I have never NOT had issues with my idle on my EVO since I got it.Â* I think this is one reason why people say that buying a Mitsubishi (especially a DSM) makes people mechanics...Â* I have had highly modified Nissans and Hondas and I have never had to deal with the bizarre stuff I have had to deal with owning an EVO.
Regardless, there are two main things I have done with the dipping idle.Â* 1. is to have my tuner adjust my tune a bit.Â* This sent my idle to 1100, which is OK but not my desired idle but with EVOs, I guess you just have to pray to the gods of old to hope your idle is consistent.Â* One summer when I first had my EVO, if I turned on my AC, every time I would pull up to a light, my idle would drop and my car would die.Â* Scot Gray does my tuning and he just did a couple magic wand waves and everything was fine.
Also, I have adjusted the idle screw thingy.
[pics taken from Road Race Engineering].
I still have my idle drop off now and again but it usually only does it when I pop in the clutch unexpectedly in traffic...like if someone in a Prius randomly slams on their brakes or something... but it never dies.Â* In any case, my EVO NEVERRRRR has a consistent idle.Â* Sometimes, I will wake up and drive 20 miles to work with my car idling all buttery at 900-1k...then I will go to lunch and the shit is at like 1500 to and from lunch...then I will drive home and it will be fine again but around 1100 all the way home.Â* I obviously have OCD and this bugs me but it seems unfixable, so you just have to learn to check your EGR, check other vacum hoses if your vac reading it off the norm, then I would check the idle screw and play with it before fiddling with more complicated stuff like the MAF or your TPS or any other random stuff people will tell you.
I try to work on my EVO as much as possible and this is still a struggle for me, with my old engine and my new engine, with my old TPS and my new TPS and all other stuff checked and gone over x100000.
Basically, what I do is:
1.Â* Go home, park, disconnect the battery.
2.Â* Relax for a while, do whatever while the car cools, then check all hoses (especially EGR) and then reconnect the battery for the next time I drive.
3.Â* The next time I drive, I bring a stubby phillips head screwdriver and if the problem is still there, I will stop in random parking lots and tighten the screw or loosen the screw to get the desired idle.Â* I play with this by turning 1/4 turn at a time but you can really feel it.
4.Â* If this doesn't help, I will usually throw in the towel and seek help at RRE.
Last, the dip in idle has been on my EVO since I got it and it never goes away but you can mess around so it only happens here and there, and you can make it so it does not make your car die.Â* That is my experience anyways...