I've noticed this in the past very, very slightly while decelerating where the car gives a faint increase and decrease in the car's deceleration rate.

Now I took it to the track and after an ugly run of missing 2nd this problem became more severe where the idle will climb to 2K initially then settle at 1100 RPM or it goes into a hunting pattern of 1200 to 1600 over and over. I can also feel it upon deceleration.

Also while occilating 1200 to 1600 RPM, the tach and boost guage are about 90 degrees out of phase - the psi starts to climb when the rpm is on its way down.

I checked the EGR lines not the valve itself, the crankcase ventilation, and swapped BOV (cured someone elses problem like this - not mine) but I have a feeling it may be in the fuel mgmt arena.

Anybody have idears?

 

I'm taking the EGR valve out tomarrow and cleaning it. I think some crud got in there - when I missed second at the strip, I over reved abit. This in conjunction with methanol loosening 30,000 miles of buildup.

If that doesn't work I'll start with throttle body cleaning, then look for a plenum leak.

I just wondered if this problem sounds familiar to anyone else

 

One more try

Man, as usual, I have to troubleshoot myself again

 

Wow I'll be better off asking a question about why my boost is erratic when MBC is backwards.

Well, got the 507 (high rpm) code last night - time to ohm out the motor coils and clean the TB.

I'll keep you, if anybody, posted just in case someone decides to search for something similar in the future.

 

Without the help of anyone here.
Well I removed the Idle control (stepper) motor and the end of it (foot) was melted!?

Anyhow I called mitsu they said $320, I said kiss my butt,

I remebered Greg (GSC) had an 03 plenum at is shop with all the stuff attached, and he sold it to me cheap - Thanks Greg.

Question is, why did the stepper motor foot melt.

 

Hey steve, this is Cory,
I just came across this post. Do you think the alky had anything to do with the melted piece? I would like to check it out and see what happened. My car has a little bit of a rough idle too but I really haven't checked into it yet.

 

I think In combination of a n incorrect vac setup with purging the system cased the methyl to accumilate and it caught fire.

I might replace the TB too.

 

ahhh.... i think this might be my problem, also. My idle is very bad right now, and there was a burning smell when the problem first started, and I was running meth at the time. I bet i fried the stepper motor.
Thanks for the heads up. LOL anyone have one to sell.

 

ahhh.... i think this might be my problem, also. My idle is very bad right now, and there was a burning smell when the problem first started, and I was running meth at the time. I bet i fried the stepper motor.
Thanks for the heads up. LOL anyone have one to sell.

 

 

clean the throttle body with crc tb cleaner...
...had a problem with irratic idle in another turbo'd car...and this fixed my problem 100%

 

Back from the dead You're troubleshooting has let me to believe my idle stepper motor is bad The end of mine has a lot of carbon and appears to be melted as well :|

I'm also running alky and desperately looking for a good picture of how it should look. 320 is way too much for this thing. If anyone has one for sale and see's this PM me

PS: Any conclusion C6C6CH3vo?

 

damn this sux....i wonder if my idle stepper motor is bad too.....im not running alky but it started happening after i put some pump 101 in my car. I halfway cleaned out my TB but ran outta carb cleaner. it was just stalling completely now it'll at least idle at 600-700 rpm.

 

The end should look normal, mine looked like it was through a blender then a torch, the idle screw I pulled out to find it was about twice as long as it should from melting, also there are some other internal plastic parts (small flapper) I had to replace from a new TB I lukily found.

It's been over a year since this but I still pull the stepper every month or so when my idle is screwy to find it's still OK and must be due to AC or over flashed ecu or something....


The dyslexic title cracks me up "My is idle"

 

I have this problem due to meth, went thru 2 stepper motors. Anyone have a fix a resistor or something. I tried in the stepper table, it will work for a little bit and then come back.