2jz-gte pinging - was gt35/40 with standard ECU

[Draven]

Joshtix suggested this option to me since my second turbo isn't switching over. Instead of actually looking for the problem, I could just put the gt35/40 on.

No, the possible plan was to put it on with a ~10psi wastegate spring and max the boost at about this, and run standard ecu and injectors.

Does anyone have enough knowledge about the 2jz-gte (vvti) ecu to tell me if this is a viable option? I hadn't even considered it, I just assumed that the ecu would shit itself come time for the second turbo to come on, what with it not having the plugs in to all that sequential gear.

[Norbie]

I seriously doubt the ECU will know or care if you disconnect the boost control solenoids.

A big single will run OK with stock management as long as you keep the boost nice and low. It will make less power than it should but it's not unsafe at 10psi or so.

Might I suggest you try TTC mode before you go to this much effort? This is the quickest way to determine if the problem is a shagged turbo or just the sequential system playing silly buggers.

[Draven]

my biggest concern right now is the engine is pinging... so it's entirely possible the ecu is detecting big knocks as the second turbo comes on and just cutting my boost.. os I want to find the source of that problem first.

edit: which is challenging, since the temps are fine, AFRs are fine, ecu is standard, timing is fine

[Norbie]

My 2JZ used to do exactly that when it had overheating problems. Second turbo cuts in, boost goes up, detonation starts, ECU steps in and basically shuts down the turbos (not sure how it does this exactly but the boost gauge instantly dropped to zero with my foot flat to the floor). At first I thought it was a blown second turbo until I realised it would boost up fine when the engine was cold.

Do you have a boost controller? If so, try turning it down to the lowest possible boost setting and see what happens.

[Draven]

no boost controller, it does it even on a cool engine, temp guage is reading normal, and it's shutting off *just* as the second turbo should kick in - I don't even get the beginnings of that boost.
and it doesn't feel like a blown second turbo - it feels as though the ecu is cutting my power, because the power drops right off, then slowly comes back (but still no boost unless I change to below 4000rpm and wait 2-3 secs before flooring it)

[Norbie]

OK, in that case it's either a blown turbo or (more likely) the sequential system has got its undies in a twist.

Seriously, go and do the TTC mod right now. It takes all of 2 minutes provided your engine isn't hot.

[MR 1JZ]

norbie that TTC mod you speak of...is that the one that causes both turbos to run simultaneously?

[Draven]

norbie: I don't want to do that, since the engine is pinging - less boost is a very good thing!

[Alchemist]

Not that I'm VVTi, or a GTE, but I did have a strange problem of engine loosing power due to the AFR's leaning right out and then the ECU cutting power. Turned out to be the Oxygen sensors giving out slightly dodgy values, which was messing with the AFR's, leaning the engine out and no power, or maybe in your case pinging? To troubleshoot I drove around for a few days with no Oxygen sensors connected, and engine drove considerably better and didn't lean out as the ECU was running uber rich for safety due to the lack of sensors.

I would find a mechanic or a Toyota dealer with the ODBII scanner and the 2JZ-GTE firmware and see if they will take you for a drive to see what error codes they can get, as there are lots more the scanner picks up than what flash through the ECU check light when in diagnostics mode.

You probably know all that, but just chucking my 5c in

If all else fails download the service manual for the 96+ Supra from supraforums.com.au or chuck your GT35/40 question on the US supra site as the yanks do all kinds of silly things.

[Draven]

that's the thing .. my dyno AFRs were pretty much ideal. ~14 at low load, going down to ~11 under boost

[Norbie]

Mr 1JZ: yes it is.

Draven: I'm suggesting it as a diagnostic tool, not a permanent switch. If your engine really is pinging a few test runs won't hurt it, remember you've got the ECU jumping in to save the day before anything bad happens.

If you have a read through supraforums you'll notice a lot of people having problems with the second turbo not coming online, and 9 times out of 10 it's a problem with the sequential system rather than any mechanical issues. The standard way to determine if this is the problem is a temporary switch to TTC mode.

[Draven]

I might grab a few one way valves and test it out then

[Draven]

I have discovered that it's not the second turbo (or I don't think so). I took it for a 5th gear run (on a track of course) and at ~3500rpm (before the second turbo starts to boost) it cut out, so I think it may be load dependant... which points me toward a fuelling issue.
I'm going to try the 12v fuel pump mod tomorrow, see if maybe it's not swotching over from 9v to 12v

[Draven]

well that was all jolly good fun.
completed the 12v fuel pump mod with no dramas at all, and it still hasn't made a difference.

I have just found that if I push it till it cuts on me, and keep the accel down slightly, even to below 4000rpm, it still won't let me boost. I have to let off the accel for 2-3 secs before it will give me back regular power.

[kingmick]

Mr 1JZ: yes it is.

Draven: I'm suggesting it as a diagnostic tool, not a permanent switch. If your engine really is pinging a few test runs won't hurt it, remember you've got the ECU jumping in to save the day before anything bad happens.

If you have a read through supraforums you'll notice a lot of people having problems with the second turbo not coming online, and 9 times out of 10 it's a problem with the sequential system rather than any mechanical issues. The standard way to determine if this is the problem is a temporary switch to TTC mode.

no, but it will find any weak point quick. wether its rings,ringlands,head gasket etc, it will find the weak point! which at times can be better than on a power run!