Theory on fixing boost spike issues with cheap MBC's.

[forcefed86]

Seems lots of people are having issues with this. I did a search and the only solution I'm seeing is to buy a electronic boost controller or a aftermarket waste gate.

I'm having issues as well. I spike to 26psi and then settle back to 18-19. I'd like to set my boost to 25 but spiking to 30+ scares me.

Anyway I'll test this out tomorrow and see if it works.

Here's how I see it. (I may be wrong here, please fill me in if I'm mistaken)

So if spike is caused by the WG actuator not acting fast enough to open the WG. From what I can tell, this is because MBC's vent pressure so there isn't enough volume to actuate the WG quickly. So then boost spikes momentarily until enough volume passes through the MBC to open the gate all the way.

So I figure I can just plumb in a "boost can" before the MBC. Probably use a piece of 2" long PVC with 2 end caps. That way boost will fill the can first, then when the MBC cracks open it will have extra volume on tap to open the WG quickly.

Could also use a ton of vac line all coiled up as a vac storage as well.

Anyone think of a reason this won't work before a waste a day playing with it?

 

[1gDSM4g63]

Electronic boost controller is not the way to go. It's very unreliable holding high boost. Just get a good manual boost controller and run a boost leak check. By the way, why are you running stock injectors on and 255 lph pump?

 

[regulator213]

it can be several things..

A crap boost controller, your profile doesnt have it listed.

Vac line too long between Boost source and WGA (you should have a vac line from the nipple on the compressor side of the turbo going to your Boost controller then to your WGA, thats all. Keep it simple)

and possibly a bad tune as well.

I dont think that putting that "Boost Can" in will fix your problem. And if it does then you would just be covering up your problem not fixing it.

 

[pboglio]

Electronic unreliable in holding high boost? Never heard of that one. Manual boost controllers are all over the place with boost control, never had one worth a damned. Something is physically wrong with the setup if the turbo is spiking to 26 psi and leveling at 18-19 psi. I see this when the wastegate actuator rod is preloaded too much either with extra washers or the adjustable arm, nothing the boost controller can do to prevent it if that is how it was adjusted.

 

[forcefed86]

Well I made my own boost controller. Standard spring loaded ball valve. like so...
with a .020 bleed hole

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Actually I did a pressure test today. Found a small leak on my upipe weld and BOV. I repaired both of the leaks. Boost still spikes like crazy.

I just did all this recently. I'll update my profile. Now running 2gmaf, dsmchips stage 3 chip and 750cc injectors.

Before adding the 2gmaf, injectors, and chip the boost was steady at 17psi. No spike. Didn't change anything else. Car surges at idle now and boost spikes.

Heres the thread on that "issue"
http://www.dsmtuners.com/forums/bolt-tech/353599-2g-maf-w-750cc-injectors-causing-idle-surge.html

 

[Demon33]

Electronic boost controller is not the way to go. It's very unreliable holding high boost. Just get a good manual boost controller and run a boost leak check. By the way, why are you running stock injectors on and 255 lph pump?

What do you consider high boost?

With my Greddy Profec B-spec2 EBC I can tune the boost response to be hard, fast and overshoot the set point or tune to a response that ramps up quickly to the set point but doesn't overshoot, all from within the cab in only seconds. I don't know of any manual boost controller that allows you to adjust the boost curve this easily and with this much control.

I currently run my e316g at 25psi on a daily basis and my EBC never overshoots and holds boost solidly to redline, as verified by my Greddy peak hold electronic boost gauge and logger.

 

[1gDSM4g63]

I had a Profec B-spec II which cannot handle 28psi+ and the Apexi AVC-R doesn't do much better so unless the OP is willing to spend over a $1000 for the HKS EVC Pro which can do 36 psi I'd much rather prefer a Hallman for $100 that could handle 50psi+.

 

[Demon33]

I had a Profec B-spec II which cannot handle 28psi+ and the Apexi AVC-R doesn't do much better so unless the OP is willing to spend over a $1000 for the HKS EVC Pro which can do 36 psi I'd much rather prefer a Hallman for $100 that could handle 50psi+.

Seems lots of people are having issues with this. I did a search and the only solution I'm seeing is to buy a electronic boost controller or a aftermarket waste gate.

I'm having issues as well. I spike to 26psi and then settle back to 18-19. I'd like to set my boost to 25 but spiking to 30+ scares me.

I've never ran more than 25psi so I can't comment on an EBCs effectiveness at that boost level. I'll have to take your word on running it at 28+psi. However, the OP only wants to set boost at 25psi which I have been running in my daily driver for some time now using an EBC without issue. Based on my experience with the Greddy Profec B-spec2, I highly recommend it for boost levels of 25psi or less for its ease of tuning, the ability to change the boost response curve and for the rock solid control. Again, this is from my experience with the boost controller, turbo (e316g) and the setup I have running at 25psi. Your results may vary.
Good luck.

 

[1gDSM4g63]

Well, I have to admit that I was once all into the electronic boost control all spiffy looking with high/low boost functions, but it's a b!tch to set that up. And even though Greddy Profec boost is one of the best out there I moved on from that.

Overall I have no objections to an electronic boost controller, but with your methanol injection and an upgrade in fuel injectors it will hold you back. Make it easy for yourself and go with a cheaper manual boost controller.

 

[forcefed86]

Don't know how this became a electronic VS manual boost control thread but lets get back on track.

I hooked my WG up directly and I get a rock solid 9psi. So it is the MBC. This looks like a very easy and in expensive boost control that will not spike. Could be easily made for under 25 bucks. I'll probably place it in a small sheet metal or ABS box and mount it by the air cleaner.



Here it is copied from dodge garage.

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When no voltage is applied to the solenoid, boost pressure runs directly to the wastegate.

This will leave you with 6-14 lbs of boost depending on load, rpm, throttle and how well your head/exhaust systems flow.

At normal rpms I see about 7 psi, at 5500rpm in 3rd or 4th gear boost will rise as high as 14psi (WOT)! This is due to a very high flowing exhaust system (3 inch, no cat, non-baffled muffler).

Now when 12 volts is applied to the solenoid, it creates a bleed to the wastegate, and in my case results in 18 psi of boost.

Here's the tricky part- when boost pressure rises higher than 18 psi, the pressure switch removes the ground path for the solenoid causing the wastegate to get full intake pressure and the boost drops off.

As soon as the boost drops below 18 psi, the solenoid come back on and boost resumes again.
This happens so fast it appears as a slight flutter once or twice in the gauge at max boost if you have done your job correctly.

Some trial and error maybe required to get your boost "just so" but this is a very safe system if the pressure switch is set to the max boost your engine can safely run.

 

[AWD92TalonTSi]

Do you show any knock counts when it spikes?
Maybe try a different spring or ball; maybe one of them is hanging up causing excess pressure to actuate.

 

[josh38127]

I am still just stock. I am waiting on my Autometer Boost gauge to get here. I was wondering bout a few MBC I saw on this sites online store all I is about 12-15lbs. I like the one for 19.99. by Concept Illusions.

Forgive the Noob question.. What does WOT mean

sorry for jacking your tread man

 

[AWD92TalonTSi]

Forgive the Noob question.. What does WOT mean

Putting the hammer down
Flooring it


or Wide Open Throttle

McMaster-Carr

I used that and drilled/tapped the non threaded end for 1/8" npt and drilled a 1/32" hole in it to make my boost controller. It overshoots by 2-3 psi but I don't get any knock counts so I don't worry about it.

Bryan