I have an AEM EMS so the basic ecu stuff is out the window. The throttle cable was fine.

 

Well I think that may have something to do with it!

 

[QUOTE=s2krev,Feb 23 2006, 09:58 PM] I have an AEM EMS so the basic ecu stuff is out the window.

 

Sorry I implied it in the original post but your right I didn't state it straight out.

The sensor on the side of the IM is the rotoray air control sensor correct? would the symptoms seem right for this sensor to go out?

I think it is that sensor because it makes a high pitched humming sound even when the car is off. I don't remember it doing this before. When I unplugged that sensor the sound went away immediatly.

 

 

Does it run when this sensor is gone?

 

I unplugged the sensor and tried to start it and it did the same thing that it did before.

 

Well then you can assume that it is not the sensor, I would see if you can isolate the problem. I dont have any more advice being that it is a stock ecu and I havent seen an EMS on an s2000 yet. Sorry bro.

 

I thought it would be the other way around. If the sensor isn't working "fried" it would send no signal at all. So having it connected or disconnected would have the same effects.

I just went and loaded a base map and have the same issue. That pretty much rules out the EMS.

Would a bad IAC cause symptoms like this? or map?

 

I think the IAC (Idle Air Control) valve, which is a stepper motor, is remaining wide open or there is a major vacuum leak. This is the equivalent of the throttle valve partially open. The reason can be one of many.

1) Carbon deposits in the IAC are causing it to stick in the wide open position. This may be cured by spraying carb. cleaner in the opening just behind the throttle valve. You can also remove the IAC motor a check for any obvious reasons for it sticking.

2) The IAC is acting normally according to the sensor readings that are received by the ECU. For example, if the coolant temperature sensor is indicating that the cooloant is 10 degrees F, the IAC opens wide and the injectors run very rich (~9:1 or so A/F ratio) at startup to keep the engine running during cold start. You can check the voltage output of the coolant temp. sensor and compare it to a voltage vs. temp. chart.

3) There is a major vacuum leak in the engine causing air to enter the manifold. Check for any obvious vacuum leaks (i.e. brake booster hose, vacuum lines, etc.)

4) The ECU is sending a incorrect signal to the IAC motor.


Let us know what you find.