hp18racer

Best way to test the waste gate without driving the car is to use an air compressor with a pressure regulator and a gauge that you can use to test the parts. Start out by testing the boost control **** in isolation. Connect the output of the boost controller to a gauge and nothing else. Does the output pressure regulate properly? Then connect the output of the **** to the waste gate with a gauge teed into the line, does it still regulate correctly? If both of these test right, next is probably to disconnect something in the exhaust so you can see what the valve in the waste gate does when you apply pressure.

I have had a boost **** fail due to oil in it. I have had a waste gate fail due to an internal leak. I have had it fail to work right because I had a line pinch or a line leak.

I understand your frustration, hope this helps.

eric951turbo

thanks for the advice. But I'm not really equip for that.

QUESTION: I've read again the LR site about the dual port and they say that boost can be set as low as 9psi. This is what I'm getting all the time, even if I try to adjust my MBC.

Because of that, I have a feeling it could be my MBC. Stores are close tomorrow, But I have a Lindsey Boost enhancer laying around the house somewhere. Do you think I could use that to control my boost.
I would like to give it a try to see if its really my MBC that is causing all the problems. I'm freaking out a little, I really dont want to miss track night next monday : )

onspeed

Problem with the boost enhancer as a boost controller is that it'll leave the wastegate open a little longer than it should, so you'll see more lag like between shifts.

The spring pressure of the LR unit is 9psi, hence that's the lowest boost you can run. Make sure there's no holes in the vacuum lines. I know when some of the nipple fittings for my car are a bit large and eventually cause my silicon line to tear. Running in single port as I said earlier should have restricted boost to 9psi if your MBC was indeed fully open. The fact that it spiked to 25+ means that there was no boost pressure going to the wastegate to open it, and if you're sure the MBC was open, then that means it must be a hole in the vacuum line somewhere or the nipple fitting came loose on the WG or something.

hp18racer

Your current plumbing resulting in 9psi boost says that you do get boost pressure to open the gate and no pressure on the other side of the gate.

When it is spiking to 25, you are getting no differential pressure on the gate. This is either from incorrect plumbing, bad MBC or a leak in the diaphram of the wastegate. With a diaphram leak the gate will work in 'single port' mode but not dual port mode. The leak causes pressure to build on the regulated side, no more differential pressure, boost spikes.

How about a cheaper way to test components. Buy a pressure gauge and some silicone hose. Hook up the outlet of your MBC just to the pressure gauge, leave the corresponding port on the wastegate open, you should be able to adjust the ready b/t 0 and 9 psi while on boost. If you can get this to read 3 or 4 psi, then hook it back up to the gate and try again. With the MBC set correctly, if you still get boost spikes probably a leak inside the wastegate.

eric951turbo

Thanks for all your help guys. The problem is solved.
One hour and a half testing on a open road this morning.
The problem is my Boost Controller. Now I'm at 10psi.
If I turn it just by one millimetre to release the spring, it jumps to 16-17psi.
I I turn it by one millimetre to put more pressure on the spring, then it goes down to 10psi. The spring in my MBC is finished, kaput. I can't adjust it.
I need to change it.

I'm glad it's only that, I didn't feel like going under the car again (with no lift).
The bracket bolts holding the wastegate are a pain in the *** to reach.

vanosman

k26-8 hybrid
running single port with LBE and other check valves under hood, my Tial WG has 2 springs, removed the smaller internal spring and it functions @12-14psi instead of 22psi overboosting. It's mechanical thing, Tial rated at 15psi but it's too much spring and triggers OB and limp mode !

You don't overboost until 3rd gear right ?

I bought a MBC **** off evilbay, i see if dual port is more steady vs the check valve which isn't real smooth.

I got a cheap fix until i got the Tial opened up , used a ricer blow off with the ****, think it is OBX with anodized blue top **** and horn or horn plate block off. It vented under hood like a ricer has WG on the turbocharger. It's rated 15psi but a few turns would bleed off the overboost & dump it out of the horn which was loud. It was weird sound because you normally hear the whoosh dump with a MAF cone setup between shifts when the backpressure flows back at the turbo. Heard that whoosh under full throttle, it was weird, the weakass spring was lazy when it was opening it dumped too much boost and wouldn't hold for long when you dial it open, it just dumps while RPM's still building, it's like a bigger version of LBE but it's on the intake side up front like the stock.

It would be similar to dialing down the Lindsey valve.

i let you know if dual port with under dash MBC is smoother than the check valves under the hood