peachykeenwight

So... I've been convinced that the boost solenoid on my old school Profec B is done for.

However, recently, I invested in a manual boost controller out of curiosity. After hooking up the little thing and giving a couple of turns, to my surprise, I was still pegged at 11 psi during WOT pulls. (11 psi = my wastegate spring). Huh? I warily turned the controller a tidbit more just to make sure I wasn't missing something- still only 11 psi.

This is mildly frustrating seeing as I am going to be tuning for alcohol injection soon and I'll naturally want to turn the boost up.

I'm stumped! Any one have ideas? I'm hooking everything up correctly (and just to make sure I even switched the vacuum lines around just for *****)... possibly a wastegate issue?

RETed

Turbo is bad.
Too much fuel.
Extremely lean.
Exhaust too restrictive.
Intake too restrictive.


-Ted

G's 3rd Gen

iTrader: (11)

Has anybody found info. as to test the solenoid? It would obviously be easy to switch out and try. Although they dont make the B anymore. G

peachykeenwight

Just pulled the engine about two months ago, turbo was in perfect condition. I always let the coolant/oil warm up before boosting and give it a bit of downtime after hard pulls. I'm 99% sure this is some sort of weird vacuum issue that is over my head.


Just had her tuned, eliminating the possibility of these. I pay attention to my wideband periodically as well.

I wouldn't think these would be factors. I have a 3 inch downpipe which leads in to a 3 inch blank cat (Bonez) and then an A'pexi GT catback. The only part of the system that is restrictive is the piece inbetween the cat and the catback which is about 1/8th of an inch smaller piping than the cat's outlet. I wouldn't think this would cause a problem though?

The intake is a 4" 45 degree bent SS pipe with a 4"IDx6"ODx9" long K&N. It's supplied with a healthy dose of air as well.

peachykeenwight

Yeah, I'd have to dig around to find a used Profec B solenoid, or possibly just buy a "universal" one.

The only thing that gets me is why doesn't the MBC work then? I mean, it's like the most simple boost controller in the world... maybe I'm not turning it up enough for it to start adding boost?

I'll mess around with my vacuum lines some more.. see if I can't figure anything out.

I appreciate the feedback, guys.

-Mark

Wankel7

How sure are you that your wastegate is working right? Maybe it is stuck open for some weird reason.

You could always disconnect the boost line to it and very carfully go driving and very carefully get into it and see what kind of boost it builds. If it still can't build past 12 psi with no boost reference going to it...the wastegate might have issues.

James

fastrotaries

I'm with you on this Garret. I'm having similar issues, I suspect it might be the vacuum lines, so I'm stepping up to a SS hose of some sort. But I would love to test the solenoid out, just to rule it out. $300 + for a new EBC is too much for me, when I don't even know what's wrong with the old one, or why it died.

NOPR

not to insult you, but are you sure the MBC is correctly installed? over half of the ones i see are installed incorrectly, and ive heard many people tell others incorrect ways to install them. the MBC should be tee'd off of the wastegate line with only one hose going into it, when fully closed it should not in anyway affect the air going to the wastegate solenoid, when opened it should bleed off air into the atmosphere, like a controlled leak basically. this requires the turbo to make more psi before the wastegate will see the psi it opens at. If you already know all this and its installed correctly, sorry.

RETed

Actually, this is not correct for an EXTERNAL wastegate...


-Ted

NOPR

how so? i always thought it was the same internal/external?