I have 2g gst.

I am getting some pretty bad turbo lag. The freshly rebuilt EvoII Big 16g is spooling maybe 10psi at 3500 rpm and doesnt hit full boost till 6000 rpm. And this is with the wastegate disabled, I should be getting at least 30+psi in this situation.

mods:

-low milage jdm engine
-front mount
-big 16g
-780cc injectors
-Ecmlink
-3inch exhaust
-wide band o2
-Afpr

Things I have already checked:

-Boost leak test, I found a bunch and fixed them all, except the slow leaks at the injector seals and throttle body shafts (could these leaks cause really bad lag like this?)

-exhaust gaskets preturbo replaced and torqued bolts to spec

-Timing marks on engine line up correctly
-Turbo has zero shaft play, flapper covers hole in exhaust housing completely


I posted a log and am wondering if this crazy lag is the cause of a really bad tune? I have changed nothing with the tune since i bought the car. Except I changed the dead time a little to try and get fuel trims.

basically could this lag be "tuned out with timing and fuel" or is the rebuild on the turbo be crap or what?

thanks in advance I have been reading and checking everything I could find for weeks and all that is left really is the tune... I posted a log.

It's a mechanical issue... not tuning.

My guess is that either your WG is blowing open (leaking diaphragm maybe?), your boost controller (?) isn't functioning properly or is leaking, or those boost leaks aren't as small as you think.

When doing the BLT, how much pressure can you hold and for how long?

I don't see any boost or wideband data in your log. It's really hard to tell what's going on (much less tune) without at least one of those; in this case we really need to see your boost curve.

EDIT:

Wait... you say the WG is "disabled"? How did you disable it, and what did you do with the flapper on the turbo?

calan said:

It's a mechanical issue... not tuning.

My guess is that either your WG is blowing open (leaking diaphragm maybe?), your boost controller (?) isn't functioning properly or is leaking, or those boost leaks aren't as small as you think.

When doing the BLT, how much pressure can you hold and for how long?

I don't see any boost or wideband data in your log. It's really hard to tell what's going on (much less tune) without at least one of those; in this case we really need to see your boost curve.

EDIT:

Wait... you say the WG is "disabled"? How did you disable it, and what did you do with the flapper on the turbo?

Click to expand...

I disabled the wastegate by plugging the line to the wastegate acuator to allow "full boost potential"....
also how do I put boost and wide band data in my log?
Also when doing the BLT I can not build more than 22psi and I have my air compressor set to 30psi... where should I have the enigne set at TDC cause it was not set any where specific and a lot of air was moving through the crank vent on the valve cover.

I very much appreciate all your help in this and I will try a 1g blow off valve and replacing the throttle body shaft seals

You need a new PCV and you should supplement it with a US plastics valve. That will fix all the air shooting out of your crankcase ventilation.

Check Valves | U.S. Plastic Corp. 3/8 seems to be the consensus size. You really only need either the check valve or the PCV but neither are expensive and doing both doesn't hurt.

I disabled the wastegate by plugging the line to the wastegate acuator to allow "full boost potential"....

Click to expand...

I'm not quite sure where you got this from. In order to disable boost control you simply remove the vacuum line entirely from the wastegate canister (the gold or silver can hanging off the turbo) you won't need to block it or anything there. You do need to block the vacuum hose connections that you remove to avoid boost leaks but otherwise this is all you need. From the sounds of it you have already effectively done this. This leads to a few options for what might be wrong.

The first option would be that your wastegate arm has come loose from the wastegate flapper, check to make sure that the arm is attached to something.

The second option is that you have a cracked o2 housing or major exhaust leak allowing massive exit of exhaust before the turbine. This could be checked by running a can of seafoam through the engine. When seafoam is allowed into the engine through a vacuum line and burned it causes smoky exhaust which will immediately show any exhaust leaks.

The third option is that your turbo is dying/dead. This would suck but it is a possibility.

Those are the most likely options so I'd start there and report back.

the_mork said:

You need a new PCV and you should supplement it with a US plastics valve. That will fix all the air shooting out of your crankcase ventilation..

Click to expand...

I ordered one of these for all three of my mitsubishi turbo cars thanks, but I did another BLT and plugged the PVC line to eliminate this from my BLT air still is flowing out the oil fill hole could this be because I did the BLT test with the engine cold? I also found a boost leak at the EGR valve block off plate, I replaced the gasket there .

the_mork said:

The first option would be that your wastegate arm has come loose from the wastegate flapper, check to make sure that the arm is attached to something..

Click to expand...

I have already ensured that, but I just shimmed the wastegate acuator so I am gonna go do a test drive now.

the_mork said:

The second option is that you have a cracked o2 housing or major exhaust leak allowing massive exit of exhaust before the turbine. This could be checked by running a can of seafoam through the engine. When seafoam is allowed into the engine through a vacuum line and burned it causes smoky exhaust which will immediately show any exhaust leaks.

Click to expand...

I am gonna go try the sea foam right now as well but I have already pulled the turbo to inspect for cracks and shaft play and the wastegate flapper sealing properly all looks good and I installed a new manifold gasket on the reinstall along with permatex copper gasket spray.

the_mork said:

The third option is that your turbo is dying/dead. This would suck but it is a possibility.

Click to expand...

I was told by the guy that I bought the car from on here that it was rebuilt by justin and the compressor wheel is signed with a J61 not sure what that means but it spins very nice better even than my brand new evo316g on my talon, so I hope its not the turbo but i would prefer that of bad rings/ and or compression in engine


Thanks for all the help I am going out right now to do the seafoam and see if the shim helped
thanks again

could the injector compensation or dead time be off enough to cause a lot of turbo lag??

