I know there are tons of threads on this topic but i would like to share my experience and hopefully it will help someone.

2012 WW Evo X
56xxx miles
AMS bolt on
Kasey TUNED North Carolina Dyno Time Speed Works
No CHECK ENGINE LIGHT

I was on a road trip to North Carolina. When i was coming back home, i pumped gas and started the car up and turn my knob to defrost and turn on a/c, then my car would surge like crazy from 1000 rpm to 400 rpm and keep bouncing till it dies. So i turn the a/c off, turn the knob to feet, and the car ran perfectly fine. It stop surging. So i decide to turn knob to just defrost with no a/c and the car surge again! So in order to make it back home, i turn off a/c and had the knob turn to blowing feet. When i got back home i read and read and read and research everything i can about Idle surge a/c defrost on. Many says FPR vacuum line, A/c overcharged, TUNE on a/c table isn't adjust correctly, dirty Throttle body etc etc etc..... My FPR vacuum line was still connect, did a boost leak, no leak, went to the shop to check my a/c and they said your compressor is bad and i need a new a/c system, because my compressor would kick on and off every 2 sec. No i didn't redo my a/c system. Couldn't be my tune, cause it drove perfectly fine with a/c on. There was other thing i checked.

Symptom: A/c ON it will surge 1k and drop to 400 rpm
A/C off but Defroster on it will surge for 800rpm to 400rpm
A/c on, the a/c compressor kick on every 2 sec
Only happen when a/c compressor is in use

So I also read something about air filter and the air filter shield, to check those. Which i did and nothing out of the ordinary. Air filter still look clean and the air filter shield still in the same place, hasn't moved.

Went to autozone and bought me a can of CRC mass air flow sensor cleaner and clean the **** out my MAF sensor. Let it dry and threw it back in.

THE CAR RAN PERFECT!!! Drove all day with a/c on with no idle surge, i mean it drove like a 345 WHP evo!!!! Then when i was closing my restaurant at night, the car surge again with a/c on idle.

So i order a new MAF sensor and install and the problem never happen again, it been 2 weeks since i install, so i know it safe to say, my problem was the MAF sensor.

The biggest headache ever to find the problem. But i guess Mitsubishi MAF sensor are not really reliable, i mean the car only has under 60xxx miles on it. I don't push my evo x, more cruising if anything.

In closing, i hope this help someone who has similar problem and it helped them fix their issue. I really couldn't find any solid thread on idle surge a/c on defroster. Any question feel free to PM or post on here. Thanks

 

Glad that after all that headache you were able to fix the problem. Nice job! The biggest headache that I have found the problem to was a lean spot in the power band that could not be tuned out. It ended up being fuel rail harmonics screwing up my afr's at a very specific RPM region. The solution was a fuel pulse dampener. Just wanted to note that for the future if anybody comes across this.

For the record, I think that would make a good thread! " Biggest headache problems you've ever had and the solutions." It would be the single biggest thread on evom in no time at all.

 

1 post - problem . Symptoms and solution.
Thanks Charlie.

 

Thanks Guys!! I only like to post on thread on problem i have experience and what i did to solved it. I gave up asking for help on forum because to many **** people online. Especially honda-tech.com . To many kids and don't know what they are talking about. But on EvoM, tons of mature guys who really supportive and helpful. I usually post a DIY or Biggest headache problems you've ever had and the solutions. i think i have like 3 post count. LoL but been a member since 2012.
Thanks again guys for the kind words.

 

Maf is the problem I changed mine out twice already evo x has **** sensors they will go out if the intake or sensor mount itself vibrates to much