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The mkiv Supra Owners Club

boosting trouble.


mellonman
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firstly i dont mean to upset any n/a guys.:taped:

ive had this problem for a while and not sure wot it is

 

if im going along and put my foot down and kick down into a gear which is of around 5000rpm you hear alot of engine but little boost 0.3 bar all the way till 6000rpm.

this doesnt happen every time so havernt been that botherd just wonderd if any body had ever herd of this

i have an apeci avcr and front mount and hks pannel filter:)

carnt remember if it done it before the avcr

 

can anybody help?

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There are a few posibilties here..

 

If you hold it in say 2nd or 3rd gear at 2000rpm and take it up to ~5500rpm, what boost at you seeing through this range? For example, does it start building to 0.5bar at 3800rpm then start dropping down again?

 

Any sign of black smoke from the exhaust?

 

Does it idle okay?

 

Are the plugs fouled?

 

If you can find that out it should help identify the cause. I think I know what this is (EGCV sticking).

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it idles just fine,if i build up boost through the revs its fine,only happens if it kicks down into 5000 or more and not every time then, even standard boost it does it could it be my avcr duty valve sticking?:search:

 

Just to confirm: If you take it thought the rev range it's build boosts correctly, if you kick it down from cruise (sub 4000rpm) to say 5000rpm (where both turbo's should come online) it povides very low boost?

 

If thats the case then we know the cause.

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yeah that does seem the case i do hope its good news:innocent:

 

It's highly likely to be a sticky EGCV, it's popping up more and more in the last year or two (though has been a regular issue for people since before I joined).

 

It's not easy to fix, there's a recent thread in tech with more details: http://www.mkivsupra.net/vbb/showthread.php?t=146357

 

PS: It's not a good idea to keep your foot down while the 2nd turbo isn't engaged once rpm gets over 4500rpm. It'll overspeed the first turbo with the potential for a failure.

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thanx for all the help:)

it doesnt happen that much by the sounds ov it ill wait till its terminal.:taped:

sounds expencive

maybe should give the lead foot a rest:d

it is only if i drop 2 gears after all, but it is a auto so unpredictable at times does wot it wants to do

when it happends i wont keep my foot down and hopeing for the best:)

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As mentioned already, if it does happen take your foot off the throttle and re-apply, it should kick the valve open again.

 

If you keep your foot applied it'll eventually blow the first turbo or cause bore wash. The 2nd one being the most serious as it means a new engine.

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sorry hommer

i havernt tryed taking my foot off.before my 2nd de cat it wouldnt get the boost at all but now that cats gone it gets boost arfter a bit

but still not right away

with foot down

would it help if i took first cat out or just more trouble:search:

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