Overboost on evo3 big 16g install

[flosho]

Last summer we installed a evo 3 big 16 g and then had to put it away for storage, now its overboosting like crazy.

First, no boost controller at all.

I have it set up so that theres a vac line from the pressure side of the turbo to the wastegate, and then have a T in there to run to the stock boost solenoid, the top line from the boost solenoid is the one that tee's into the line from the wg to turbo. The bottom vac line from the boost solenoid goes to the intake after the maf.

It as has a ebay knockoff BOV rerouted.. but the vac line from the intake manifold goes to the top vacuum nipple on the bov.

Is this all hooked up right? or should I not tee in the stock boost controll solenoid?

thanks
Jason

 

[DSMunknown]

Last summer we installed a evo 3 big 16 g and then had to put it away for storage, now its overboosting like crazy.

First, no boost controller at all.

I have it set up so that theres a vac line from the pressure side of the turbo to the wastegate, and then have a T in there to run to the stock boost solenoid, the top line from the boost solenoid is the one that tee's into the line from the wg to turbo. The bottom vac line from the boost solenoid goes to the intake after the maf.

It as has a ebay knockoff BOV rerouted.. but the vac line from the intake manifold goes to the top vacuum nipple on the bov.

Is this all hooked up right? or should I not tee in the stock boost controll solenoid?

thanks
Jason

Hmmmm, I wonder why you are experiencing boost fluctuations....



Jason, get yourself a proven or adequate MBC or EBC. You can use brute's guide for assistance. Then come back and post if you have further issues with overboosting. The factory BCS doesn't do much in regards of controlling the amount of boost the turbo wants to make. It's a piece of garbage, so you shouldn't trust it with the money you've invested.

You can pick up an MBC for as cheap as 40 bucks. Do yourself and your car a favor and purchase one pronto.

 

[flosho]

eek.. so there's no way to control the boost on it w/o actually having some type of boost controller?

If so, I have a few extras layin' 'round.

 

[DSMunknown]

eek.. so there's no way to control the boost on it w/o actually having some type of boost controller?

If so, I have a few extras layin' 'round.

That's why it's called a boost controller, because it aids in controlling the amount of boost.



It's also why people/manufacturers utilize wastegates.

 

[oldman]

My money is on boost creep, describe "boosting like crazy" in detail.

 

[DSMunknown]

Oh, and it would be great if you could follow the instructions in this link, just like the rest of us have.




Completely filling out the necessary boxes helps us help you.

 

[flosho]

That's why it's called a boost controller, because it aids in controlling the amount of boost.



It's also why people/manufacturers utilize wastegates.

I know what a boost controller does and I know why turbos have wastegates. I figured that the wastegate would be preset to something like 1 bar of pressure to prevent overboosting. So that if you installed the turbo in the car, you wouldn't NEED a boost controller to control the boost, hence my question about the stock bcs..

I have a mbc installed on my car, and I'm not as familiar with dsm's as I am my car, so please forgive me.

Anyways, I've installed a mbc that I had around here, per brute's instructions.

My money is on boost creep, describe "boosting like crazy" in detail.

Well under 3/4 throttle it'll spool up to 17+ psi and doesn't max out at any point. I'm hesitant to go WOT because theres no point where the boost stops and then slowly crawls up, its just one steady sweep to 17+ which is where I usually let off.. I'm not interested in doing a rebuild.

Also its a 98 auto gsx eclipse.

And I do appreciate the help but unless the MBC I have isn't working properly, I still think there's something I'm missing.

 

[romeen]

Jason, does the boost continue to climb after you let off the gas or does it shoot uncontrollably up only while accelerating? As Bruce mentioned, be more specific about what it is doing.

In the meantime try running a vacuum line from the boost/pressure source directly to the nipple on the WGA without any tees to other components. That nipple on the WGA is pretty small so make sure your using the appropriate size hose and secure it with a zip tie or small clamp. Let us know how this effects boost levels.

Please fill out your vehicle profile so we can better help you.

