Sir_Skurpsalot

When running the A/C, sometimes when I push the clutch in and hold it (as if approaching a stop, etc) the RPMs will fall to around 400 or so and then it will bounce back up, sometimes bouncing over and under 1000 several times before settling. Other times RPMs will fall all the way and it stalls. It seems like the longer you drive the car the more frequent it becomes (heat related???). No error codes. This problem started after getting the engine rebuilt last year. It was rebuilt with a pre-assembled stock Mitsubishi short block from STM and Tomei 272 Camshaftss (TOM-TA301B-MT01B). The car also has a Mishimoto radiator, other than that it is completely stock. I've given the shop multiple tries to fix this problem, previously they replaced the MAF sensor and O2 sensor and thought it was fixed but it was not. I replaced the IAC valve myself to try to fix the problem and it made no difference. I recently gave it back to them for the better part of a week and they could not figure out what is going on, they mentioned the AC compressor, accessory belt, alternator, cam position sensor, throttle position sensor were good. I'm not sure what else they tested. Any ideas?

Geforce_EvoIX

hey you might need to look into the tune or get tuned, 272 cams do give some issues like this I've read. Check your idle settings, if ac is off and its set 1000 check if ac on is set 1150 for example.
Also try disconnecting your battery, should be fully charged too, for a decent amount of time, 30 min, to let the ecu reset and relearn idle. If it idles fine then the issue happens - sensor problem. If it doesn't help right away - mechanical problem (iacv etc).
Start the car AC OFF - let idle- turn on the AC - let idle - and do NOT touch the gas pedal. The car will re-learn it's idle after a short period of time. Check some videos
you might need to adjust your idle BISS screw.
check vac leaks

check this thread out
https://www.evolutionm.net/forums/ec...h-decel-4.html

schuhie

This is something that is a known issue on these cars. @ViciousLSD and I have been trying to find a solution for the better part of year on your cars.

We have tried sensors, idle changes, BISS settings, etc. without much luck.

Like Geforce said, check for vacuum leaks, test the IAC you replaced and make sure that's working, log the cam and crank sensor to make sure there are no oddities. And if you find a solution, post it lol. There are for sure 2 other people looking into this trying to find a solution.

ViciousLSD

iTrader: (2)

Stock engine & tune, really? EGR and EVAP all installed? That is interesting.

One thing (new to me) I'm "a little better off" is my cut-off is 2k rpm compared to this guy. I can move the car in traffic maybe up to 2.5krpm and clutch-in has no issue
Just reving the engine to 3k and watching the needle drop, it definitely has a slight rev-hang at 2k which is cool, but I dont know which setting that is