legacycentral bbs

After installing it, it did nothing. Before I could turn my MBC all the way up or down, now it is stock all the time. I followed the instructions to the T. All connections were good too.

I'm a little confused.

Before you installed the fuel cut defender, the MBC was working correctly?

And afterwards, the MBC only allows you to decrease boost below stock levels? Or boost levels are stock all the time?

And where are you measuring boost?

Yes. I'm measuring it out of that line off the intake runner.

Do you trust your gauge?

And what's this about having the stock boost controller in the loop?

vrg3 wrote:And afterwards, the MBC only allows you to decrease boost below stock levels? Or boost levels are stock all the time?

Which is it?

It would really help if you could give a very clear straightforward chronology of what you did and when what happened.

I run a Joe-p and it's crap! It's way too sensitive to changes in atmospheric conditions and boost spike can be severe.

I have a friend that went from a Joe-p MBC to a TXS Pro MBC on his rex and he said it made a huge difference in boost stability and consistancy.

When it comes to getting a cheap, piece of crap MBC like a Joe-p or making it yourself then it's a toss up IMHO. I definitely wouldn't pay for a new Joe-p unless you're in the sticks and have no options (I got mine for a beer ) but I think you get what you pay for sometimes. So, Joe-p or hardware special? Either way, they're good to get the boost turned up but first chance I get I want to ditch mine for something better.

Vrg3 - Both. I can turn it down and when I turn it all the way up, it's stock levels.

1) Took out the ecu connecter and spliced in your FCD.

2) Hooked it all back up.

3) Took of my air box. Re-oiled my K&N.

4) Took the connections off the factory MBC and put them on the MBC I have.

5) Put things over my factory MBC to plug up the connections.

6) Put everything back togeather.

You said before you had both the MBC and the factory boost control plumbed in series at one point...

And what was happening with your boost at each point in that chronology (including before #1)?

Do you trust your gauge?

I do trust it. It has always worked before.

Before #1 I could boost it tell FCD happened with the MBC connect inline with the stock BC. After the FCD and the factory BC not inline is when I couldn't boost it above 9psi.

So with the stock configuration your boost gauge showed something like 9 psi of boost?

What boost level do you reach if you just connect the wastegate actuator directly to the compressor outlet?

Does your MBC have some kind of small bleed orifice on the outlet side?

I haven't done that connection of the wastegate to the compresser outlet.

I see no bleed valve on the side.

Hmm. Ball-and-spring boost controllers do need a very small bleed orifice (it doesn't have to be a valve) on the outlet side in order to vent pressure between the controller and the wastegate actuator when the throttle is closed. I wonder if maybe after all your problem is a poorly designed boost controller.

If there really isn't a bleed, try drilling a very small (maybe 1mm) hole in the outlet side.

What does the bleed do?

ok when i put a turbo smart fcd in my car it changed my boost, every turn on the little dial would make me have to set the boost controller agian, it plays a funny trick on the boost setting. there is also to types of boost cuts on our cars. the little black box on the passenger corner of the strut body, and one in the ecu, to get rid of the first CUT, crimp the vacum line shut, un plug it from the brown sensor, keep the vacum still in the line that will stop the first boost cut, it wont mess up your boost settings. you can hit 18psi to 20psi with no problem, over that much boost, you run in to the ecu cut.

$J-MoNeY-$ - It prevents pressurized air from being trapped between the boost controller outlet and the wastegate actuator. Imagine you're driving hard; you're at full boost. There is air pressure pressing on the wastegate actuator to keep it open enough to maintain that boost level. Then you slam the throttle shut to shift. The ball-and-spring valve in the boost controller closes since there's no pressure pushing on it. At that point the outlet of the boost controller, the hose to the wastegate actuator, and the pressure side of the wastegate actuator all form a closed system with a pressure above atmospheric. This could hold the wastegate open.

Nico - It sounds like the Turbo Smart FCD was screwing with the pressure sensor signal even off boost (including barometric pressure readings), and like you had your boost controller connected in series with the stock boost control. Is that true?

I think you're a little confused about the fuel cut. Both fuel cuts you saw were caused by the ECU.

The "black box" you refer to is the pressure sensor. The "brown sensor" is the pressure exchange solenoid. They work together to allow the ECU to measure manifold pressure and atmospheric pressure. And when manifold pressure gets too high, the ECU cuts fuel to protect the engine.

I can only guess that the second fuel cut you ran into was a result of your exceeding the MAF sensor's measuring range.

Ha! I feel like a moron. I had a massive boost leak in one of my IC rubber connectors. They are crap. Anywho, fixed it and she's boostin fine now.

Alright, killer! Why is the stupid stuff always so hard to figure out? It happens to all of us so no worries.

Hehe, cool. I'm glad it was a simple problem.

So your turbo was actually making much higher boost than your manifold reached, and you were running overly rich at that high boost. It all makes perfect sense.

Exactly, and your FCD is working fine.

Nice.