First off, I have done plenty of research on this before creating this thread. Hopefully it is something mindless that I missed.

Background info:
I've owned my 2003 Evo for a few months and a few thousand miles. Bought the car with full bolt-ons, big turbo kit, buschur tuned on stock ecu/maf/93, kelford cams, stock block, etc... pretty far from stock, most of which I haven't installed/worked on myself (yet) so there is quite possibly room for error somewhere along the line.

Problem:
-Inconsistent/Jumpy/Erratic Idle: Mostly on cold start, occasionally it will dip down at a red light when warm
-Car will start up, idle will move up and down rapidly then die after a few seconds. This happens two or three times on average before it will hold an idle on a cold start.
-After the first 2-3 gear changes (after pressing in the clutch to go into neutral or reverse to first) the car stalls.

What I have done so far:
-Checked IAC (pulled it out of the throttle body and cycled the key to make sure it moved/visually inspected)
-Cleaned MAF
-Tightened all clamps on IC/Intake piping
-Visually inspected, sprayed starter fluid around to check for vacuum leaks.

I recently bought a tachtrix cable so I will be able to do some logging and what not soon. I am suspecting that either my diverter valve (Tial QR) has the wrong spring, my MAF/turbo inlet pipe is causing for incorrect readings (it's pretty ghetto), i have a vacuum leak that I missed, or the tune is a bit off (maybe because of weather, or previous owner changing parts post tune?).

Any input is appreciated!

 

replace the worn throttle body shaft seals..clean out the throttle body and egr valve & see what happens..you should also do a boost leak test!

 

I will give it a go. I've been meaning to do a boost leak test and buy a wideband but I've had a pretty hectic schedule lately. It smells like the car is running rich at idle though.

 

does the car drive smooth other wise?

 

Yes, it drives completely fine. The only time I have issues is on cold start and the occasionally bogging at idle. I'm sort of stumped, I wish I had more time to diagnose it and it's been like 30 degrees outside the past few days.

 

thats how mine is.. if you do a full pull on it does it hit full boost without any issues?

as far as i have asked around its this list of options:

-IAC
-My 1450cc injectors (Im E85)
-Possible crack in my headers
-My bov (Because Im VTA)
-MAF/Throttle Body Shaft Seals
-Vaccum/Boost Leak

I dont think I left anything out.

 

What is your afr at stop? Being it is getting colder out the less dense air could be the culpret. I know my car does that from time to time but as stated above I am on e85 as well.

 

this is even when it is warm (80+) outside.. reason i know this is because i havent found the problem since before summer im guessing its the vta.

 

Could be but you didn't answer the question hahaha. What bov are you using? I know when I went to the Tial I had issues with wrong spring and the bov wouldn't stay closed but it surged all the time. How about idle? what does the car idle rpm wise?

 

i have an hks, but i just got a tial and havent had a chance to put it on. the idle is set at 1500 but it doesnt help the dip that happens. it still happened when the idle was set at 1000

 

Reason I asked was because my bov wasn't closeing all the way. I had similar effects. One way to check is to block off the bov line. Just fold it over and zip tie it and see if it changes. Once I figured out the spring was wrong I got the new spring and it helped some. I would also check your cold start in ecuflash. Honestly I would start there first maybe it needs to be tweeked some.

 

well i think thats fine because my tuner said to turn it to on for like 10 seconds and then back to off, and then turn it back on and sometimes it'll start right up but thats just with the car starting & not after. the car can be warm as itll get and it will still do this. ive tried the pinching the hose trick and no luck. but it wolnt hurt again. as far as ive read alot of people are having similar problems and nobodys found a solution

 

Other things I would check is your tps, check to make sure the voltage is within specs, your idle control valve I know mine went bad, and if that fails to find error, check your biss screw to make sure it isn't leaking and make sure it is not screwed in to far or to short. Those are simple things I have had to do in the past and it can't hurt. If you need the specs for the tps lmk I'll post them for you.

 

oh yeah i forgot to mention that but im sure i should have but whenever it "dips" down and the rpms drop my gauge cluster dims out so it might just be the voltage. i have a mini battery and never have liked it.. always wanted to relocate a regular size one in the trunk. so whats the tps? and could it be the alternator?

 

I had this problem before. I ended having to up the idle within the ecu. It'll still bog during cold starts, and having the AC on while driving can cause it too. You main deal isn't just the BOV, but your cams. My cosworth 272 cams do it and if I leave my car alone in the cold, it'll stall out.

Problem is common. Up the idle, let the damn thing warm up.