Turbo producing 0.4bar boost???

I have already posted this up under thread 'snapped bolt fitting 1st decat' http://www.mkivsupra.net/vbb/showthread.php?t=176699 ...but i'm pleased to say that problem is sorted

For anyone who hasn't read my previous thread this is basically what happened...I was fitting my 1st decat pipe when one of the studs snapped inside the turbo elbow so i had to leave the 1st cat in with the cat back exhuast attached until I figured out how i was going to get the stud out.

When i was driving home from work i wasn't even thinking and was going a bit hard on the by pass and then there was a sudden loss of power and a puff of smoke out the exhaust...then the boost gauge showed that it had hit just short of 1.3bar...there is no smoke now but the car hardly has any power at all. I have a restrictor ring etc I was going to fit when i was fitting the 1st decat but obviously this wasn't in at the time as the 1st cat was still fitted. It was only at 1.3 bar for a few seconds...would this be enough to damage the turbos?

I got the elbow off and got the stud removed and assembled the exhaust back up with decat and restrictor ring.

Disconnected the battery for a while to reset ECU and incase it was anything to do with my Greddy BCC. Started the car and let it sit to warm up, took for a drive still not boosting above 0.4bar and when i came back i noticed there was a small bit of oil where it was originally parked....could this be anything to do with the problem i'm having?

I have been told to check all VSV's/hoses etc and am going to tonight.

Does anyone have any other ideas as to what it could be?

Could it be the turbo itself that is knackered? I was under the impression that if the turbo was knackered then it would be smoking out the exhaust while driveing, which it is not.

Any advice would be appreciated

i had been in the same boat, maybe the boost control needs to be tweeked abit, when it snowed my boost was spiking and it felt like the car was juddering when going into second turbo, got it tweaked to normal, and it runs good like it did before, if the turbo's were knackered smoke would come out the exhaust while driving and it would be black, or you have gotten used to the power now.

I always get mine checked anyway.

i had been in the same boat, maybe the boost control needs to be tweeked abit, when it snowed my boost was spiking and it felt like the car was juddering when going into second turbo, got it tweaked to normal, and it runs good like it did before, if the turbo's were knackered smoke would come out the exhaust while driving and it would be black, or you have gotten used to the power now.

 

I always get mine checked anyway.

I thought it was white smoke I should be looking for?

It's nothing to do with getting used to the power mate...the things barely moves lol...absolutely no power. Feels like its gonna go but doesnt give anymore than 0.4bar at a push

I thought it was white smoke I should be looking for?

 

It's nothing to do with getting used to the power mate...the things barely moves lol...absolutely no power. Feels like its gonna go but doesnt give anymore than 0.4bar at a push

sorry white smoke should be billowing out like crazy, black smoked if your car is screwed, have the boost control tweeked abit then, if not the boost then i have no idea mate, get it checked all over.

Intercooler hose popped off or split?

Intercooler hose popped off

Thats what I would go for. Happened to me when I first went bpu. Fortunately for me it was the one connected to the throttle body, so nice and obvious.

Have visually checked all vac hoses and VSV's(don't know how I can check without having a working replacement)

Have stripped it down and removed the turbo heat shield....can't see anything obvious that would be causing this problem

Anyone any suggestions? Don't want to be removing turbos unless i've checked everything else

There is two black hoses/pipes on the induction side of things. About 1.5" in diameter and 3" in length, check those for tears.

Have removed the following and am going to check for continuity

Exhaust Gas Control Valve VSV

Waste Gate Valve VSV

Exhaust Bypass Valve VSV

Where abouts is the Intake Air Control Valve VSV?

Intercooler hose popped off or split?

My moneys on ic pipe popped off or come loose.

My moneys on ic pipe popped off or come loose.

100% sure it isn't the intercooler mate that was the first thing I checked

100% sure it isn't the intercooler mate that was the first thing I checked

Cool , mine did almost the same - wouldnt make over 0.5 bar , the pipe at the IC had come loose . It felt fine to me but upon closer inspection by Martyn it was very slightly loose.

Made a hell of a difference.

Good luck finding the problem

Checked for continuity in the VSV's and the results were as follows

90910-12127 - 41 ohms

90910-12114 - 40 ohms

90910-12126 - 40 ohms

*90910-12115 - 0.76 M ohms*

The one with the high resistance is either the Exhaust Gas Control Valve VSV or the Waste Gate Valve VSV (there are two joined together by a bracket - it is one of these). Does anyone know which one this part number is?

Also phoned Toyota for a price on a replacement and they didn't recognise that part number...have the part numbers changed?

Looks like its the wastegate VSV judging from pics I have seen on here. Whats the part number of this as Toyota don't recognise 90910-12115?

Also here's a few photos if anyone can point out anywhere else I should be checking...I have taken a photo inside the intercooler pipe...looks like theres quite a bit of oil in there...could this be caused by a faulty wastegate VSV?

This wastegate VSV is proving difficult to get a hold of

A bit of oil is nothing to worry about mate best off asking one of the traders on here for a replacement vsv

Assuming it's a j-spec, if the turbos let go or an intercooler hose pops off, it'll still fuel correctly so you won't get black smoke (unburnt fuel).

I also doubt it's your wastegate VSV as even if it was locked fully open you'd still get full boost on the first turbo and then full boost on the second one as well, albeit it would achieve that more slowly than if the wastegate system was working properly. The wastegate would creep open as boost pressure increased, you see.

What you haven't said is what it behaves like on the first turbo? If you get 0.4bar regardless of revs I'd say it's a hose pop-off. If you get full boost on #1 and then it drops to 0.4bar on #2, it's an actuator issue.

-Ian

Theres no smoke coming from exhaust at all.

I don't know if its locked fully open of fully shut.