 

[flosho]

Jason, does the boost continue to climb after you let off the gas or does it shoot uncontrollably up only while accelerating? As Bruce mentioned, be more specific about what it is doing.

In the meantime try running a vacuum line from the boost/pressure source directly to the nipple on the WGA without any tees to other components. That nipple on the WGA is pretty small so make sure your using the appropriate size hose and secure it with a zip tie or small clamp. Let us know how this effects boost levels.

Please fill out your vehicle profile so we can better help you.

After I let off the gas, it goes back to vacuum, but under any "harder" acceleration(such as more than 1/2 throttle, where I actually get into the 3500+RPM range) it spools steady past 15, and I usually let off around 17-20psi, like I said, I'm afraid to hold it out any further.

Also I do have the mbc set to the "lowest" setting, meaning the adjustment screw is backed out almost completely.

I'll try the direct line from compressor nipple to wga nipple. That's what I was asking about before(and was told I need a MBC), to see what the stock setting is on the wastegate.. Its a evo3 big16g. Stock exhaust...


Also, should I leave the line from the stock BCS into the rubber intake pipe, or just cap the nipple on the rubber intake off?

 

[romeen]

So if I am understanding correctly you installed a mbc since your first post, right? If so did this change anything compared to before? Also what type of mbc is it?

Since you have a stock exhaust it is unlikely that it is boost creep. So the unusual routing of those vacuum lines is/was probably causing a boost spike. If you have a mbc hooked inline between compresor and WGA then you can ignore the BCS. Leave the electrical harness plugged into it to avoid a CEL but you can leave the nipples exposed, it won't make any difference.

I haven't looked at a stock intake pipe for awhile but as I remember the hose going to the larger nipple on it is from the charcoal canister located under the battery. The smaller nipple should be connected to the nipple on the passenger side of the valve cover.

You may want to go ahead and bypass the mbc as I originally suggested just to see what happens. This will help to narrow down and troubleshoot possible causes. Try it and let us know how it works.

 

[flosho]

So if I am understanding correctly you installed a mbc since your first post, right? If so did this change anything compared to before? Also what type of mbc is it?

Since you have a stock exhaust it is unlikely that it is boost creep. So the unusual routing of those vacuum lines is/was probably causing a boost spike. If you have a mbc hooked inline between compresor and WGA then you can ignore the BCS. Leave the electrical harness plugged into it to avoid a CEL but you can leave the nipples exposed, it won't make any difference.

I haven't looked at a stock intake pipe for awhile but as I remember the hose going to the larger nipple on it is from the charcoal canister located under the battery. The smaller nipple should be connected to the nipple on the passenger side of the valve cover.

You may want to go ahead and bypass the mbc as I originally suggested just to see what happens. This will help to narrow down and troubleshoot possible causes. Try it and let us know how it works.

Yes you are correct, I have since(the first post) installed a manual boost controller in between the WGA and compressor nipple. The result is the same, overboost. However, the manual boost controller I used is about 2 years old, and a generic $7 off ebay. I have a very similar one installed on my other car and it works perfect. I will probably buy a new one.

Tomorrow I will bypass the MBC all together and run straight pressure source to WGA and see what happens. Does anyone know what the WG is set at?

The only other thing I can think of is that the nipple on the compressor side isn't tapped all the way or something, I didn't inspect it that closely before the turbo was installed. If the straight shot attempt doesn't work, I'll tee off the BOV vacuum line and see if that works.

Thanks guys
Jason

 

[oldman]

Never Tee off the BOV line!!!

 

[flosho]

Ok, continued my searching, and came up with this thread, which seems to be the same problem...

http://www.dsmtuners.com/forums/showthread.php?t=234612&highlight=EvoIII+16g+stock+boost

Tomorrow if I have time I'll tackle some of the suggestions in that thread.

