2JZ turbos overboost issue

[Ribfeast]

Hi guys,

I have a twin 2JZ setup on my 1JZ, with custom manifold etc, and external gate.

I seem to have an overboost issue, even when the boost controller appears to be connected correctly. As I have never used an external gate before, can someone tell me if I have this hooked up correctly?

At the moment it seems to run 9-10psi for a few seconds, then rockets up to 2.45bar (35psi!!) in a split second. At least my intercooler pipes aren't popping off

Boost controller is a Blitz DSBC Spec S. Front turbo is steel wheeled, rear is ceramic (rear steelie died).

This is how the boost controller manual says to setup the gate:


And this is how it is setup. I previously had it hooked up to the manifold rather than before the throttle body, but this made no difference.



I have no idea what brand wastegate it is, as the kit was bought secondhand.
The boost nipple on the rear turbo compressor housing is welded shut, so boost is referenced from the front turbo housing.

"Vacuum" is printed on the top of the wastegate, and there is a grub screw in it also. Not sure if this is relevant.

Any help appreciated

[richzx]

Have you checked the spring in the wastegate and its still there and working? WG not jammed open??

[misk]

hows the 2jz turbos go on the ol 1jz?
props for getting them fitted!

[Ribfeast]

Cheers I'll pull the housing off and see what the internals look like. Perhaps the gate got clogged up with gunk from the rear turbo or something.
Can you see anything wrong with how I have the vacuum lines set up?

The turbos are slightly more laggy, but come on hard and sound great

[woggin]

The turbos are slightly more laggy, but come on hard and sound great

yea i bet, 35PSI hard!

[woggin]

does it actually 'feel' like 35pounds?? or does it just say that, coz im sure 35psi would cause some awesome lean condition!!

maybe hook up a mechanical boost gauge and just check it actually is that much pressure!! that would be a good first step!!

solenoid in wrong way possibly, dam man it is bloody hard to read some of that text in the pics!

wog

[rob_o]

My single turbo wastegate is set up a little different.

I have a line going from the throttle body, through the boost controller, into the wastegate. The second line from my wastegate is not connected to anything (just venting).

What are you connecting to the turbo? I thought that was only for internal gated turbos?

[wilbo666]

A few things,

Firstly, does it run 'wastegate' spring pressure with the boost controller disconnected...if it doesn't you need to sort out why before continuing.

Secondly...do you have the solenoid connected correctly? (Looks like a Spec S solenoid?)

Thirdly... do you have the DSBC setup correctly for use with external wastegate? (the switch on the rear of the unit is set to WG)

http://www.blitz-performance.com/inc...Spec%20S&R.pdf

Cheers
Wilbo

[Ribfeast]

Cheers for the help guys, car is now sold so I didn't get a chance to implement the suggestions above in the end Buyer says the wastegate moves freely and seems OK, so must be how the hoses are hooked up perhaps.
I have passed this thread on to him, hopefully he will post once his Toymods account is approved.

[Dieseltrain]

Damn, What ya gettin Now Ribfeast ?

[Ribfeast]

Got an old 1992 Holden Nova/Corolla 4A-FE as a daily, going on a holiday to Canada and Alaski in June/July 2008. Will look at purchasing something NA but sporty and good on fuel, such as an S2000 if money permits. Failing that, something like an MX5 or Integra etc. Prefer RWD.

[CrUZida]

While your back there in June 2008 can you sell all my shares for me?