Mods are in my sig... the last thing I did was Walbro 255lph fuel pump.... as soon as I did this, I noticed that when I idle, every ~20 seconds or so, RPMs will drop from ~900 to ~700 (as if the car is about to stall) and then it will catch itself and bring it back up.

I have been tuned since then (Jestr M1), but the problem still exists.

It hasn't caused the car to stall yet, it just feels as if it's going to and then catches itself.

I don't know if this is a common problem. Now that I think of it, I did make one other change when I installed the Walbro... I cut out the side of my airbox cover like this:

Do you think the airbox cover is the problem or the fuel pump?

 

Its fine nothing is worng take it to jon have him data log your car real quick you should be fine bro.

 

thats normal, you can get that fixed whenever you get a tune

 

We all know the evo is everyones baby. But damn rpm drops lol dont stress it.

 

I'll log it and talk to John, thanks all

 

CLOSE THE AIRBOX!! I say that is your problem. Someone drilled holes in the top of the airbox, and had same idle issues. Don't need a tune with just dropping in a walbro.

AIRBOX HOLE IS 100% OF YOUR PROBLEM BRO!

 

hahaha that is ghetto.. your not getting more air.. if anything your filter's capability is decreasing by the minute.. as is prone to get dirtier faster..

We all know what a dirty filter means.. less performance.. and indeed that may be your issue..

 

get a new air box cover, because right now the engine is sucking hot air from the engine bay instead of the outside air.

 

And what do you think every aftermarket intake does? I've datalogged this cutout and the cutout makes a negligable difference in air temp, while increasing air volume.

My friend's HKS Racing Suction takes in air 15 degrees hotter than mine

 

An aftermarket intake has a known intake path. this one looks like you can suck air in the snorkel, and have the air blow BACK OUT the newly fabricated "side hole". I say you put the normal airbox cover on, or just go cone intake. Don't fab the boxtop. That is the problem here, I am pretty confident. surely would have different characteristics at idle, and WOT on the road. Follow the path of the air getting sucked in............it won't hit the side of the intakebox, then down thru the filter, because the incoming air is blowing right back out of the"modified hole! Only SOME, not ALL, of the injested air is getting in the motor this way.

 

could be the hot air from engine bay.....
i know cams make the rumble like thier about to die

"DUDE YOUR CAR IS ABOUT TO DIE!"

-guy with cams-

"no, no my friend, its more alive then youll ever know...."

 

Wow you datalogged it.. so you pretty much got it down packed where is how much of the box was suppose to be cut.. Why not cut a inch more.. datalogg it maybe you'll see even more performance..

This is by far not the smartest idea in terms of performance enhancement.

If you are looking into keeping the stock air box for a bit, I suggest a drop in filter.

A drop in filter outperforms this silly idea and will actually give the performance you seek..

 

I have a drop in filter.

Why don't you take a look a long hard look at this thread where you can read what multiple people have tried, logged, and tested... instead of saying "WHOA WHOA ALL AIRBOX MODS ARE BAD, WTF ARE YOU DOING MORON?!!??!"

https://www.evolutionm.net/forums/sh...ghlight=airbox

 

I had to read your post a few times to make sure I was getting it right. There will be a vaccum above his filter anytime the car is on. Whether it be at idle or during loading. So, it looks to me as if air will be comming in both sides of the box and probably MORE air through his new cutout, seeing how that is the path of least resistance. So air blowing through the other side really isnt an issue. The issue I see is whether or not he is tuned for an aftermarket intake.

 

Show data or a link to back up your assumptions bro.