with adjusting the idle. Im not too sure if this is normal or not?

 

To set the base idle you need to park the stepper motor IAC in Evoscan, then adjust the BISS screw so the idle is 850. Adjusting the BISS screw without parking the stepper only makes the stepper motor try and compensate.

 

subscribed, same exact issue.

 

So what your saying grayw is that I need to go into Evoscan and adjust my idling through there? So where exactly should my idling screw be at when I begin the test

 

In the throttle body - sorry, I couldn't resist.

I idea is to park the IAC at midrange - so that it has plenty of travel when let loose to control idle. The old Mitsu cars had a plug on the firewall that you grounded to park the IAC. I miss that. Oh well, this is progress I guess.

 

So should I try messing with the screw a bit more? Because when i start bringing it up i hear more and more start to escape and make hissing sound get louder. Im not sure if im bringing it up too high or not. If it helps any, the old IAC valve broke on the previous owner so he decided to go cheap and just put the screw all the way in and it was idling at 1,500. Not sure if this could of led to further issues.

 

I have a similar issue, but I've never stalled because of it. It happens at idle and only sometimes. It will drop from like 800ish to about 300. I've never had a CEL, but I'm thinking that I'm in need of a tune.

 

Just curious, are you blowing off to atmosphere?

 

interested on this as well. i get this occasionally. not to hijack but where should the BISS screw be set. completely tightened in?