2jz Sequential Problem or not

[1jz68u]

Just wanting to know if this is how the setup is supposed to work or if there is a problem with mine.

If i rev past 4k then back off then on power again i only get 1 turbo working (0.5 bar)

if the revs drop below 4k then i go again all good.

so just when i back off in high revs i get no pressure to the other turbo, i assume this is not the way that the setup is supposed to work but if its not what is the problem??

did the guys that have used a supra or 2JZ on the track have this problem??

thanks

[PlacentaJuan]

yes you get this abit if the accelerator is around the 'changeover' area.

old and leaky vacuum lines (leaks the pressure stores to actuate the second turbo actuators), old or faulty solenods (that stick or dont operate consistently) can cause this problem.

have you turned the boost up past factory levels?

when you say "If i rev past 4k then back off then on power again i only get 1 turbo working (0.5 bar)" do you get full boost (12psi) before you back off?

yes i try not to keep the pedal anywhere near the changeover because sometimes i get the same thing. sometimes i get no boost at all when i re-apply the throttle!

[1jz68u]

yeah full boost before backing off.

i am running 1.25bar.

ok i will give a full example.

change to 2nd coming into a corner, low 5k rpm, pedal, no boost, change to 3rd full boost.


does that make anymore sense?

[PlacentaJuan]

yes that sounds like how the sequential syustem works

btw i assume manual gearbox?

CAMBELT on these forums knows how to reco the solenoids for 2jzgte, and he reckons it fixed the problem you are describing. i will do this next time i pull everything apart.

i guess i have just gotten used to it, but i remember the first few times it happened it was quite scary, and if i was tryont to overtake someone it could have been dangerout too.

the other thing you can do it change the sequential to paralell mode then you dont have to worry.

[Draven]

I think toyota designed the solenoids with a 5 year lifetime to encourage people to go single turbo (which, let's face it, is the man's solution to this problem)

[Norbie]

I had similar issues which I "fixed" by switching to TTC mode, but later "fixed" even better with a big single conversion. Fixing it properly is too much of a pain with all those vacuum lines and impossible-to-get-at solenoids.

[PlacentaJuan]

yes i will be taking my engine out to replace all the vac lines.

my back has spasms just thinking about doing it in-car.

[wilbo666]

I had similar issues which I "fixed" by switching to TTC mode, but later "fixed" even better with a big single conversion. Fixing it properly is too much of a pain with all those vacuum lines and impossible-to-get-at solenoids.

Yeah he sold the turbo setup to me and let me diag the problems

1) VSV for wastegate was stuck open

2) VSV for the IACV was blocked so the IACV would stay open once you opened it

If you have a search I did a list up for testing all the VSVs once

Cheers
Wilbo

[1jz68u]

Yeah he sold the turbo setup to me and let me diag the problems

1) VSV for wastegate was stuck open

2) VSV for the IACV was blocked so the IACV would stay open once you opened it

If you have a search I did a list up for testing all the VSVs once

Cheers
Wilbo

is this what you were talking about?

http://www.toymods.net/forums/showth...t=36633&page=2

[wilbo666]

Yeah that is the one, my last post

http://www.toymods.net/forums/showpo...8&postcount=32

Cheers
Wilbo

[1jz68u]

i am possibly very silly but i have no idea how to test all the things listed.

but on a side note i have now changed to TTC and sometimes i almost have the same problem, but slightly different.

so now sometimes accelerating in 1st won't make full boost, sometimes in 2nd will run .5 bar then at about 5k will jump up to .9 (low boost setting)

does this narrow it down at all??

also there is a rattle at idle and low revs that sounds like it is coming from the turbo area.

[PlacentaJuan]

let me guess you did the electronic ttc mod? (ie swithces into the ecu directly)?

i have never done it (because i dont trust it) but i use 2 one way valves in the actuator lines, which keep them held open.

that was you are in ttc mode no matter what the ecu is doing.

also you dont get the dodgy rattle either.

[1jz68u]

nah i did the 5 min one where you bypass both VSV's and just connect the hose from the top to the exhaust thingo down the bottom.

will give your way a go.

[1jz68u]

ok have changed back to seq and now i cant get stable boost at all... nothing. under 3k rpm will go to .7 sometimes then drop off and come back up to .5 at 5k????

wtf is going on? are my turbos fucked or is it something to do with the seq system?

wilbo if you could give me an idea of how to test all that stuff it would be great.

[wilbo666]

wilbo if you could give me an idea of how to test all that stuff it would be great.

The resistance tests are done with a multimeter (You can but one for like $10 these days from the likes of Jaycar )

The 'pressure' / 'actuator' tests are done with some vac hose and a large plastic syringe. You should be able to get a suitable syringe from a pharmacy.

To actuate the valves (Turn them on/off, or open / closed) I got an electrical plug that fitted the VSVs (You can use 1 plug if you remove the 'keying' section of the plastic) and then extended the wires from the plug so that I could connect them to the battery when I wanted to turn the VSV 'ON'. Polarity doesn't matter

Make sense?!

Cheers
Wilbo