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The mkiv Supra Owners Club

A tale of two turbos... advice needed!


IceMan

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Whew, finally signed up for this forum... welcome back me! On to my story...

 

A few months ago after doing a 500 mile round trip I noticed the first turbo on my standard auto TT Supra (standard except for alloys/turbo timer/derestriction) was making a sad whining noise instead of a sharp whistle. Shortly after I discovered turbo 2 didn't seem to be doing anything at all. :(

 

Toyota took a look and confirmed the turbos were broken. This was annoying as the car has only done around 50,000 miles and the air filter is intact, so something must have snuck through to break them from somewhere!

 

After a short delay (due to a front puncture combined with a wheel lock that took replacement 5 wheel lock keys to remove!) I got the car down to Alan Jeffery's (the Turbo Technics dealer in Plymouth - http://www.enginetuner.co.uk). Turbo Technics confirmed both turbos were shot and refurbished them (just over £1400). I picked the car up and tried the results...

 

Turbo 1 is now whistling again (more of a muffled whistle but I assume this is because the new blades probably aren't ceramic like the original ones!). However after that things get confusing. Turbo 1 reaches it's high pitch point (presumably where turbo 2 should engage) and the whistle tone drops briefly then picks up again. Turbo 2 seems to be doing something as the car accelerates more rapidly thereafter (with consistant accelerator pressure) but the old "whoosh" of turbo 2 is still absent (as it was when the turbo was broken).

 

I also still get an occasional "ooo" sound (a bit like the turbo death whine) from the LEFT (i.e. non-turbo side) of the engine when low in turbo 1's range as I accelerate not too hard. Another (new) sound I have noticed is an occasional crackling gravel sound from the top centre of the engine when accelerating hard (which sounds a bit like the noise when you tap the charcoal cannister).

 

I took it back to Alan Jeffery and we stuck it on the rolling road but the results were... inconclusive. Despite 3 guys sitting on the boot lip my massive 265/35 ZR18 Goodyear Eagle F1s kept riding up the rollers trying to escape! So horsepower output could only be rated at 240bhp without the car making a break for freedom! Checking the turbo pressure said the turbos were on 10psi(?) which is standard stock(?) apparently.

 

So given all this, does anyone have any advice/things to check/tests to perform (note I am not an engineer!)? Also, who is now the nearest Supra expert closest to Devon (I asked this 2 years ago but things might have changed since then)?

 

If it would help I could tape a digital dictaphone into the engine bay to record these sounds if it would aid diagnosis...

 

Thanks in advance if anyone can give any advice!

 

Ice

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Thanks for the offer, I'm in the North Devon region, not too far from Barnstaple. Whereabouts are you?

 

Would your car sound different as it has a few more "toys" than mine? Mine's a 1993 so it's the same era as yours.

 

Ice

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:D

Down near Liskeard so a little bit farther than I thought.

Let me know if your coming Plymouth way; although mine has non std induction should sound same on turbos!

 

do you get a noticeable power surge at 4000 rpnm as 2 comes in or no?

Fifty

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I would suggest that you need to find a proper dyno which can take a Supra...I'm surprised that your dyno had so many issues when I've used one only rated to 360bhp (they strap the cars down) the supra didn't budge or out run the rollers.

 

You should get a dip in power at about 3.6-4k rpm as No.2 is fed air to spool it up. After that it should go off like a rocket again.

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I did a little acceleration in 1st earlier today (auto box remember!) and noticed there is a pull in turbo 1, then a lull (where the pitch of turbo 1 dies away briefly) before another pull which I assume is turbo 2... then I got near the redline and backed off!

 

So it seems turbo 2 is coming in too late??

 

Still unsure/not happy about the frequent "ooo" sound in the left of the engine bay when accelerating gently in 3rd (D), auto mode as 1st turbo runs...

 

Ice

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I'm running stock everything, so whatever that should be!

 

These problems are annoying - I'm looking to sell the car not too far in the future (well it is 11 years old so I'd prefer a newer one!) and all these expensive issues hitting late in the day isn't fun!

 

Ice

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