2JZ-GTE Boosting Issues

[wilbo666]

OK.

EDIT: I suspect something in my system isn't right See my next post for a better description...

/end edit

I need an exhaust restrictor in my 2JZ-GTE, it has 3" zaust (with cat), and front mount IC.

Boost is not even close to controlled (Shoots off my 20psi gauge ). On a side not it seems that my sequential mode is broken, I only get ~5psi all the way when in sequential mode... note to self: check front turbo wastegate is working...


A few people have done different things it seems..

Norbie had a 3" -> 2.5" cone in his...

BWMTurbo says 3" -> 2.25" cone...

Project sleeper had a flange with a 2.5" hole in it...

And some other sources say a plate with a 2" hole...

While I'd like to try them all, as the same time I'd rather not!

Cheers
Wilbo

[Draven]

get a real turbo + external wastegate?

consensus (well, majority really) seems to be that as long as it has a 2.5" hole in it somewhere, you'll have decent, controllable boost. afaik, the 2" hole is unnecessarily small.

[BMWTurbo]

How much boost do you want to run Wilbo? I can hold 15psi ish steady with the roughly 2.25 cone.

I had it at 2.5inch but had to reduce to add weld around the inside of the cone throat to reduce it's diameter back in order to not boost spike. I should also note I made a new transition from the factory cast 'butterfly' section to a single 3inch pipe. This smooth transition might be the reason I needed more restriction then other's have that have made thiers.

My exhaust is a single 3inch, through a 3inch hi-flo CAT, 24inch long 3inch resonator, back out a single 3in dual 3out free flowing muffler.

[wilbo666]

Well it seems that something isn't quite right with my turbo system...

In stock seq mode it will only make ~5psi all the way to redline...

With my ETTC switch (diodes from the IACV VSV and EGV VSV at the ECU to a switch that GNDs) on I get massive overboost (20psi + off my boost gauge).


So far I have checked the IACV and EGV and thier VSVs. I used a syringe to apply pressure and watch them actuate.

I haven't checked the front turbo wastegate as yet, will do as soon as I can.

In the mean time does anyone have any suggestions?!

I'll be going over all the hoses etc later today...!

Btw I now have a 3" -> 2.3" restrictor in place...

Cheers
Wilbo

[wilbo666]

Well checked the VSV on the front turbo wastegate...and it was stuck open

My spare front turbo VSV had a broken nipple...so I had to take them both apart and make one good one from the two. In case anyone cared the 'broken' one had a little pieces of what looked like rubber about 0.5mm long floating around inside it that was causing it not to shut...

So Seq mode now works (I would have thought it would have worked before, so I'm a little confused there..)

And ETTC mode also works as expected...

Even with the restrictor boost seems to be going pretty high...for testing I still have boost cut on atm, but will get rid of it soon and do some logging...see what it shows...

Oh and a pic of norbs old dump...


And the zaust


Cheers
Wilbo

[BMWTurbo]

Looks good Wilbo... 2.25 it is hey

[wilbo666]

Well it is 2.3" already!

Just about to turn boost cut off, go find a highway and see what it suggests peak boost is...



Cheers
Wilbo

[adamaw11]

Impressive problem solving!

sounds like you're ready to run a mid 12 at the drags tonight

[Draven]

could you have managed a straighter exhaust?

[wilbo666]

This still isn't sorted...

and after the drags the plot thickens...
http://www.toymods.net/forums/showpo...&postcount=285



It seems that even in ETTC mode there is quite a dip in boost and then it comes back on, it goes 5...dip, 18, check engine (no ecu code logged, and must boost cut defender is set so that the ECU sees a max of ~12.1psi [4200mV]...)

I will have to keep investigating...


Edit: Draven, I do what I can

Cheers
Wilbo

[wilbo666]

Datalog from the first drag race...

Can see the boost dropping when the engine is cutting out

Also
http://www.toymods.net/forums/showpo...&postcount=290

Cheers
Wilbo

[BMWTurbo]

That in sequential mode??? you will get a 'dip' in sequential mode when the second turbo comes on line.

How is the 'boost limited' to the ECU? Sounds like a EBC issue to me. Where is the EBC connected?

Attachment 6800

[wilbo666]

Yes sequential mode,

NO boost controller fitted.

THe boost is limited to the ECU via the same circuit that does the logging. My micro takes an ADC sample, checks to see if it is over 4300mV (or whatever I set) and then if it is over 4300mV it caps its output to the ECU to 4300mV. I'm using an R2R network for my DAC, so it is nice and simple.

I've tested that the output is getting capped.

I also tried 4200mV

I think you are right tho, it does feel like the issue is in that ball park!

estabane has a 'proper' boost cut defender that he can lend me to try that.

I'm still not convinced that the rest of the turbo system is working correctly to be honest, so I need to go over the parts of that I havent checked yet (pressure storage, exhaust gas bypass...)

Cheers
Wilbo

[brett_celicacoupe]

what sort of timeframe is there between the 'cuts'??

the fake rev limit has a hysteris (spel?) more then the rel rev limit but less then the boost cut (right way around?)

the fake rev limit cuts for about 0.3s?

[wilbo666]

what sort of timeframe is there between the 'cuts'??

the fake rev limit has a hysteris (spel?) more then the rel rev limit but less then the boost cut (right way around?)

the fake rev limit cuts for about 0.3s?

The thing is it isn't at the limiter....

Cheers
Wilbo