The Problem,

I have 272s...
Anyway, when I turn the AC on it will eventually die. Usually this happens as soon the radiator fan kicks on. I set the idle to 1100 rpm to see if that would help. I also replaced the ISC (Idle Speed Control Valve) on the throttle body.

Possibilities are; I have a fried ECU
Something is wrong with the wiring harness
The new ISC is also broken.
I have a bad tune... not enough fuel at idle.

Any ideas? Opinions? Questions? Please let me know.

 

how much hp do you have, if you dont have high hp to go with the 272's, it will do that. They have higher lifts and are made for the high rpm range, theyre known to idle at low rpm thats why when you turn the A/C on, it dies. Normally the cars idle drops with the A/C on but not much but enough to be concerned, the A/C robs hp. The ecu will also adjust to the raising of the rpm. I need a second opinion on this tho...

 

no fuel pump or injectors?

 

I have a Walbro 255, stock injectors. Car made 300 awhp with a boost leak and a incorrectly installed EBC. I fixed the boost leak and corrected the faulty installation.

 

man you jumped straight to the big guns without the bullets

 

I'm a nub to this, but I thought that the 272s created less vacuum than stock, so why would you be surprised to stall when the AC is on? You can try raising the fuel a bit, I've heard that "catches" it. Maybe someone who actually knows could comment?

 

There are 4 people in OK besides me that I personally know that run 272s with stock injectors. 3 have 2003 Evo GSRs and 1 with an 05 MR. That doesn't seem likely, though it's possible that I may not have enough fuel or vacuum signal.

 

What EMS are you running, and are you still on MAF or on MAP now?

 

how much whp do you gain from cam gears? is all that trouble worth going through all this crap?

it's not even this, they have all sorts of problems with almost all combo cam gears.

 

I got a tune from Mark a turbo trix this past winter. It's using the stock ECU. I'm thinking of going to some sort of EMS, but it's hard to figure out a solution when your not sure of the problem.
I may take it to GSC while I'm at Fort Jackson this fall or Alamo when I get to Fort Hood. I'm tired of tinkering with this car.

 

If it only happens when you turn the AC on then it is the AC compressor dropping your engine rpms when the AC clutch engages. I don't know if there is a way to get a custom flash to counter the rpm drop. I've heard a 272 idle. The low rpms are crazy. Sounds like the engine is stumbling.

 

Are you getting this problem when coming to a stop? Try the stock BOV and see what it does.

 

I tried a stock BOV and that didn't help. I'll turn the AC on and then the radiator fan kicks on about a minute later. This causes the car to stall. A tech told me that it could be my ECU has go problems or my ISC is broken.

The car will idle all day when the AC is off.

 

My evo and every car I've had in the past, the ecu increases the engine speed when the a/c compressor kicks on. Sounds like your ecu isn't doing that.

 

Well like I suggested previously, it still might be something voltage related. When I turn on my AC I get a noticeable voltage drop, and the revs decrease. This is with 264s, but I do not stall.

Did you ever check the grounding of the car? I forget if you have a grounding kit installed.

Otherwise, I would say there is something wrong with the cam installation.