RB20 issues - please help

[ivysbuddy]

I know i don't have many posts. I've been lurking around off and on but i'm not much for large forums--it's no offense to you guys. So please, try to avoid flaming me over my post count. I'm just looking for help, and if the community here ends up being cool about it, i'll keep coming back. Thank you.

So here's my problem. I'm not running right now, and I'm completely freaking stumped.

Back story: I bought the car with a dirty MAF and both the stock BPV and an aftermarket HKS BOV. I cleaned out the MAF with some carb cleaner almost right away and saw an immediate increase in both power and mileage.

I had a local auto shop that i trust very much cut off the BPV and weld the hole closed. I stopped up the BPV dump tube with an adjustable rubber stopper and capped off the vacuum line that runs to the BPV from the intake manifold.

After this, it drove like a BEAST. I only have the stock boost gauge and no AFR gauge, but the stock boost gauge's needle was alive for the first time since i bought the car, and for the first time i actually heard the wastegate being used. I would hit about 12psi (around 6 100xmmHg on the stock gauge) and the wastegate would kick open, whooshing like a Paris Hilton queaf.

However, it wasn't all fun and games. sometimes the stock boost gauge would die completely; the needle would just drop to below -7 vacuum and just stay there, but that's something i can live with. Sometimes while coming to a stop the car would drop below idle and just shut off. Everyone once in a while it would catch itself and adjust--but more often than not, i would have to catch it. Because of that, I drove her pretty carefully for a few weeks, hoping that the ECU would figure it out and start to behave normally. It seemed like it was working, because the idle-offs weren't happening nearly as much.

I understand that this is fairly normal for a recirculated car with a MAF and no aftermarket fuel regulation when a BOV is used in place of the stock BPV. I have the HKS recirc fitting on its way to my house right now which should fix that problem. That is not the primary issue.

This is: I took the improvements as good signs and took her to my favorite run spot. I dropped the hammer for real, and she ran like I felt she should--freaking FAST. But after the run--which is only a mile or so from my house--she started acting up. The wastegate opened at about 5psi, but the turbo was still spooling. Otherwise, no funny noises.

I got her home and looked under the hood. Didn't see anything obvious, no hoses were blown off or anything. So i told myself it was just my imagination. No big deal; if it were anything serious I'd deal with it after work the next day. I woke up the next morning, cranked her up, and...she shut off.

That is where she was when i considered her crippled and in need of help. Every time i cranked her, she would rev to about 5k then just shut off. I could keep her cranked with some throttle waggling, but as soon as i took my foot off she died. A friend said at one point that his car does something similar and he just "warms her up" before letting off the throttle, it sounded sketch to me at the time and still kind of does, but i tried it anyway, to no avail...kept the needle pinned at about 5k for 30-45 seconds, and then she just died again.

I figured i must have blown a vacuum hose or something off; unfortunately, i've taken the entire exhaust side of the engine bay apart and haven't found jack. Everything looks like it is where it's supposed to be. I don't think the wastegate actuator is stuck open; comparing the position of my controlling arm, it looks about the same as some rb20 pics i've seen.

I've heard it could be the TPS (throttle position sensor) or the knock sensor gone bad. Looking this stuff up, it looks like those could be potential causes and relatively easy fixes, but I'd like to see what you guys think before i start looking for USDM replacements or spend Jesus-knows how much ordering JDM parts.

Thanks for your help, guys.
Modified by ivysbuddy at 9:34 AM 11/30/2009

[Gavin Johnson]

your using the gtst gauge cluster? it uses a sensor that looks like a map sensor on the firewall, id check connections/ vaccum lines there to see if they are loose or broken, and check all connections for boost leaks.

[Yellow4g63]

Your RB20 had a EGR valve on it? pics please.

[ivysbuddy]

Your RB20 had a EGR valve on it? pics please.

EGR = BPV. Sorry about that. I was thinking the right part but typed the wrong acronym. Posted too early without enough coffee. Fixed.

[Carl H]

pull codes from the ecu, if its all clear then move on.