mkriebs

Ok, my buddy bought a TC with the TRD super on it... well, we noticed the other day that it was just not building boost as we would expect it to. It has a 9lb pulley on it, TRD flash, and header, intake, exhaust, S pipe.

Basically the boost builds really slow, then right at redline spikes like crazy to the preferred 9 psi. Now, I know cars, and i know how superchargers build boost kinda linearly. This will build bout 3-5 psi, then level off til it spikes to 9psi around 6k rpm.

Now, I have several theories of what this could boil down to, but wanted other's opinions too (since i am more of a turbo guy...). I checked the hose clamps to see if they were loose, and a couple weren't TIGHT, but were snug. Also, are these supposed to have T bolt clamps, or regular worm style clamps? We just ordered T bolts regardless, but JW.

Also, on the stock bypass valve... is there anyway to increase spring pressure, or should he go to an aftermarket one? I know Forge makes a good one we could go to. I think that it may just be pushing too much boost for the BPV to hold back.

Those are my 2 biggest theories... any more ideas??? I appreciate all responses in advance!

imsonofagun

The stock BPV has been known to be bad. The diaphragm can tear over time. It's also not adjustable. Even an upgrade to the Bosch 110 Sport BPV is a big improvement.

For a quick test you can try installing the stock BPV "backwards" or "reverse". If there's an improvement in performance, replace the BPV. I wouldn't drive with the BPV installed wrong for long though.

The theory:

Normally the air enters from the bottom and exits through the side.



Try rotating the BPV so pressure enters the side and exits the bottom.

liltofuboix

iTrader: (1)

if your looking for more midrange switch to the mmw header. maybe that will help instead of the higher rpm header you might have.

mkriebs

Yeah, I have been tossing around a Forge 007... looks to be a good option. IDK how far we can up the boost with that though... I think he may want a 12 psi pulley... so it will have to hold that much. I think the 007 is adjustable (I have looked at so many I am getting confused).

imsonofagun

The Forge unit is adjustable and can be rebuilt. There are different springs and spacers that can be used to work at any pressure the TRD s/c can put out. The biggest thing is making sure that proper maintenance is done every six months.

mkriebs

Proper maintenance on the SC or the BPV??

imsonofagun

proper maintenance on the BPV.

mkriebs

What would that consist of, if you don't mind sharing?

imsonofagun

http://www.forgemotorsport.com/media...service(1).pdf

gompka

iTrader: (5)

If its not the bov, then check to see if the belt is slipping, if its not slipping, it maybe time for new bearings and/or shaft, thats a worst case scenario. If you do 12psi i would highly recommend installing a grease fitting and getting a vented hood.

GammaTNT

iTrader: (8)

i didn't know bpv needs to be check. i am going to check mine this week.

mkriebs

Good info, thanks! It seems to me that 10.5 psi is going to be more the route my buddy will be able to afford to take, unfortunately. But I still think we could get some good power outta her.

mkriebs

AND THE PLOT THICKENS!!!!

Ok, so my buddy's battery died today while he was at work. No big deal, right?

WELLLLLLL... when he starts the car, he notices it is idling with a vacuum of 12-15mmhg, and as he starts driving, he notices it feels alot stronger. So, he pays attention to the boost gauge, and notices at cruising speeds, he is boosting 1-2psi (as opposed to the 10mmhg vacuum before the batt died). And he noticed his boost built alot faster, and ACTUALLY hit 9.5 psi, like it had never done before.

So, my thoughts might be that there is a code pending, and that the ECU is limiting it, or that there is a bad solenoid that controls the BPV. I told him to unhook the battery for the night, and see if it does it again.

Any more thoughts? We really appreciate the help guys! Keep the ideas comin!

mkriebs

H'okay! The ECU reset apparently didn't work. IDK if he did it right or not.

I am so stumped. I am thinking maybe its not getting enough fuel so the engine is cutting the boost. I am about at my wits end, and I am not going to let this car win.

gompka

iTrader: (5)

Ecu/engine cant cut boost unless there is a leak and its leaking out. Also not having enough fuel won't make you boost less. The supercharger is belt driven and engine rpm is the only thing controlling the boost.

mkriebs

BPV controls the boost. ECU controls the the solenoid that controls the vacuum to the BPV.

gompka

iTrader: (5)

NO! You need to do some reading man. BPV only blows off boost when you close the throttle, thats what all bpv's and bovs do they DON"T control boost. The ECU in no way shape or form controls the bov. I'm trying to help you out here...

Thorium06

iTrader: (5)

negative ghostrider, listen to gompka

mkriebs

Wow take a chill pill man. I know my cars, I am pretty sure. I am just stumped by this supercharger. If the ECU has no control over the BPV, why is there a vacuum line to it?

Thorium06

iTrader: (5)

the vac line allows the valve to open, but it doesnt run to the ecu at all. the valve wasnt intended to "bleed" boost, its just ment to open and relive pressure when the throttle closes so it doesnt try and spin the supercharger backwards