18g spike problems.

[sqr]

Edit 10-14-11, this is really an ebc problem. The boost is just to choppy for my tuning ststem.

I am running a td05h 18g 15* clip. I get a big spike if i run a mbc. My Profect B spec 2 helps a lot, but the boost trace on the data logs still looks like a rip saw blade with 1.5 to 2 psi variances till the boost and or air flow is real high.

I can feel and hear the power fluctuation as the waste gate cycles and it screws with my neo afc tune.


Any tips on waste gate preload or limiting the arm length ect to minimize the problem? I also have a Gizmo ebc, would that be better?

Currently running about 22 psi. I have run as much as 25-26 before the clipping.

The turbo is on a 300 hp Conquest in a 8cm conquest exhaust housing. 06 compressor cover.


How high can i boost this turbo and get reasonable life and not risk instant turbo failure?

Lots of?'s, Thank for your input.

 

[JusMX141]

Like, spikes at the onset of boost then gains control, spikes / settles / spikes / settles the entire time you're in boost, or creeps out of control from the get-go? I'm having a difficult time understanding what's going on...and all three situations I described have a different solution.

 

[sqr]

"spikes / settles / spikes / settles "

Fridays track run, using the ebc. The problem is worse at lower boost and rpm on the street.

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Typical boost trace with a mbc, 05h unclipped at the time.

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[JusMX141]

That's generally the result of a faulty boost controller, perhaps a torn wastegate actuator diaphragm (takes a spike to overcome the amount of air leaking out, which opens the gate- then the gate slams shut once enough pressure leaks to where it cannot stay open anymore), or just a bad boost source in general.

Where are you sourcing your boost pressure for the actuator? It should be on it's own dedicated line near the compressor cover and not tee'd into the BOV line.

 

[sqr]

The solenoid/actuator boost source is a dedicated line after the intercooler and before the throttle body. The greedy boost sensor is after the throttle body.

I will move the solenoid/actuator boost source to the compressor cover.

 

[JusMX141]

The only thing I can tell you is that if it's still an issue once you get the boost source on it's own dedicated line, try eliminating your boost controllers altogether and just run a line straight to the actuator. If the problem goes away entirely, start back with the boost controllers and turn the boost up slowly until it starts to go all over the place again, and report back here. If the problem persists, you need a new actuator.

 

[NOSLO2PT0]

MBC's will always produce a spike of sorts. Just the nature of the beast. An EBC will control that spike a little better.

 

[sqr]

Moving the ebc solenoid to the compressor cover helped a little at part throttle, but not at wot.

Put a turbo xs mbc on sourced at the compressor cover. Nice and smooth but less response and tails off. 24.23 peak, drops to 22, than tails off to 19.5 I did not pressure check the actuator yet.

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[NOSLO2PT0]

Use a boost source somewhere off the intake manifold to get a true reading of actual boost. Taking a reading off the compressor cover gives you slightly higher #'s as you don't account for pressure drop across the intercooler. Use the EBC, source it off the intake manifold, and post results.

 

[JusMX141]

I always source MBC's near the cover for the quickest response. It will still produce the same boost pressure result if your gauge pressure is sourced at the manifold. In other words, if the turbo is making 25psi but you're only seeing 22psi at the manifold, the wastegate is still going to control it so you see a consistent 22psi or whatever.

Not sure how this works on certain EBC's, however.

 

[NOSLO2PT0]

I haven't run an MBC since about 2003. When I did....I would see a 3-4psi spike regardless of where I sourced it. As soon as I switched to an EBC, never saw another spike. I went from using a Greddy Profec B to an HKS EVC EZ. Both produced rock solid boost levels, and never spiked one bit.

 

[sqr]

Although i did have an initial spike problems with this 18g turbo in the past, i think the clip helped with that.

I realize now this is really a choppy boost with a ebc problem, and as such the thread is tittled wrong.

The boost was also choppy with a 17c and 19c turbo as well. The difference is those turbo were done at 22-24 psi and it would smooth out.

My data logger is plumbed to the intake as is the ebc sensor. Ebc sensor is plumbed in to the blow off valve hose. I am going to run a dedicated line. I am also re doing a sloppy hole in the waste gate actuator arm at the flapper pivot.

Others have complained of choppy boost with a profect b 2 as well.