Sudden power loss

Hi All

So my Supra today seems to have very low power for some reason, basically it labours off the mark at higher than normal revs to attain any kind of speed - I've had all manner of noises and whistles coming from my CW brakes but other than that no issues, could my brakes be stuck on partially causing this? Any ideas? When the turbos kick in it still provides the jolt of power just like normal but the overall speed is much lower. It's an auto and the car has had a full rebuild so I am wondering if its brakes or if the TC is stuck on limp home mode or something (although I've tried deactivating it and no difference), any ideas? It feels catastrophic but with a rebuilt engine and no warning lights I am assuming brakes can be the only reason?

I'd start by checking all the clamps on your inlet side hosing. That's my only experience of major power loss on turbo cars is when a pipe has blown off or leaking past a loose clamp.

Would the power loss occur pre boost though if this were the problem as its across the board?

Hi All

Just wondered if I could get any more help on this? If there is an issue with the air inlets I will check this morning (just waiting for the world to wake up so I can start the destroyer of worlds....) but could someone just answer, if it is this would the power loss literally be from 0mph onwards or does it only affect the turbo range? My car is being affected right from set off not just on boost and I would say flat out it will do about 80 not 180 (dont worry I havent tried this!). Any help would be appreciated.

Ok as an update I sprayed WD40 on all the air lines, vacuum lines and nothing shows a leak - its an auto and has CW brakes which ever since I put them in have made a whistle/grind sound up to 15mph and then cleared, I took it to the mechanic and one caliper was stuck on and he freed it but the sound returned almost immediately. Is it possible that the brakes are now stuck to the point its making the car labour?

I also took it for a test drive and to more accurately describe it, you put it in D, it then it crawls forward but nowhere near as fast, then as you put the accellerator on it feels like the car is having to use higher revs to achieve the same speed and there's a resistance. This happens all the way up to about 40-50 and where my foot is normally placed to go at 60 the car is doing about 45mph.

Perhaps foolishly I got to a straight at 45-50 and tried giving it more beans and it flew forward like normal, the turbos giving the normal 1.15 (I'm full BPU) and it just felt totally normal shooting up in speed. After this I stopped, then set off, and it was back dragging again at lower speeds.

Am I describing a brake issue here? The only other thing I can think of is the gearbox is on the way out but why can it sometimes shoot off when more power is applied? Surely its brakes, ie sticking/stuck or more severe with them all sticking somewhat?

If it's brakes after you go out, the sticking one will be hot.

Yes check for heat, also when cold if it's parked on the flat, release the handbrake and pop it in neutral (press that red button to move the shifter into N) and just rock it from the drivers door it should roll with not too much effort.

The Supra normally over powers a dragging/stick caliper pretty easily and without people knowing. But you might be more sensitive to it.

Basically go out and drive it normally, does it boost up ok, get the 2nd turbo kick, kickdown etc etc ie does it run normally. If you do that and the brakes are dragging then as above the dragging one will be hot. Fingers to calipers first as that shouldn't be too hot, or even just holding your hand in the air can help you tell......spitting on the disks can work too

It might just be them stuck on that first few yards, give them a firm press and release and see if they clear next time.

Any hint of differential heat and you've potentially identified a sticking brake which is often a stuck sliding pin (but that should have been spotted when the pads were fitted.

So I've tried it in neutral and can push it both back and forth, its not easy and is slightly harder pushing in reverse but I can do it so I am guessing as I'm not Hulk Hogan the brakes are only mildly sticking? Which leads me to believe I may have a failing auto transmission is this the next hypothesis? I've had loads of autos go but they generally either fail immediately or the lower gears get affected first and I would guess this could describe it if the first couple of gears were slipping but the last two are fine hence on WOT its fine? if so for one thing f@#k and for another I guess it's better to have a rebuild with new internals than buy a second hand one that could have starship mileage? I suppose it was inevitable, my car has been (badly) stored for years before I come along, I get it and it needs a full rebuild then restoration underneath, suspension goes, brakes go, so the only thing left which is thirty years old is the auto box.

Has anyone had an auto box go in a Supe and if so am I basically describing the process? I've only got it up to BPU and the standard box can take this load surely? I appreciate its old and I may need to replace it but I take it after this it will be fine at BPU ie sub 450 hp? I tell you this year I feel like I've run over a gypsy.

These things are virtually impossible to diagnose over the internet, Ive seen a box fail but only because a fluid line split and it ran dry. When boxes fail you have a lot of slip then basically lose drive as the clutches burn out

Has the "30-years old" transmission ever been serviced?

Have you checked the transmission fluid level?

Have you inspected the colour/condition of the transmission fluid?

Whatever, fix your brakes first!

Take her to Chris Wilson, ask him to go over the car with a fine tooth comb and put any wrongs right. He is your closest Supra guru. Do it all properly, first time round in one go. Then get your car down to David P and let him teach you how to service your autobox properly and strengthen it.

I genuinely take my hat off to you for trying, but for the love of all that is holy, make sure your working from a solid base to begin with. With this, your bonnet, your boost controller and engine threads you really need to listen to the advice being given.

The lack of replies when you need help are because you refuse to listen and take advice from very knowledgable members. Mike most recently. The guy was giving up his free time and going beyond helpful but you just refused to listen.

