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No second turbo :(


Thorin

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Yep, you've named and shamed those components correctly :) How the hell you got that piccy of the EGCV I'll never know - are you a gynaecologist by trade? :eek:

 

Anyway, have a look at the plug going onto the IACV, it's probably just the rubber boot, but it seems to be rotated in a funny way. If it's not wired up, the IACV won't open.

 

The foamy thing on the heater hose should be resting on the plug cover too, sorry, terribly anal, it won't fix your problem but that sort of thing bugs me :)

 

Now, another test is this - The connecting rod goes to a rotating actuating arm, right? And that's spring loaded to make sure the butterfly flap stays closed when the actuator isn't pushing on it. There is a stop point which the actuating arm rests against under said sprint pressure. Make a long thin strip of tinfoil and wedge one end between the actuator arm and it's stop, and bend the tinfoil upwards so that if the arm comes off it's stop, the tinfoil strip will fall away. Now go for a drive and make sure you get above 4000rpm with a large bootful of throttle. After this, check for the tinfoil. If it's still there, the valve didn't open and you have found your problem area...

 

There may be a better way of doing that, but I thought it up when trying to troubleshoot my 2nd turbo not working, and it worked for me - the metal pipe feeding the EGCV was blocked, so it didn't drop it's bit of tinfoil! :)

 

-Ian

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Originally posted by Ian C

Yep, you've named and shamed those components correctly :) How the hell you got that piccy of the EGCV I'll never know - are you a gynaecologist by trade? :eek:

 

Nah, I'm just good at getting into tight holes (but I don't have a strut brace in the way either) ;)

 

Originally posted by Ian C

Anyway, have a look at the plug going onto the IACV, it's probably just the rubber boot, but it seems to be rotated in a funny way. If it's not wired up, the IACV won't open.

 

The foamy thing on the heater hose should be resting on the plug cover too, sorry, terribly anal, it won't fix your problem but that sort of thing bugs me :)

 

Are we on about tight holes again? :D

 

Originally posted by Ian C

Now, another test is this - The connecting rod goes to a rotating actuating arm, right? And that's spring loaded to make sure the butterfly flap stays closed when the actuator isn't pushing on it. There is a stop point which the actuating arm rests against under said sprint pressure. Make a long thin strip of tinfoil and wedge one end between the actuator arm and it's stop, and bend the tinfoil upwards so that if the arm comes off it's stop, the tinfoil strip will fall away. Now go for a drive and make sure you get above 4000rpm with a large bootful of throttle. After this, check for the tinfoil. If it's still there, the valve didn't open and you have found your problem area...

 

There may be a better way of doing that, but I thought it up when trying to troubleshoot my 2nd turbo not working, and it worked for me - the metal pipe feeding the EGCV was blocked, so it didn't drop it's bit of tinfoil! :)

 

-Ian

 

Er sounds like a good idea, I'll try and give this a go a bit later but I'm a bit busy at the moment. If not I'll report back tomorrow.

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Right I didn't get chance last night but I gave it a go this morning. I tried it on both as you suggest. Both of the valves appear to be opening ok (at least to some extent) as the bits of foil fell out after just flooring it up to the end of the road and back. I even stopped and tried it again and once more both pieces had fallen out when I stopped and checked.

 

Any other suggestions? Or am I just going to have to bite the bullet and take it to someone who knows these things better (Chris!!!).

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Check your BOV is ok, if it's buggered it will leak boost back into the pre-turbo intake stream. There is some way of checking it that involes removing it and trying to blow through it, can't remember if it's from either direction or a specific one, have a search :)

 

Beyond that, you need to let us know as much info about the symptoms as possible - what the boost is at what revs, what it feels like, any fluttering, hesitation, misfire, any new noises, that sort of thing. Does it feel like the boost drops again? Does it feel like it's underpowered?

 

-Ian

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Originally posted by Ian C

Check your BOV is ok, if it's buggered it will leak boost back into the pre-turbo intake stream. There is some way of checking it that involes removing it and trying to blow through it, can't remember if it's from either direction or a specific one, have a search :)

 

Beyond that, you need to let us know as much info about the symptoms as possible - what the boost is at what revs, what it feels like, any fluttering, hesitation, misfire, any new noises, that sort of thing. Does it feel like the boost drops again? Does it feel like it's underpowered?

 

-Ian

 

Ok I'll give the BOV a check over when I get chance (will be the weekend now).

 

Well the symptoms are as I mentioned in my first post really. Everything seems normal right up until the second turbo should come on line, then very briefly the boost will fluctuate slightly before settling at 0.65-0.7 again and stays at that up until the redline. No unusual noises, no smoke out of the exhaust (apart from the usual small puff of smoke when you floor it), no misfires.

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I've finished early today but still not had chance to check the BOV and I'm not about to check now as it's pissing it down.

 

Was reading a few threads on Supra forums relating to boost problems and a shafted BOV does sound like it could definately be a likely suspect. I'll list below a few different things that people had mentioned could be the cause of boost problems, perhaps someone could say what the symptoms would be of each and if it could relate to my symptoms?

 

1. Boost leak (for a boost leak this bad I would have irratic idle and black smoke and would probably mean a hose had popped off or split completely?)

