Help : 2nd turbo gone?

[Guigsy]

Ive seen this http://www.mkivsupra.net/vbb/showthread.php?t=252

 

But it doesn't relay answer my questions. Im quite sure whats going on but i want to check.

 

Monday. I go to work. Don't use 2nd turbo on the trip. I go out for lunch. Floor it up the slip road to the dual carriageway, 2nd turbo comes on just fine. I carry on and eat my lunch and come back to work. nothing out of the ordinary at all. I head home after work. Give it some beans, again 2nd turbo is fine.

 

Headed out after i get home (mrs wanted to go to hobbycraft) didn't use 2nd turbo but didn't notice anything out of the ordinary.

 

Came to work this morning. Nothing wrong. Headed out for lunch all it still fine. Give it some beans on the way home. Car kicks down. first turbo is fine. whistles away and gives normal boost. Then when im expecting 2nd turbo there is nothing. Still nothing... Still nothing, Then it hits red line (or it almost does) and changes up. No strange noise. No smoke. Nothing at all that i would expect if a turbo was knackered.

 

Pulled over turned car off. couldn't see anything wrong. carried on back to work. Gave it a few more boot fulls but i cant see anything out of the ordinary other than that the 2nd turbo appears to have gone on holiday.

Boost for 1st turbo is fine, about 0.6 bar ish and it stays steady on that all the way through the rev range. AFR's and EGT's all look normal.

Had a look under the bonnet and i cant see anything that's come undone. Although i didn't have time to scrabble around under the car.

I think (hope) its probably just a pipe somewhere.

Its definitely not an IC pipe as iv had that before.

 

Ill have a further look tonight and probably book it into the garrage tomorrow anyway as its due a service (and a tyre) before suprapod.

[Dnk]

Have a look at the IACV VSV, mine lost the second turbo the other day and it was the vac pipes that had come off.

Edited July 6, 2010 by Dnk (see edit history)

[Scott]

Another VSV to check out is the one directly in front of the 1st turbo. I think it is the EGCV. Mine popped off the manifold pressure side at 1.2bar due to an ill fitting pipe, it was fine at 1bar, and I was left with no 2nd turbo.

[hodge]

well my moneys on a pipe came off the pressure tank under the plenum.

[Guigsy]

place your bets people.

[nigelboyne]

if you got no smoke or whine should be a small hose i cable tied and metal clamped them all to stop this happening now 1.4 bar/1.5 bar is safe from leaks

[Scott]

If you can't see any of the vac lines disconnected, and definitely no splits, then I would go with Hodge and say the pressure tank.

 

An easy way to check this is to pressurise the system. Simply put it into the temporary TTC mode. Give it a bit of a boost then open the boot and see if the actuators are still open. If they are then the pressure tank is fine.

 

You should also get the 2nd tubby kicking in, giving full boost, in TTC mode too. This is a pretty good way of telling if the 2nd turbo is fooked.

 

To totally rule out the pressure tank you need to hold the actuators open with force (the TTC actuators). I just jammed something under them to stop them closing and took the car for a run. Again you should see full boost. If you don't, chances are it is the 2nd tubby.

[AJI]

Or failing the above options then it could be a leak in the intercooler or piping.

A split hose or a leak in the system can sometimes present itself only at high enough boost levels, ie. the split/leak is always there but allows 0.6bar of pressure which would seem as if everything is normal for 1st turbo use.....but then as the pressure builds the split/leak will be forced open and it will feel like no 2nd turbo.

 

This happened on mine not too long ago; I had a crack in the intercooler which made drving feel normalish on 1st turbo, but boost would not rise above about 0.7bar (or there abouts). With thanks to Scott M i got it sorted in the end.

[Guigsy]

On the way home from work all was fine... Very odd.

[Homer]

Sticking EGCV possibily, that can cause the 2nd turbo to not engage, but it will normally come back online after lifting off and re-applying the throttle.

 

PS: It's not a good idea to run the car at high rpm with only the first turbo operating, it'll put a huge amount of pressure on the turbo. If the 2nd turbo doesn't engage, best to lift off and let it change up.

[pistonbroke]

Homer is right. My money is on that VSV.

[Dnk]

check for a fault code, it could be the actuator as said above, i had this and then it was fine, its code 34 if it is

[Scott]

On the way home from work all was fine... Very odd.

 

If it is now OK one of the actuators or VSVs definitely stuck as suggested.

 

Could be a short in the VSV down to a faulty VSV down to an actual sticking actuator. When I blew my 2nd turbo by putting in too much boost my EGCV actuator itself stuck in place (due to the actual amount of pressure). I had no pressure at all until I released it as the pressure from tubby 1 was escaping right through my blown tubby 2.

 

I wouldn't be surprised if it becomes a very intermittent fault. Fingers crossed for you that it was just a one off if it is the actuator though as that is an absolute NIGHTMARE of a job, clearly swapping the VSV over is a canter

[madwoody1]

guigsy

did you get this sorted as my supra is doing the same as yours

[madwoody1]

bump

[Scott]

bump

 

You have followed all the advice/avenues of the thread? Your findings from it all?

[madwoody1]

well dont the ttc mod and both turbos coming on

now that i've stopped the car and had a look at the actuators they are both holding open

so i think that

means pressure tank is ok?

turbo no.2 is ok?

so think that would mean it is a solenoid of some sorts that control the actuators?

[Andy Blyth]

well dont the ttc mod and both turbos coming on

now that i've stopped the car and had a look at the actuators they are both holding open

so i think that

means pressure tank is ok?

turbo no.2 is ok?

so think that would mean it is a solenoid of some sorts that control the actuators?

 

I've had exactly this behaviour before. It turned out on mine to be the IACV VSV solenoid had failed open circuit.

 

You can check this on the car by removing the connector and using a multimeter (most cheap ones should be OK) to measure the resistance between the two pins of the VSV. From the repair manual, you are looking for something in the range of 38.4 to 44.5 Ohms measured at 20 degrees C.

 

Worth a try, it's a quick check.

[madwoody1]

will try that next being as i'm an electrical engineer should have one or two multi-meters laying about thanks andy

[Dnk]

I had the same problem, check for fault codes, mine flashed up 34 which is as below.

 

Mine actually was a very easy fix as i'd just popped the vac hoses off

Edited August 8, 2010 by Dnk (see edit history)

[Scott]

well dont the ttc mod and both turbos coming on

now that i've stopped the car and had a look at the actuators they are both holding open

so i think that

means pressure tank is ok?

turbo no.2 is ok?

so think that would mean it is a solenoid of some sorts that control the actuators?

 

 

Yup spot on.

 

Sounds like something as simple as a VSV then. Can you borrow a couple to try them? IIRC it has to be down to one of the ones you bypassed to try the TTC

[madwoody1]

right the thing is now i've done the ttc mod i'm thinking shall i leave it like it is?

is there any thing that can go wrong leaving it like this?

[Scott]

The fueling isn't spot on for the tubby's running in parallel at the transition stage. It will also run a fair bit rich at the lower end of the revs because the ECU expects to see boost from the 1st turbo.

 

I ran it for a while with nothing going wrong. AFR's were OK for me.

 

If you want to leave it like that I would suggest getting an AFR if you don't already have one. Just to keep an eye on the fuelling