Don’t mind me, just passing through. Not looking for an argument but that needed to be said. Sorry dude. All the best, hope you get this sorted

Take her to Chris Wilson, ask him to go over the car with a fine tooth comb and put any wrongs right. He is your closest Supra guru. Do it all properly, first time round in one go. Then get your car down to David P and let him teach you how to service your autobox properly and strengthen it.

 

I genuinely take my hat off to you for trying, but for the love of all that is holy, make sure your working from a solid base to begin with. With this, your bonnet, your boost controller and engine threads you really need to listen to the advice being given.

 

The lack of replies when you need help are because you refuse to listen and take advice from very knowledgable members. Mike most recently. The guy was giving up his free time and going beyond helpful but you just refused to listen.

 

Don’t mind me, just passing through. Not looking for an argument but that needed to be said. Sorry dude. All the best, hope you get this sorted

Hi Frank

No offence taken whatsoever and I totally admit I am not knowledgeable but in my defence I actually sorted the BC and bonnet out by taking advice from you guys on here. Also excuse my ignorance but who is Mike? I got the oldest first generation Supra I could because it was released when I was 18 and I felt a link, I knew it would be the hardest to bring up to spec and I would need to lean on the forum and I do take advice when I can. The brake pads which could be causing all the hassles are Chris Wilson fast road pads , I booked in to have those swapped out for Toyota ones and then when that variable is removed I'll update you all to let you know if it was the problem.

I took the car out again today for a few miles and really listened and felt what was happening and basically the really noticeable fault it has is from a standing start it needs too many revs in first (say 2-25000 to get any speed up and then suddenly frees up to drive normally before switching into second, after which it is largely normal across the board, all gears, both boosts etc., but take it down to a standing start and it drags again in the first half of first gear. So this could very possibly be a brake issue which the car is overcoming or it could be slippage. I've never had a n auto box which had half of one gear slip before it went pop so would most people think its the brakes more than the box? As I say I've taken advice from here and I am getting my brakes looked at first I just wondered whether people agreed it was likely to be the brakes. I've had nearly 50 auto cars in the 24 years I've been driving and my gearbox failures are in early double figures and this does not resemble the beginnings of any of the other problems.

What does it do in first in Manu mode and as David P asked have you checked fluids and condition?

One of the first things I did was a full service including auto transmission change but that was three years ago. Then came the rebuild and in 3 and a half years its done less than 2000 miles because o fall the other problems. Just checked the transmission oil though and when hot its about 1cm above max on the dipstick, guess someone overfilled it when they last took the engine out to fix the problems with the sump. Could this be causing some of the issues? What does 1cm over max translate to, a large overfill or just small? If I put it in 1 position I imagine this is only first gear? I can try this to see what it does if so, but in other auto cars when you put it in 1 it holds first for longer but then switches up anyway, is it jammed in first n a Supe?

A little too much won't hurt it, is the fluid cherry red or dark brown and smelling burnt?

Cherry red, here's a couple of pics and the arrow shows the level when cold

I had slipping when i fitted a mines ECU which was dead or dying. Slipped like mad in 1st and 2nd to point where i had hardly any power. Changing to my original ecu fixed it instantly and it's not been back since. (2/3 years ago)

Bright red pics are attached

- - - Updated - - -

- - - Updated - - -

Sorry I posted the pics twice accidentally

Could be the torque converter . Still very hard to tell without seeing , hearing and feeling

There is waaay too much fluid in that. (At least 2 litres?)

Nevertheless, the colour of the fluid indicates that the clutches are not slipping and the box is not overheating for any other reason.

Trying to diagnose a fault like this from descriptions by un-mechanically minded folk, is a nightmare.

Drop the fluid down to the correct level and if that doesn't magically fix it, take your Supra to someone in the Real World who knows their onions.

P.S. How to read your dipstick here... https://www.mkivsupra.net/vbb/group.php?discussionid=188&do=discuss

(Please note that this link to a Group page will not work if you are browsing with a not-so Smartphone.)

Have you tried ..putting a different set of brake calipers on?

I'm looking for a set of UK brakes to upgrade but not sure if they will fit with my wheels, had no problems at all before I upgraded the pads to the CW ones though so maybe my calipers just dont like it. I can drop the level down on the fluid I guess there's a drain on the bottom which I am sure I can find and see what happens then and then when I flip back to Toyota pads maybe it will all be ok hopefully. Thanks for everyone's help so far.

Just a thought but whats the best ATF for my box? I'll get some in for when I'm draining this weekend as I would have thought if I drain too much it's better to put in new than used? I know its Dexron III but any particular make? Also mine says T-II on the dipstick I assume this means something else related to the Japanese market and I should ignore that?

Just a thought but whats the best ATF for my box? I'll get some in for when I'm draining this weekend as I would have thought if I drain too much it's better to put in new than used? I know its Dexron III but any particular make? Also mine says T-II on the dipstick I assume this means something else related to the Japanese market and I should ignore that?

Get it from a Toyota dealer if you wish.

https://www.mkivsupra.net/vbb/showthread.php?56684-FAQ-Oil-Fluid-Interval-Capacity-Steering-Brake-Coolant-Diff-Engine&highlight=fluid

https://www.mkivsupra.net/vbb/showthread.php?92098-Auto-box-fluid-change-on-MKIV-com&highlight=fluid