I've been searching and eliminatiing potential causes for a few days now but the problem is persistent.

Car: 03 Evo w/ ~110,000 miles
Mods: Vishnu turboback, vishnu cam gears (-5, -5), Vishnu Xede (360 non-smart program)

Problem Description: Car has been running under the Xede & -5:-5 settings on the cam gears for the better part of 6 months with zero issues. On Friday I left work and drove about 20 miles to the hardware store through traffic with no issues. Upon leaving the hardware store the car did not start on the first try. Second time it fired right up. Car was idling and running fine but within the course of 2-3 miles it wouldn't idle. I two footed it home where it promptly died in the driveway. Restarted and the problem repeated. No codes were thrown.

Went for a drive later that night. Car behaved normally save for lack of an idle; pulled strong, made boost, no smoke, etc...

Steps taken thus far (tested for idle between each step with no luck):
- checked all fluid levels/consistency,etc...
- reset the ECU (twice) .
- pulled mass air sensor and cleaned with the proper cleaner.
- checked for miscellaneous vacuum leaks.
- verified base timing and -5:-5 settings on cam gears.
- reflashed vishnu xede with 330+ map.
- reflashed vishnu xede with 360 map.
- removed vishnu xede.
- unplugged/replugged IAC

After all this the car still wouldn't idle. I turned the idle adjustment screw counterclockwise 4 turns realizing that it is a band aid. Car idles fine at "stock" rpm now.

All of this points to a shot IAC in my mind, but I'm not getting any IAC codes. For that matter the only codes I'm getting is the P0335/P0340 code (crankshaft/camshaft sensor faults) and that is only when the car dies from the low idle. I think those codes are more of an effect of the car shutting down verses a cause. Crank sensor is not cracked. With the idle adjustment screw opened up 4 turns, there are no codes being thrown and the car appears to be running fine.

If the IAC was shot... wouldn't the ECU throw a code? What is the normal failure for an IAC?

Appreciate the help. Thanks to those who have already posted/answered previous idle topics. The search was pretty beneficial.

Fitz

 

how about your pcv valve line comming off causing rich idle making it die.
Also it could be a vishnu problem, Heard many problems with them. Even magazines had problems with them.

 

vaccum line? mine popped off from a boost line and wouldnt idle

 

PCV line is ok although I am changing the PCV out on Monday for giggles.
Vishnu Xede has been removed.

Haven't found a loose vacuum line yet. Would expect the car to still idle rough even after fiddling with the adjustment screw if it was a vacuum leak.

Thanks,
Fitz

 

check your egr lines there are three of them 2 behind the throttle body and one on the opposite side......change your blow off valve.....???

 

Yes there are some vaccum lines that come undone sometimes underneath the intake manifold. You may need to look from under the car up thru the t-case area.

I would do some logs and see if your TPS is acting normally too.

 

Thanks guys. I verified all the EGR lines as well as any other vacuum line. No leaks found as of yet. TPS sensor also checks out ok.

I'm going to try to source an IAC and swap it out. The car runs beautiful as long as the throttle is opened even the slightest of amounts whether it be with the throttle adjustment screw or the pedal.

Has anyone taken their IAC out? Anything I need to worry about? I think I may try cleaning it before I replace it.

Thanks,
Fitz