 

[oldman]

Jason, you're making this more complicated than it needs to be, test run with the MBC/BCS bypassed. If problem persists, your actuator/wastegate is stuck closed. If problem solved, it's your mbc/bcs. If you suspect the turbo fitting was not tapped all the way through, blow into the vacuum line connected to it.

 

[kenamond]

Also, when you disconnected the BCS, did you cap the nipple on the bottom of the intake pipe? If not, you're probably sucking unmetered air in through that nipple and running a tad lean, moreso under boost.

 

[flosho]

Jason, you're making this more complicated than it needs to be, test run with the MBC/BCS bypassed. If problem persists, your actuator/wastegate is stuck closed. If problem solved, it's your mbc/bcs. If you suspect the turbo fitting was not tapped all the way through, blow into the vacuum line connected to it.

, i was just doing some more searching, I ended up going back outside last nite and running the vacuum directly and it solved the over boost problem, it would hit ~12 psi and then creep up a bit towards redline.. but its not out of control..

Also, when you disconnected the BCS, did you cap the nipple on the bottom of the intake pipe? If not, you're probably sucking unmetered air in through that nipple and running a tad lean, moreso under boost.

I just left the vacuum line hooked up to the intake and bcs, so it should be fine..

Now just have to get a decent boost controller.

 

[oldman]

I just left the vacuum line hooked up to the intake and bcs, so it should be fine..

It will still allow air to enter the intake pipe though not much, I would just cap off the fitting. Glad you got your problem resolved, I was right about boost creep all along.

Which MBC was it? Ball and spring? Take it apart and tell us what you see, you may be able to fix it.

 

[flosho]

It will still allow air to enter the intake pipe though not much, I would just cap off the fitting. Glad you got your problem resolved, I was right about boost creep all along.

Which MBC was it? Ball and spring? Take it apart and tell us what you see, you may be able to fix it.

I'll cap it off today, but I was just using headlights from my other car light.. I just had to try to fix it.

It is creeping a bit, but it was definatley not opening the wastegate at all before.


The MBC is just a ball and spring, but the spring seems a little small. Just seems a little finicky.. oh well I'll get a new one.

 

[oldman]

The MBC is just a ball and spring, but the spring seems a little small. Just seems a little finicky.. oh well I'll get a new one.

Try shortening the spring.

 

[flosho]

Try shortening the spring.

That what I mean, the spring is already pretty short that I have to have the adjustment screw in nearly half way before the screw is touching the spring.

 

[oldman]

That what I mean, the spring is already pretty short that I have to have the adjustment screw in nearly half way before the screw is touching the spring.

Then either the wastegate pressure relief hole is too big or the body is leaking causing pressure drop on the pressure signal going to the wastegate. Home Depot MBC?

 

[RipperXX]

May I recomend a Joe P

 

[flosho]

Got a new manual boost controller and installed it. It's still doing the same thing. Even with the boost controller set as low as it will go, it still boost uncontrollably. I emailed turbochargers.com and they said the wastegate should default to 9-11 psi.. So I re-hooked up the pressure side nipple directly to the wastegate, and it still boost 15+ before I let off.

So there has to be something wrong with the wastegate or wastegate actuator, because it definately isn't opening correctly.

Question: under what conditions does the fuel cut come into play? WOT only? What PSI?

Any more suggestions?

 

[oldman]

Clear this up for us as your post is kinda confusing, last time when you bypassed the old MBC by connecting the fitting on your J-pipe directly to the wastegate actuator, you got 11-12psi then creeps up a little. This time after you bypassed the new MBC (which MBC and how is it hooked up in respect to the fittings on the MBC as well as direction of adjustment, some MBCs are reversed), boost shot straight past 15psi without pausing at 11-12psi, is this correct?

 

[flosho]

haha.. that is correct. It worked for an afternoon, then it started to boost higher again. I hooked it up directly this after noon and it still boosts too high. I hook the MBC up and it boost high still, only faster.

Also, I'm thinking the timing may be off, because it has hit 18-20 PSI and there is no fuel cut. Reading through the vfaq, the timing may be retarded/out of time.