Hi, I new to this a new evo owner. I just picked up the car today.

Car has highmiles and the problem I'm having Is with engine stuttering almost stalling when you put accessories on like ac. It will idle rough and spit and sputter revs drop. Turn ac off symptoms go away and engine runs normal.

Could have to do with a idle control valve or something similar?

Any help would be appreciated.

Thanks
Dan

 

Does it have cams? what are the mods? Do you know what tune or who tuned it??

 

No cams, Factory exhaust and to my knowledge no tune. does not appear to have been tampered with no tool marks on any of the bolts.

Dan

 

u might need to have it retuned to raise the idle or adjust some of the AC peramitters

 

id check for a vaccume leak

 

I will check for vacuum leaks to start.
Im going to ask a couple noob questions here please bare with as im new to these cars.

I thought that the evo used a MAP sensor not MAF? There for vacuum leaks should affect the car like on a MAF setup. My skyline uses MAF sensors and runs horribly when you have a vacuum leaks and when it had the same issue it was a icv valve

Is there a valve that controls idle on our cars? Most cars have a control valve that bumps up idle when accessories are turned on and there is extra draw on the engine.

The car ides about 950 rpm then drops between 600-900 with ac or other accessories on. If that helps

Dan

 

Evo uses the maf as its main reference so a vacuum leak would cause it to run bad at idle. Might just need a simple idle screw adjustment.

 

Good suggestion, but I don't understand why you would retune if car is stock? AC works fine from factory and ecu parameters shouldn't change by them selves.
A mechanical or electric sensor or controller not functioning makes more of a sense.

I find too many jump to tuning out the problem instead of finding the broken or malfunctioning part. Do you adjust or raise the idle if you have a vacuum leak to compensate or find the leak?

Dan

 

Thank you that helps alot I will search for leaks and then try adjusting the idle.
hmmm now where is that idle control screw?

 

it could possible be the idle air control valve to

 

hi again, long delay. Evo has been on the back burner for the summer.

I'm still haveing same issue runs like crap with ac/lights/heat on.

I replaced the IAC it helped alot now the car just runs badly not turning off.
I replaced most vacuume lines and retightened everything else.
Turns out there was a boost controller and a few other things installed on this car I found a old boost controller line that was going to the wategate.

Any ways has anyone had issues with misfire and rought idle when coil packs/wires are bad?

Just thinking more power being drawn with old coils might not make an efficient spark.

Dan

 

does your idle have lope? Could it be bad injector?