Addex

Hi guys

its been 4 months now and I cannot for the life of me find issues with my evo 8. The car has been to countless mechanics and they have no idea. You guys are my last hope.

Issues with the car listed below

- Exhaust sound weak and strained/restricted from 3000rpm and above. Usually it screams and sounds awesome when coming onto boost. That sound is now long gone.
- reaching full boost at 4500rpm
- Incredibly slow spool
- Backfiring after boosting
- struggling to reach 15psi, will drop off to 12 psi then shoot back up to 17psi by redline.
- Other times it will spike to 18 psi.
- Rich smell from exhaust
- extremely Poor fuel economy
- Poor boost response
- Car feels like its hesitating on fast gear changes. Like it will hold back at 15 psi and struggle to hit 16 psi.
- Engine sounds rough at times.
- Car feels better if I gradually apply very light throttle.

Things I have tried listed below

- Found the EGR leaking. I have removed EGR completely. Blocked off all necessary plugs.
- GFB plump back bov leaking from flange. Although I have tried to install the bov backwards for 1 lap around the block to see if it holds boost better but issue still remains.
- Replaced cat with high flow cat.
- Replaced intake pipe
- Changed spark plugs
- Changed to jdm coil packs
- Have taken the car to exhaust place to see if I had an exhaust leak but cant seem to find a leak

Mods done to car

- Plazmaman intake pipe
- Pod filter
- Mbc
- Turbosmart wastgate actuator
- JDM coil packs
- High flow cat
- Ralliart muffler.

Please guys. Any help would be greatly appreciated.

evocrunch

Hows your engine compression?

iD33

Tuned? When removing the egr did you make adjustments in Evo Scan? Check the O2 sensor?

Addex

engine compression is a perfect 185 across the board. Extremely healthy engine.

We did find a lot of carbon build up. Not sure if that would affect anything?

Addex

Hi mate

Car is untuned. I wasn't aware I was supposed to make adjustments in evo scan Although the same issue has been there before I removed the egr. And still exactly the same after removing EGR.

what adjustments do I need to make?

I haven't checked the 02 sensor. Would that cause slow turbo spool and all the issues I listed above?

evocrunch

What about a boost leak test, have you done that? Seems like its a high possibility you have a leak somewhere in the system.

Addex

Ive done a boost leak test with a smoke machine and found small leak from the GFB bov. Would such a small leak cause all the issues I have been experiencing?

What would make the exhaust sound restricted and strained when coming onto boost?

DRAGHICI

iTrader: (2)

Is there an turbo exhaust flapper leak?

Addex

Ill have to check that out next!

4b11slayer

Boost leak test
Have you inspected turbo wheels?


Sounds like a boost leak honestly.

Any trouble codes in computer?

You need to do a real boost leak test with pressure.

4G63Rules

iTrader: (10)

What plugs are you using? What gap? Also, if you aren't tuned, most of your problems could be with that. Are you logging air/fuels? Do you have a wideband? I think you need to find a respectable tuner and get your car tuned. Your poor gas mileage is another factor regarding a tune. I would start there.

iD33

EGR: https://www.evolutionm.net/forums/ev...-canister.html

Boost leak test should be performed with pressurized air, your description, "restricted exhaust," sounds like a major boost leak. Check all intercooler pipes.

Do you know if the Evo is on a OEM factory tune? If it's on a custom tune you can re flash to OEM until a proper tune can be done with the current mods. Noticed you added parts, try putting back the stock intake and air box.

Addex

Thanks for the replies guys.

I have no idea why no mechanic in my city can do a proper boost leak test. They only have a smoke machine at 1 psi. I might have to buy or make my own boost leak tester.

I have tightened all intercooler clamps, I am not sure where the leak could be? Would I hear if the turbo to manifold gasket is leaking?

Spark plug gap is 0.7.

does anyone have a stock air box and snorkel for sale? Extremely hard to find one

I will also put the car on the dyno to see if the base map is still on there.

evocrunch

I wouldn't worry so much about your plugs if you aren't having a spark blow out. My bet would still be on a boost leak, it might very well be more than that small leak from your BOV.

Maybe try pulling open your intake piping and check for turbo shaft play as well? I think as one mentioned, the flapper could be a cause as well. Since you aren't holding boost or making the same amount of boost as before, I would place my attention on finding boost leaks. When you are making less boost as before, your exhaust would definitely feel more restrictive, as you now have less power.

I wouldn't bother about your tuning if you were running perfectly fine prior to this, unless you have changed a few parts that may affect tuning, and have not gotten a retune.

RightSaid fred

If it was completely standard, it should work properly.


Looking at the mods (usually the cause of most problems), the intake pipe isn't going to do a lot.
Pod filters are worse than stock.......get rid of it....both.
The MBC might be hooked up wrong giving WG boost.
As already mentioned, the WG flap might have no preload due to the actuator fitted wrongly.
The high flow cat might be low flow.


How about a video showing it idling and revving?


You haven't mentioned whether you bought it broken or if it broke after you did something to it.