Mindspin311

Realized something quite interesting last night.

For the longest time I didnt realize that the previous owner of my car had installed the boost controller wrong, but the car always held 7.5psi like it was supposed to.

Well, after I removed the boost controller I decided to run just the wastegate to see what would happen. After a few minutes of driving it seemed like it would keep hitting about 5.5psi which I figured would be right because if the porting. But then I decided to do a 4th gear pull from 70mph, all of a sudden I look at my boost gauge and the needle is about to pass 10psi. I immediately let off before something bad happened. I did this two more times and each time it climed to 10psi and probably would have hit more. This all happened above 4k rpm.

Shouldnt I have hit fuel cut way before that?

The previous owner said he had an HKS FCD installed when he had the BNR Stage 2 put on but I have yet to see anything by the ECU that looks like the HKS unit.

eriksseven

iTrader: (6)

Well... Is that where the HKS FCD is supposed to be? I really have no idea, but it's gotta be there somewhere if you didn't hit fuel-cut, which is at what, 8.6psi? This would be obvious, but it's not tapped in right by the pressure sensor in the E-bay is it? This is where the RB unit is installed.

Just curious, have you had an opportunity to tune your car yet with a wideband? Or are you just kinda crossing your fingers and guessing?

Also, what do you mean by the previous owner had the boost controller installed wrong? Like, how was it set up? I'm guessing it was a MBC?

Mindspin311

Well I looked in both places, by the sensor and by the ECU, nothing. So Im pretty sure the previous owner just got shafted by whatever shop he brought it to. I have not done any work with a wideband, although I do have one coming in the next few weeks. With the larger secondary injectors, I figured that I would be safe with the extra fuel at the stock 7.5psi.

The MBC was a normal 2 line unit that would be placed inbetween the pressure source of the turbo and the wastegate port. But, for some stupid reason only the input for the MBC was teed into the line running from the pressure source to the wastegate. It was esentially just bleeding off pressure when it was trying to do its job, thats why I took it off. Dont ask me why or how it happened because I just dont know.

I figured that with it off and the WG ported that it will run about 5-6psi but I was suprised when it hit 10psi. From a roll at 3k in 3rd or 4th it would climb to 5-5.5psi between 3k and 4k, but then it would continue on to 10psi or so but I wouldnt let it stay there for more than 2-3 sec since I wasnt sure if I had the fuel to handle.

It then occured to me that I should have hit fuel cut, but that never happened. So either this FCD is really well hidden or my boost sensor is going bad. Although I dont have any CEL codes for the sensor, which is odd.

SureShot

When I install a FCD, I put a bypass switch in the circuit for testing.
I discovered the S5 ECU would allow overboost for 3-4 seconds before giving a fuel cut.

Wankel7

Exact problem I have with my BNR 3 turbo on a S4 hotside. He ported the hell out of it. But when running just the wastegate in 3rd gear or 4th gear it will creep past 10 psi.

Nothing pisses me off more than a lack of boost control.

If you didn't see the HKS FCD around the ECU and it's wire it isn't there. Now, it could be in the engine bay hiding. Trace the wires from the boost sesnor in the engine bay back to the harness. There might be a box there.

James

Mindspin311

Seriously, I thought the whole point of porting the WG was to eliminate creeping. How does that still happen?

Wankel7

Because that WG hole isn't sufficant enough to bypass enough exhaust to prevent creep.

Port it more

Mindspin311

Haha

I figured BNR knew what they were doing and ported it enough already.

Boostmaniac

Yeah, the S4 hotside just won't cut it. If you get a chance, just pick up an S5 manifold and an S5 hotside.

That should solve your problem right there. Just remember to port the S5 a little bit just in case.

Mindspin311

Uhh, I drive an S5, still creeps.

Wankel7

Bryan at BNR likes the S4 because he can port it larger than the S5.

Go figure!

James

rx7 SE

iTrader: (5)

Does anybody have any pictures or links on porting the wastegate?

Wankel7

BNR 3 on a S4 hotside:

MaczPayne

iTrader: (5)

custom weld job on that flapper. It's not something I could do on any weekend, haha.