GEMS - General Engine Management Systems Ltd - Forum

Greetings,

I am running a GEMS version S2.80 on my 2002 Evo 7, and properly tuned. I have had an issue once with my idle stepper motor not working properly, and I had to replace the servo. I bought a brand new one, installed it, and it was working again. Now 3 months have passed, and again I am seeing the same symptoms as the last failure, which are: On engine warmup, idle speed is not rising to where it should be. Changing the AIT idle table bears no effect on the stepper motor. Switching the A/C on does not turn on the idle stepper motor to compensate for the additional load, etc. Basically everything is pointing towards a stepper motor issue.

I am worried that just replacing the idle stepper motor will not take care of the issue. It seems something else is causing the motor to fail after a while.

Have you had these problems occur before? Can the ECU possibly be sending the wrong signal to the stepper motor which, in time, can cause it to fail?

How can I remedy this?

I appreciate your input.

Karl

Karl,

Is your idle motor open in Anti-lag mode? This can cause a heavy build-up of grime, that can prevent valve from resetting and generally slowing it down. Regular cleaning could help, watch out for spring, so disassemble in clear plastic bag. Also reducing the stepping rate could help, "Idle Rate" option typically 40 to 48mS.
In extreme cases the extra work load might damage the motor windings, to help prevent this check that the "Idle P Save" power save option is on.

Rich A

Rich,

thanks for your detailed reply.
Do you think I can save the current motor or should I buy a new one as a precaution? I have not removed it yet from the car since I am out of the country.

Should the motor be cleaned with a damp cloth?

To answer your questions:

- yes the idle motor is open during ALS mode. I set it to 252. I use a very mild form of ALS, since I do not have JOT. I only use idle motor and SAS modes (the car is being driven on the street). I also use ALS very seldomly. along with launch.

- my stepping rate is at 96ms if I recall correctly. Is that a problem?

- Idle P Save is not checked. I will make sure to put it back on.

Let me know if there is anything else I should watch our for.

Karl

Karl,
Yes, I would keep a spare, if using the idle motor for mild Anti-Lag. You can check the winding continuity with an Ohmmeter. The central pins (2, and 5) are common for the rows each winding is about 30Ohms cold.
96mS for Idle_rate is 1/2 usual.
The carbon soot build up can be removed with most solvents but damp cloth is good start. Also check plunger is free to click round.

Rich A.

Rich,

thanks. will give it a try and report back if I encounter problems.

Karl