2. BOV leaking boost

3. EBV sticking (what is this?)

4. IACV actuator bad

5. VSV to IACV leaking

6. EGCV actuator bad

7. VSV to EGCV leaking

8. Bad actuator to second turbo (not sure if this is just the EGCV or IACV or something different)

9. Pressure tank faulty

10. Wastegate stuck open (would mean very low boost at all times even when just on 1st turbo?)

11. Reed valve (what is this?)

12. Blown turbo (death whine and lots of oil in IC tubing?)

13. Punctured IC (black smoke again?)

 

 

Another thing that may be relavent, on the way home yesterday my mate was behind me in his car with his window open and said that when I accelerated away he could really smell the car pretty strongly. I understand this is unburnt fuel smell and means that it is running rich? I'm presuming this is probably related to the problem. I did notice this smell when I first had it decatted but it wasn't that strong a smell and I just put it down to being normal occurance with removing the cats, but it does definately seem to be worse now.

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Originally posted by Thorin

1. Boost leak (for a boost leak this bad I would have irratic idle and black smoke and would probably mean a hose had popped off or split completely?)

2. BOV leaking boost

3. EBV sticking (what is this?)

4. IACV actuator bad

5. VSV to IACV leaking

6. EGCV actuator bad

7. VSV to EGCV leaking

8. Bad actuator to second turbo (not sure if this is just the EGCV or IACV or something different)

9. Pressure tank faulty

10. Wastegate stuck open (would mean very low boost at all times even when just on 1st turbo?)

11. Reed valve (what is this?)

12. Blown turbo (death whine and lots of oil in IC tubing?)

13. Punctured IC (black smoke again?)

 

I've tried slotting replies into quote blocks before and failed, so I'll number my replies instead :)

 

1 - You would be suprised how well the car can run until you boost it even with a leak. Actually, I once had similar symptoms to the EGCV not working and it turned out that I hadn't tightened the jubilee clips on the small bit of tube between the intercooler hard pipe and the turbo outlet 'Y' pipe! So, again, could be a boost leak somewhere!

2 - Next thing to check IMO

3 - EBV is the Exhaust Gas Bypass Valve. It hangs off Turbo #2 and looks like a wastegate - what it actually controls is the prespool of #2 by allowing some exhaust gas to flow from it's outlet into #1's outlet, thus letting #2 spin up a bit. If this wasn't working, you would get a nasty jerk as #2 got slammed into action from a standing start, so I don't think it's that.

4 - Tried that

5 - Tried that too

6 - And that

7 - Aaaaand that

8 - There is only the EGCV, EGBV, and IACV, you've checked two and the symptoms aren't right for the other.

9 - If it was faulty, the EGCV and IACV wouldn't open.

10 - This would make boost buildup slow, but you would still reach full boost.

11 - The IACV has a reed valve to allow the small amount of boost created by #2's prespool to enter the intake stream (otherwise it would stall the turbo and bugger the prespool function). It's a reed valve to stop boost from #1 entering #2 and spinning it backwards.

12 - If #2 isn't spinning when it comes onstream, it'll get #1's output go backwards through it. Boost will drop to about 0.1-0.3bar and the noise is quite different to normal operation.

13 - For black smoke you would need less air going into the engine than the stock pressure sensor thinks there is, so the leak would have to be *after* the sensor. Pretty much impossible on a j-spec.

 

However, if there is a flap-type leak in the system somewhere that only opens up at a certain boost pressure, it would account for most of your symptoms. The obvious choice for this is the BOV...

 

Phew, that kept me busy for a bit :)

 

-Ian

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Hi again m8

 

Had exactly the same problem as you!

 

Have you double/treble checked the small boost pipes leading to the actuator?

 

Cant show you pic - but follow the small 3mm jobbies from near (under) your bov down and up (this is where mine came off)

 

This will stop the second turbo

 

Sorry if teaching you to suck eggs etc

 

In fact I'm just going to check my hoses again as suffering erratic idling as discribed above (thanks)

 

Cheers

 

Paul

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Thanks for the reply Ian, I'm sure this thread will be useful to anyone with any kind of boost problem in the future now anyway, and I have a lot better understanding of how the sequential system works.

 

Will check the BOV tomorrow. I suppose it's still possible to be a boost leak somewhere, but I spent a good half an hour checking clips and pipes and couldn't see anything, but I'll have another look.

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Guest Usmann A

Thor if you want a MKIV bov,i think I've got one in the garage,well last time I checked,let me know if you want it mate.Its off me dads car...:)

 

 

 

 

Usmann

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Guest Usmann A

Just checked I got it,its the original DENSO item only 40 odd K miles on it.,with 2 big pipes and a one small (discharge pipe)(i think),with all clips.

 

 

 

cHEERS!

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Well, I removed the BOV and I couldn't blow down any of the ends no matter how hard I tried (and I feel dizzy now). I think I'm going to have to admit defeat on this and take it to get it looked at by someone who actually knows what they are doing :(

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  • 3 weeks later...

Well I took it down to CW's yesterday and I'm now a happy man again.

 

The problem was, wait for it.... the baffles in the exhaust breaking up and causing a blockage in the exhaust. Chris yanked out the offending lump of metal and all's fine again. Felt a bit silly when it turned out that it was something I could have probably sorted out myself anyway but oh well, the main thing is that it's working again :)

 

Oh and the exhaust was loud before, but now it's LOUD. Too loud. Not quite, "Why are my ears bleeding?" loud, but too loud nonetheless. Yet more expense! :(

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