I've got a replacement coming next week so if that doesn't fix it then i'll take it from there.

Is pulls a little bit on turbo 1 (0.4bar) but then as the revs increase upto and beyond 4000rpm...there is no increase in boost what so ever

Assuming it's a j-spec, if the turbos let go or an intercooler hose pops off, it'll still fuel correctly so you won't get black smoke (unburnt fuel).

 

I also doubt it's your wastegate VSV as even if it was locked fully open you'd still get full boost on the first turbo and then full boost on the second one as well, albeit it would achieve that more slowly than if the wastegate system was working properly. The wastegate would creep open as boost pressure increased, you see.

 

What you haven't said is what it behaves like on the first turbo? If you get 0.4bar regardless of revs I'd say it's a hose pop-off. If you get full boost on #1 and then it drops to 0.4bar on #2, it's an actuator issue.

 

-Ian

Sorry for my ignorance, what is a VSV?

Sorry for my ignorance, what is a VSV?

Vacuum Switching Valve

Have replaced the wastegate VSV and 1st turbo is boosting to 0.75bar now. Doesn't boost any higher on the 2nd turbo...when I lift off the dump valve goes and then there is a strange noise as if the 2nd turbo is dumping all its pressure(mate said its called a death whine)...guessing the 2nd turbo is knackered?

Have replaced the wastegate VSV and 1st turbo is boosting to 0.75bar now. Doesn't boost any higher on the 2nd turbo...when I lift off the dump valve goes and then there is a strange noise as if the 2nd turbo is dumping all its pressure(mate said its called a death whine)...guessing the 2nd turbo is knackered?

Anyone any ideas???

Hi folks anyone any ideas on this issue, ive been helping sean with this for the past couple of weeks and its getting to be a PITA. As seans explained whats been done so far i wont bother, but vasically it building boost easily till 0.75bar then when the second turbo should be coming online nothing the boost drops off and if you lift off the throttle the bov goes followed by a deep wooowing noise.

After searching through the forum for 2nd turbo problems etc it seems like no one has any luck or they just fail to share what there problem was once its fixed ive also read the threads on the sequential system an how it operates to make sure i understand it and the only things ive came across that are any help are....

Problem 1: I don't get a 2nd turbo rush, it just seems to sit at 0.8bar.

The second turbo isn't kicking in. This usually means your IACV isn't opening - the turbo is trying to spin up but can't flow any air, so #1 turbo does all the hard work.

By the time #1 turbo is producing 0.8bar at 5000rpm it's way beyond it's efficiency map and is overheating the air and overspeeding the turbine. Try not to do this too often.

Problem 2: I don't get a 2nd turbo rush, and as soon as I should it dumps all boost instead.

The IACV is opening but the second turbo isn't spinning. All the air boosted by #1 turbo now has an easy path back to the non-pressurised side of the turbos via a non-spinning #2 turbo. In effect, it all goes 'backwards' through #2 instead of going into the engine. You'll maybe see .2 or .3 of a bar of boost but that's about it.

This usually means the EGCV isn't opening. The turbo can't spin as it has no exhaust gas flow path. Although annoying, this won't do long-term damage as #1 turbo won't generate much boost because the engine loses a lot of power, so no overspeeding or overheating.

Any help at all would be greatly appreciated as i want this supra out of the way so i can get on with my car

Cheers

Ryan

Hi folks anyone any ideas on this issue, ive been helping sean with this for the past couple of weeks and its getting to be a PITA. As seans explained whats been done so far i wont bother, but vasically it building boost easily till 0.75bar then when the second turbo should be coming online nothing the boost drops off and if you lift off the throttle the bov goes followed by a deep wooowing noise.

 

After searching through the forum for 2nd turbo problems etc it seems like no one has any luck or they just fail to share what there problem was once its fixed ive also read the threads on the sequential system an how it operates to make sure i understand it and the only things ive came across that are any help are....

 

Problem 1: I don't get a 2nd turbo rush, it just seems to sit at 0.8bar.

The second turbo isn't kicking in. This usually means your IACV isn't opening - the turbo is trying to spin up but can't flow any air, so #1 turbo does all the hard work.

 

By the time #1 turbo is producing 0.8bar at 5000rpm it's way beyond it's efficiency map and is overheating the air and overspeeding the turbine. Try not to do this too often.

 

Problem 2: I don't get a 2nd turbo rush, and as soon as I should it dumps all boost instead.

The IACV is opening but the second turbo isn't spinning. All the air boosted by #1 turbo now has an easy path back to the non-pressurised side of the turbos via a non-spinning #2 turbo. In effect, it all goes 'backwards' through #2 instead of going into the engine. You'll maybe see .2 or .3 of a bar of boost but that's about it.

 

This usually means the EGCV isn't opening. The turbo can't spin as it has no exhaust gas flow path. Although annoying, this won't do long-term damage as #1 turbo won't generate much boost because the engine loses a lot of power, so no overspeeding or overheating.

 

Any help at all would be greatly appreciated as i want this supra out of the way so i can get on with my car

 

Cheers

 

Ryan

Similar to the issue i have/had. I've taken off all of the VSV's and tested them etc, etc. My car is off the road just now and i've just changed every vac hose and i'm in the process of switching the intercooler hardpipes so i'll subscribe to this and post any findings of my own.

if it helps i removed all the turbo pipes from the 2nd tubby and found it to be spinning freely. My symptoms are that i get tubby one spinning up, when tubby 2 should come online the boost pressure drops to just above 0.

I get a funny noise when letting off boost also, so it seems they are related. Its like a whirring wooshing farting noise all in one lol.

You probably have seen this, but just in case.

http://www.mkivsupra.net/vbb/showthread.php?t=35926