So do I was driving my car. I was in third gear and decided to do a pull. Right as the car got to full boost it started to get really bad turbo serge on me. I took the car home and have noticed that the car is running super lean right now.

Since I have gotten home I have replace the vaccum lines from my wastegate to the boost controller, from the turbo elbow to the boost controller, from the BOV, I have replaced the plugs with brand new NGKs BP8RES gap at .019 (cars on e85). I have also performed a compression test on the car and have gottem 150 conpression across the board. Even with doing this the car has gotten worse. It is trying to idle between 2000-2500 rpm and it is idle surge. I checked the throttle body cable and it is not getting hyng up on anything.

I gave up on it for tonight but tomorrow I am gonna pull off all the charge piping and inspect them and the couplers. I wanted to put up a post and see if anyone else has any ideals on what I should do.

 

Idle issue makes me wonder about egr or iac related issues?

 

I would do a boost leak test. How many miles on the Evo? When was the last time the Evo was tuned?

 

Egr is deleted and blocked off. Car has roughly 62k on it. I just had the E85 map created about a month ago.

 

do you have a check valve on your brake booster? I just popped the diaphragm in mine by boosting it and not having a check valve.. oops... do a boost leak test for sure like deylag said...

 

I've got the same issue.Mine's revs go up by itself when the clutch is engaged and then you have to blip the throttle to get it down.I've even replaced the iacv,but it's only made the cold idle better,but the problem is still there.

 

i got the same problem as MrJuls as well, replaced pcv and TB shaft seals, and still does it, ive pretty much given up on tryin to figure it out, just hope when i get tuned it changes sumthin

 

I'm going to try and check the accelerator cable and let you know.Or even if i get a solution i will keep you posted.

 

Ok so spent the greater part of my day working on the car. I found that one of the bolts for my intake manifold was loose so i tightened it up. Also the vacuum line from the fpr to the im came disconnected. I replaced the IAC and the lower intercooler coupler for the turbo elbow and the car doesnt seem to be sputtering anymore. But my idle is still messed up. It idles normal until you give in gas but afterwards it raises to 2k rpm. It also serges about 2 or 3 times when you let of the accelerator and then settles at 2k rpm.

 

I'm going to spend the whole of Saturday if need be to find the fault.I'm going to start looking for a boost leak and check all vacuum pipes and boost pipes etc.I've got some dye-penetrant and developer so i'm going to test all the rubber ic bends for tears.Next up is taking it to my tuner and checking for error codes,and maybe again just adjust the idleing electronically.

 

Ok so finally got to do a boost leak test today and fixed all the leaks. All and All I found about 5 of them. The turbo is no longer hiccuping anymore. Hits 30lbs of boost and holds it beautifully. However I am still having the idle issue and idle surge when I am letting off the gas. While I had the turbo intake pipe off I cleaned the maf too and nothing.

I took the car too autozone today and had a code read. It stated that it was running too lean at bank 1. I am really starting to wonder if this issue could be fowled front O2 sensor because my AFRs are all over the place. Anyone else think this could be the cause???

 

Mine was the dirty throttle body.It had carbon build-up so the butterfly couldn't close properly.I used an old toothbrush and some clean green.

 

I didnt see any build up in mine when I had it off the other day but its worth a shot.