Jump to content
The mkiv Supra Owners Club

Problems with turbos


jacko

Recommended Posts

I know there are loads of posts about problems with the stock turbos caused by sticking valves etc.... but just wondered if you could help me with my problem. It's not a case of the 2nd turbo not working at all, it works sometiems, and then other times the first turbo boosts and then drops right off. Im guessing it is something to do with one of the actuators, but does this help to narrow it down to exactly which one is causing the problem? Cheers!!

Link to comment
Share on other sites

I took it to a RR day today and the second turbo decided not to put in an appearance, so i really need to get the problem sorted. I would do it myself, but the TT system seems quite complex and i'd rather just let a pro do it. Can anybody recommend somewhere to take it thats not too far from Northants

Link to comment
Share on other sites

I had a problem like this a few years back, it turned out to be a faulty IACV VSV, sometimes the VSV would work and I'd see 0.9bar with both turbo's online but then it would drop down to 0.7, and other times the 2nd turbo didnt come on at all.

 

If you pop outside, start your car then raise the revs from in the engine bay quickly to around 4-5k you should be able to see the actuator move, if it doesnt then this could be your problem :)

 

It's takes about 1min to replace one of these vsv's :)

 

or you could try this to diagnose the problem,

 

http://mkiv.supras.org.nz/articles/andy.htm

 

this thread may help too

 

http://www.mkivsupra.net/vbb/showthread.php?t=49070&highlight=vsv

Edited by Tom (see edit history)
Link to comment
Share on other sites

no it doesnt come online if i let off, ive try dipping the clutch as well, nothing helps. I need to get it sorted, i got 195bhp on the dyno earlier lol

 

Is this the right actuator? If so i'll have a look at it tomorrow. Its only boosting on first turbo atm, so i'll give it a tap and see if the second one shows up

 

Just thought i'd mention, it doesnt sound very loud when the second turbo doesnt work, not like the air is coming thru the exhaust system, more like it's never been in the 2nd turbo at all, if that makes any sense?

 

The boost pressure is going from 7psi on first turbo to 0psi when the second should come on

turbo.jpg

Edited by jacko (see edit history)
Link to comment
Share on other sites

no it doesnt come online if i let off, ive try dipping the clutch as well, nothing helps. I need to get it sorted, i got 195bhp on the dyno earlier lol

 

Is this the right actuator? If so i'll have a look at it tomorrow. Its only boosting on first turbo atm, so i'll give it a tap and see if the second one shows up

 

Just thought i'd mention, it doesnt sound very loud when the second turbo doesnt work, not like the air is coming thru the exhaust system, more like it's never been in the 2nd turbo at all, if that makes any sense?

 

The boost pressure is going from 7psi on first turbo to 0psi when the second should come on

 

i have a second turbo for sale and all the vsv valves if you need em

Link to comment
Share on other sites

  • 1 month later...
Would a dodgy BOV be enough to cause this problem?

 

Yes I spent ages looking for a problem where my 2nd turbo would not kick in , supramatt came round popped off the bov and could blow though it when you shouldnt be able to . I got a screw driver to it to double check and the seal had spilt . Replaced it and good as new.

Link to comment
Share on other sites

well me and robert learnt a lot about the tt set up when we were mucking around on my car. theres a very very small pipe near the bottom side of the turbo which wasnt on, i was getting no second turbo at all as a result of it and everything your saying sounds exactly the same to what happened to me.

turbo.jpg

Edited by adnanshah247 (see edit history)
Link to comment
Share on other sites

I might have the wrong bits of the system here but if you put it into true twin instead of sequential doesn't that remove the VSVs from the loop. Ignore me if you have done this already.

Also whereabouts in northants are you as i have to go to corby/kettering every weekend and i have a stock bov if it will help

Link to comment
Share on other sites

Ye that's where im thinking of going.

 

The problem is intermittent so im wondering if maybe the BOV is sticking open sometimes, or sometimes sticking shut, as the car randomly started chattering the other day, and then stopped again

 

I'll check that first, as its the easiest / cheapest to sort

Link to comment
Share on other sites

Guest supraman582

I had exactly the same problem as u mate with the stock turbos, if you want to get it sorted then check out advancedme.co.uk theyre based in silverstone ask for Dan he sorted mine out no problem.

Link to comment
Share on other sites

It's often the EGCV that causes it (thats the common one anyway). it's sort of centre top in the diagram.

 

Also, a dodgy BOV can stop the 2nd turbo coming online, make sure it's connected up the right way round too! Any change you can post a pic of it?

Link to comment
Share on other sites

Personally i would check the IACV. If the iacv isn't working the 2nd turbo will pre-spool but won't come online. This is quite dangerous as it means you will be overworking the first turbo. After that its time to check the EGCV, if the EGCV isn't working then the 2nd turbo won't be getting any exhaust gas and when the IACV opens all of the pressure will be lost from turbo 1. This is less dangerous as the 1st turbo won't overspool.

 

An easy and quick way to test the VSV's is to do the 5 min ttc mod. All you do is take the pipe from the rail to the IACV VSV out and plug it directly into the IACV actuator (this negates the VSV). Do the same with the EGCV, just plumb the pipe from the vac rail into the EGCV (does the same, negates the VSV). Take the car for a run. If you get full boost then its one of the VSV's. If you don't, its either the pressure tank, the actuators, the valves or the turbo's themselves.

Link to comment
Share on other sites

  • 2 weeks later...

Im still hunting around the engine trying to find the problem. Ive noticed that when i rev the engine the IACV actuator moves (opens or closes?) and then once the revs have dropped down to idle the arm moves back again. Is this right?

Link to comment
Share on other sites

  • 2 weeks later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. You might also be interested in our Guidelines, Privacy Policy and Terms of Use.