Okay so shiming the wastegate did nothing, but the sea foam revealed that the gasket between the turbo and the manifold is leaking pretty badly! Also some smoke was coming out of the turbine housing where the wastegate flapper arm comes through it. I am not sure what could be done about this or if it is normal or if this would cause slow spool..., but the preturbo leak IMHO was and is really bad I will be replaceing this gasket tomorrow and report back...

I replaced the gasket between the turbo and exhaust manifold and it still is slow to boost. I did another sea foam test and get smoke out the turbine housing flapper arm to the internal wastegate and out the vertical line that looks like it was made in the casting I guess it is cracked hairline along this as smoke is coming out I quess I need to get a new turbine housing... Would this cause slow spool?

How bad is the leak? If it is pouring out then possibly, and if it is only a small bit then it wont cause much of a change in spooling behavior.

Poor tuning can affect spool, but not nearly this significantly without causing more noticeable problems otherwise.

Generally air coming out of the oil cap during a BLT isn't positive. How much of a boost leak are we talking about? A small leak wont doesn't necessarily mean much of an issue but can definitely suggest bad valve seals.


Does the car run fine otherwise?

As for the turbine housing leak I've heard tell that it is very very rare for a true evo3 turbine housing to crack


What is your tune like anyway? How far off are your fuel trims?

I don't have access to my laptop right now but how does your timing look from idle to around 3 grand? If it's really low like the factory setting (0 degrees of timing while under the boost curve.) It's probably not a timing issue but, some dsmers like to turn the timing up as if the car didn't have a turbo. (A natural aspirated type timing curve) I tried this before and it really wakes the car up but the full boost rpm increased quite a bit.

Check your timing tables and compare it with the stock timing map. I hope this helps... Corey

I swapped out my turbine housing with a known good one, I saw a very slight increase in max boost and spool was ever so slightly better, but it still spools too slow, I did another boost leak test and I have a good bit of air coming out the valve cover vent

(it feels like the amount of air like if you were to exhale normally, while whistling...)

and if I put my finger over the hole it will build a lot of pressure in there and when I pull my finger off the vent a huge amount of air comes out...

I did this boost test right at the throttle body as to not include the turbo in the test I also did the test at the turbo same result just took longer to pressurize the whole sytem

could leaking valve seals on the intake side allow this boost into the crank case??

I am at a loss!!!!!!!!

Either that or piston rings leaking boost into the crankcase. Do a compression test.

fallenauthority said:

Either that or piston rings leaking boost into the crankcase. Do a compression test.

Click to expand...

if the compression test comes back "good" would it be the valve seals and if so can they be change on the car or do I have to pull the head?

Would leaking piston rings cause slow spool?

also the other symptom I am having is very poor gas mileage.

Can a turbo have zero shaft play and no smoke that I have ever noticed but still spool like a piece of garbage

a91talonAWD said:

if the compression test comes back "good" would it be the valve seals and if so can they be change on the car or do I have to pull the head?

Would leaking piston rings cause slow spool?

also the other symptom I am having is very poor gas mileage.

Can a turbo have zero shaft play and no smoke that I have ever noticed but still spool like a piece of garbage

Click to expand...

Youj could have leaky stem seals but you shouldve noticed it burning oil at idle and at startup. And those won't cause low compression, just burning oil.
Rings leaking compression could cause slow spool if one or more of them were REALLY bad. I mean the car would run terrible, no power at all.
I am doubting something is wrong with the turbo if you dont have shaft play and it is not burning oil or making terrible noise.

Possible clogged cat. There are only a couple things that cause a good turbo to have horrible lag, and low boost. Very low deltaP across the turbine(either a leak before, or restriction after), and very large boost leaks.

have you tried turning the turbo by hand with your fingers? or if you are idling with and shut the car off and look at the turbo is it stil spinning?(leave MAF pipe loose for this simple test) I've seen turbos that are coked up from burnt oil that are stiff to turn with your fingers and also would have completely stopped spining a soon as the engine was stopped or wouldn't even spin at idle, those are all signs of turbo problems, coking, bent shaft etc..

a91talonAWD said:

I did another boost leak test and I have a good bit of air coming out the valve cover vent

Click to expand...

Try sealing the intake manifold off from the PCV, make sure all vac lines off the mani are good or are pinched off and then repeat the test.

If you still have a lot of air escaping via the valve cover, then it's most likely either valve seals or fried rings. As much air as you're describing is a fairly big issue though and I'd be much more suspicious of that amount of air getting out by crossing directly into the valve cover than by slipping out past the valve seals or even less likely, the piston rings.



You may also have multiple issues compounding this problem. Granted, I haven't looked at your log and since there's no wideband data included, I don't think it will help me find anything anyway. But, if your tune is and has been excessively rich for long enough you could be looking at a lot of problems here.

Running too rich for too long can:

• wash out rings (resulting in very low effective compression),
• overheat a turbine housing with still burning fuel (causing housing cracks & melted turbine blades),
• fuel soak and melt a catalytic converter (causing a low pressure differential -as donnie noted-, higher engine back pressure, and more frequently blown hot side gaskets),
• can clog a PCV valve quickly
• and it also burns cooler and creates less exhaust pressure.

All of these factors will put less exhaust energy into driving the turbine.
But I still suspect the problem is somewhere between the intake mani and the valve cover.

warm engine compression results were (dry test)

163-165-165-166

So if this air coming out my valve cover is the valve seals would this be enough to cause slow spool?

Also when I spin the turbo it spins very very freely almost too freely, could this be a sign of blown or fried turbo seals? If I spin it by hand it makes about three full revolutions before coming to a stop...

I have an Evo316g in my talon as well and it doesnt spin for nearly as long as this one does and it is a low mileage MHI turbo