20+ psi uncontrolled boost! Intake pipe, 2G mas, catch can add-on, now blown HG!

[cjhanas]

Okay, so I know this swap didn't go smoothly, but I'd like to figure out why my boost control is out of control before I go blowing another Head Gasket like I did this afternoon...

Here's the skinny.

Pulled my 1g mas/intake out, installed 2g mas w/3" pipe (no vacuum nipples). Rewired correctly. Bent wastgate nipple (ever-so-slightly with a wire hanger inside as to not collapse nipple) to clear 3"intake. Started up, idled great, ran great on and off boost, no boost control though with MBC turned all the way down. Here's what I don't know.

When it comes down to the catch can install, I had to re-route the vacuum lines. So the vacuum line running from the valvecover to the intake is now routed from the valve cover to the catch can. The other side of the catch can had a breather filter installed. The line that looks to be running to a vacuum canister was plugged.

After doing some searching, I have found that it's advisable to NOT to T into the BOV line, but this is more preference than proof. This is my current setup, and has always worked fine and reliable.

However, after seeing the first pull, my boost gauge shot way past my 20 psi mark (the limit on my gauge). Doing several pulls at midnight with cool air and no knock this didn't seem to be too bad or too great. No difference in pull between 18psi and 24 psi.

TODAY, I take off the breather filter, and run the plugged line (to the vacuum canister) to the catch can to complete the loop per-say. Do another run to see if this has changed anything and upon laying on the bost slowly in 3rd as I reach 20 psi, I find all of the sudden a HUGE puff of white smoke out my exhaust. Right then I knew I blem something. Pull over to find oil flooding out the #1 runner's exhaust and EGT bung, and no coolant in the overflow bottle. Right then I knew my head gasket was blown, possibly my 16g as well but not as concerned about that right now.

My question is now, why and how is my boost suddenly uncontrolled? What did I change if anything in the way my MBC works? I will try to un T my BOV line next...

Should I not drive the car to full boost afterward? I need to fix this problem BEFORE the new HG goes in...

Many thanks in advance.

 

[red_devil]

I will try to un T my BOV line next...QUOTE]

I have heard many people having problems by doing this so I would try that. Also you have an EVOIII they love to run at 20psi

 

[lccynmbr13]

Boost creep...

 

[cjhanas]

Actually no, creep is not an issue for me. I just lost ALL my boost control once i re-routed some vacuum lines. I have NO idea why this hapened, as vacuum doesn't really need a start or finish, just a complete cycle, right?

red devil, I will try hooking up my MBC differently, and keep you posted on the result ass of tomorrow.

BUT ONCE AGAIN, does anyone have ANY idea as to why this happened. I had PERFECT boost control before the catch can mod and different routing of vacuum lines...

Thanks for the help guys

 

[Talesin]

Given that you went off the chart as it were, I'd say you were running uncontrolled the whole time, just the ECU was able to retard timing fast enough to prevent detonation.

The line from the VC to the intake is a vent line, to allow any blow-by somewhere to go. Not part of the vacuum system.

I have no idea what you mean by 'vacuum canister'... the only thing I can imagine is the charcoal evap cannister, which is supposed to (needs to) feed into the intake so that when you are over a certain RPM level, the evap solenoid opens and feeds the fuel vapors trapped in the cannister into the intake to help richen things up.

Judging from the somewhat vague descriptions, I can only assume that you hooked your evap into the catch can, so the vapors went there instead (if they went anywhere at all, with no real vacuum to pull them out). I'd guess that less likely, the fuel vapors ended up in your crankcase and spontaneously ignited due to the latent heat.
Or more likely, that extra fuel from the evap just wasn't there, and compounded the uncontrolled boost, over-leaning the mixture further than the ECU could possibly deal with, and you detonated.

Did you set the SAFC to compensate for the 2G MAS? It runs a LOT leaner than the 1G in stock form, so that'd definitely contribute if you didn't, again especially with uncontrolled boost.

Stock pressure on that wastegate actuator should be right around 10psi. You should NOT be spiking to 20 if it's working correctly. Also, might be a good idea to get a standard 30/30 boost/vac gauge, instead of the 20. NEVER just romp on it if your boost shoots off the chart, you'll blow something.
As for the BOV teeing debate, I've put in my two cents on a number of threads, and feel that it is a bad idea, which will shorten turbo lifespan and contribute to boost spike.


Short version, my guess would be that you over-leaned the living **** out of it, and detonated. But get the wastegate checked out before you go boosting off again, in any case.

 

[cjhanas]

Talesin, thanks for the long in-depth response. You did clarify some of my vacuum concerns. I think you are correct about the whole evap canister, and not a vacuum canister. I just assumed it was an extended source of vacuum, kinda like a jeep.

Today was interesting. I pluged the evap-canister line like I had before, put the breather filter back on, and un-T'ed the BOV line to run a direct connct from the compressor outlet to the MBC to the wastegate. Boost was more controlled, but still not set at 1 bar like the actuator spring. I was able to spike up to 19 or so, and slowly come back down. Funny thing too; no white smoke, no signs of poor operation. Everything seemed to work flawlessly.

My Ecu has been chipped with compensation for my bigger injectors and the 2g mas. Since I'm still running the stock IC (I know I know) I pushed the table on the hi side up about 20% at 7k and decreasing gradually from there as revs drop.
Don't think I'm lean, if anything too rich.

Don't know how much in-out shaft play is normal, but i surely have a bit more than I started with a month ago. I'd say about 1/8" or so. I'm assuming the turbo's still good to go. Will be yanking the head during the next week...

Thanks again fellas, this site is great.

 

[Talesin]

Nope, the evap is where all the fumes from your gas tank go and collect when the fuel evaporates. :3

Okay, are you talking about the MBC actuator spring, or an adjustable wastegate actuator along with the MBC? On a ball-and-spring MBC, any pressure level marks really aren't reliable.. you just need to do pulls and tighten or loosen the adjusting bit until your boost gauge shows the proper peak desired. If you have an adjustable wastegate... why do you have the MBC on?! The stock wastegate actuator is 10psi, not 1BAR (14.7psi) if that's what you'd meant. Try taking the MBC out of the loop entirely, just run a vacuum line (real short one) from the compressor housing vac fitting to the wastegate. That'll verify proper operation for the WG, before you add the MBC into the mix.
You'll make more power on less boost, with a better tune. Talked with a guy who was about to buy an Evo, who couldn't figure out why his car-to-be felt so slow, when he was boosting at 25psi. He was running with the ball-and-spring MBC installed backward... no boost reference to the wastegate, so it was just staying closed and overboosting like crazy. Knock, pulled timing, slow car. Reversed the lines, and he was a LOT happier with how hard it pulled after that.

From the way you'd written it, sounded like you just pulled your 1G MAS/intake and plugged in the 2G units, possibly without swapping out the EPROM at the same time.

Before you yank the head, run a compression test, and possibly a leakdown. Could be something as small as a blown valve seal on the exhaust side... which you still have to remove the head to replace, but hey, at least you'll know where to look for potential problems.

 

[cjhanas]

Got the talon back on the road finally. THanks to ARP, Cosmetic, and me. Now the the head's taken care of, I blew the turbo bearings on my evo turbo. Go figure...

The boost control was horrible with it was T'ed from the BOV. Comes to show how a turbo that wants to pull will easily spike if T'ed off... Starange how it did real well that way for a while. Thanks for all the help fellas. Anyone got an evo turbo their looking to pawn?