Boosting Problems

guitarXgeek · #1 09-23-2004, 07:41 PM

Hey guys, I'm having a bit of trouble boosting as of this afternoon. I was coming home from school and a buddy of mine was behind me, so I decided to give it a little WOT in 2nd gear

. Anyways, I noticed that it didnt feel quite as strong at all as it usually does. I did a 3rd gear pull immediately after to see where my boost was, cause I had just installed a MBC (bleeder-type) the previous evening. To my surprise, the gauge shot up to around 22+ psi!

It was only there for a maybe a quarter of a second, so no damage was done (at least I think). I pulled over to the side of the road and turned the MBC ALL the way out, so that the boost would/should drop to around 9 psi (I think that's what the actuator is set to). Then I went out and tested it again, and results showed it was still boosting insanely high, ~22 psi.

This kind of worries me, because I had been boosting earlier in the day today with no problems and boost stayed at ~15 psi. I'm thinking maybe the wastegate is just stuck closed. I don't know why this would be, but it's the only thing I can think of right now. I tried pulling on the actuator arm to see if it would move, and it didn't (not sure if it's supposed to or not). Is there any way to test if the wastegate is staying closed shut? What if I just disconnected my MBC and tried it out?

Any help would be appreciated!

Matt

kjewer1 · #2 09-23-2004, 07:49 PM

If you are using a bleeder type MBC teed into the WG line, turning it out (opening it up) will raise boost, not lower it. Close it all the way if this is what you are indeed using, and see if it drops. Bypassing it will certainly tell you if its the MBC or something in the WG system that is malfunctioning. When people have boost issues, I always recomend to first run a line stright from the manifold to the WGA. That will show you what the WGA and WG are trying to do, without interference from added boost control devices.

guitarXgeek · #3 09-23-2004, 08:18 PM

Nope. I shut it all the way and it still didn't drop.

kjewer1 · #4 09-23-2004, 08:19 PM

Bypass it and let us know what happens.

guitarXgeek · #5 09-23-2004, 08:43 PM

I ran the line teed into the bov line straight to the actuator. The results are a LITTLE better, but its still at about 19-20 psi, as opposed to 22+ like it was when the boost controller was there.

guitarXgeek · #6 09-23-2004, 09:54 PM

Should I be able to move the WG arm back and forth? Cause mine won't budge at all.

kjewer1 · #7 09-23-2004, 10:25 PM

Thats normal, the spring is pretty strong. You really have to put some nut into it before it moves. On the car, its almost impossible.

Is it spiking to 20 psi then coming back down, or is it acting normal at first then creeping to 20 psi? What turbo is this?

Edit> Just saw some mods in your sig. Dont see a turbo there. If this is the T25 its definitely a spike, nt creep. Its hard to get rid of spike on a turbo that spools as fast as a t25 does.

guitarXgeek · #8 09-23-2004, 10:33 PM

Yes, I forgot to mention that i'm still on the t25. It's definitely not just a spike. It seems to be staying at high boost for good (until it inevitably drops off, of course). I haven't tested this thoroughly though, because I don't want to blow 20+ psi of hot air into my almost stock car for any type of prolonged period of time. It stays up there for a least a second or two, since that's the only amount of time I've exposed it to. I've never seen/heard of a spike that holds for over two or so seconds.

EDIT>>> I don't know if this is relevant or not, but I still have the BCS plugged in. The hoses have all been removed, but it's still plugged into the electircal port thingy. And both the source on the compressor housing and intake pipe have been capped.

kjewer1 · #9 09-23-2004, 11:36 PM

HAve you tried using the stock BCS again? I wonder if that will change anything... At any rate, the spike is at low to mid rpm, where fuel supply is still adequate. At high rpm where fuel supply is an issue, it drops off. So I dont think it will hurt anything. I did it for a long time. Its not very efficient though, as you know.

The best way to get rid of spike is to make the WG open faster. That means a MBC that is fast (bleeder type is the exact opposite of what you want), rigid lines that wont flex (reinforced high pressure fuel injection hose works for me), and a good source. Sharing with the BOV may not be best. Disconnect the WGA arm at the flapper, I Think its the same setup as mitsu turbos, held on with a cotter pin or similar. MAke sure that the flapper arm moves freely! You cant really lubricate it since it gets so hot, so hopefully its good. Thats just about it for factors affecting spike.

Shpyder · #10 09-24-2004, 02:51 AM

maybe the MBC is faulty....i know mine took a lot of tuning to get right...the turning of the knob and the boost i ran was not a linear function...5 clockwise turns got me up from 10-12 psi only, and the one more turn wormholed me straight up to 16. isnt that crazy? so myabe its your mbc...i know that u can spiked as high as 22 if you dont run an MBC, as what was happening to me a while ago...?

guitarXgeek · #11 09-24-2004, 09:59 AM

Well, I'm just going to keep off the throttle (it's tough) until tuesday or wednesday, which is when my joep mbc should arrive. I'll let you know if it helps!

kjewer1 · #12 09-24-2004, 01:56 PM

Please do! I'm quite curious.

guitarXgeek · #13 09-29-2004, 06:31 PM

Well I got the JoeP installed today, and I must say it is a very nice piece! However, it did not help in solving my boosting problem. I'm still hitting 22+ psi. I started in 3rd gear at about 2k even and let it go. I watched my boost gauge closely, and it went straight past 15 psi and kept going, I let off at 20 or so, cause I didn't care to see how high it got. I'm going to try a few things this weekend with the wastegate to make sure it's working properly. I'll keep you updated!

96spyderman · #14 09-29-2004, 09:20 PM

Quote:

Originally Posted by 95 GSXracer

Thats normal, the spring is pretty strong. You really have to put some nut into it before it moves. On the car, its almost impossible.

Mine is somewhat stiff but I can still move it without puttin some nut into it... ?????Good or Bad????

kjewer1 · #15 09-30-2004, 03:43 AM

Are you getting excessive lag? If not its probably fine and you are just too strong for your own good.

If you have a T25 it may be lighter than the mitsu actuators. Cant remember the last time I tugged on one of those...

SOmething is wrong if its shooting straight up to 22+ psi and not falling back. Are you sure its not rising to set boost THEN creeping up to 22 psi? I cant even remember what turbo you have

Oh yeah, T25 it looks like. I would put a line from an air compressor on the actuator and see if you can make it move. Or remove the cotter pin, slip the arm off, and make sure the flapper arm swings freely. If the T25 spring is lighter and 96 spyder can move his, maybe your did get porked somehow. Slide that arm off the flapper and see if both move freely. Let me know.

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