Gone BPU...now have low power

ok, please bare with me here as im no mechanic and its a bit long winded...

I recently installed both decat pipes and a restrictor ring on a 95 TT J-spec before X-mas. I reset the ECU and took car out for a spin, gently at first then with some spirited hard pulls.

I found that the car was pulling strongly, felt strongler then before but that the boost was peaking at 0.9 bar which I think is about standard. I jumped on here, did some reading and found that other people have had similar problems and that it was possible that the RR might need boring out by a few mm. No big deal so I left that for the time being and then installed a walbro fuel pump and a TRL fuel cut defender, couple of hours later, another ECU reset and went for another spin.. RED TRIANGLE OF DOOM after 10-15 mins. Car was driving and sounded fine, so I checked the FCD which was fine, but found a loose wire leading up behind the dash. took dash out and found a broken connection on the Speedo converter/delimiter which I soldered in. retested and presto Warning light is now gone. However the car now feels low on power in the lower gears, I have to have 4k+ revs on to get any sort of power in 1st,2nd and 3rd. Response is better at speed, so when on motorway etc 5th 6th gear seem to responde better, boost is strong when you plant the right foot. Im stumped as to how ive caused this.... Any ideas??

Have you tried to reset the ecu after the red triangle fix?

dunno about your 2nd issue realy, maybe a pipe off somewhere or the first turbo is knackered? but ive never seen the first one go. im no mechanic ether

. but id leave the restrictor ring as it is and if you want to up the boost use a boost controler. expanding the rr could run you into troubles later

Take it to someone who knows supras,

To be fair i think you have tried most things. You shouldnt be losing power.

I was under the impression that the J-spec didnt need a Boost controller to up the boost to 1.2 bar, I thought that was the whole point of decating and installing the RR...

I have new Plugs going in shortly, colder range and ive had a look under the bonnet and cant find a popped pipe or leak...

You can hear the 1st turbo kick in at just under 3k revs but theres no power increase that i can notice.

Cant remember if I reset the ECU that last time, so I will do that once im home today but wouldnt of thought that be the issue with it being so specific to the lower gears....

Have you inadvertantly set up the electronic TTC mode? I have no idea how you do TTC with wires but I'm betting it's in the same set of ECU connectors as the FCD?

the FCD is wired into the ECU as per the diagram I found on this site which also matches the wiring diagram that it came with. Obvisouly ive no way of knowing if its duff though as the car isnt boosting above 1 bar to hit fuel cut...

Im none to sure on this TTC mode as ive never really lucked into it. wouldnt the power still be exceptable though (decent response at 2-3k revs as aposed to the slow crawl im currently getting). Is this possibly a slippy clutch, flywheel? im clutching at straws here btw.

How much boost you see before ~4000 rpm?

wouldnt the power still be exceptable though (decent response at 2-3k revs as aposed to the slow crawl im currently getting).

Nope, it'd be pants boost below 4K.

How much boost you see before ~4000 rpm?

Ill have to check once I get out of work for dinner in an hour or so.

Tbourner, i dont thing I have explained myslef very well:

Quote:

Originally Posted by ulysses31

wouldnt the power still be exceptable though (decent response at 2-3k revs as aposed to the slow crawl im currently getting).

Nope, it'd be pants boost below 4K.

What i was trying to say, is there should still be some response/power between 2-4k revs surley...its as if theres no progression in power at all unitl the tubos kick in, so it feels a bit like drastic T- Lag . Im getting quite tired of people looking at me like im some kind of chav, revving the nuts of my car for fun when in fact its because unless i have my foot planted im struggling to pull away from traffic lights or junctions . Its not exactly a quiet car to begin with lol

Could it have to do with the type of fuel cut defender you're using? I heard something like the Greddy works better than the HKS, but why I don't know. Somebody?

Take it to someone who knows supras,

 

To be fair i think you have tried most things. You shouldnt be losing power.

If im unable to find a solution to this myslef, where is the best place/s to take this around south yorkshire?

Check that boost, because IF you don`t get boost before 3500-4000, reason is that turbo 1 wont make any boost :d:d:

Maby...

-IACV stuck open?

-EGCV stuck open?

So, if it started after you installed fcd, i think you should check wirings, maby you have somehow messed ecu wiring = forced iacv or egcv open, valves are controlled via ecu (12v).

It sounds from your description that the 1st turbo is not coming on line or both turbos are spooling up in parallel ie. giving you more turbo lag. Do you have a boost gauge fitted? If the turbos are running sequentially you should start to see positive boost at around 1800rpm, the boost should rise to around 0.6-0.7bar, you should then feel the second turbo come online at just over 3K+ rpm.

It could be that the car has been electronically converted so that the turbos run in parallel ie. TTC (True Twin Conversion). It could be that the wire you reconnected has caused this, I would try disconnecting the wire you soldered and see if it spools normally again.

You mention possible clutch slip, if the clutch is slipping you will see/hear the revs rise faster than the car accelerates, ie. it will feel like the engine is not properly connected to the gearbox/wheels, which essentially it isn't as the clutch between the engine and gearbox is slipping.

Heckler will be able to tell you which wire it is that causes the TTC mod.

 

You mention possible clutch slip, if the clutch is slipping you will see/hear the revs rise faster than the car accelerates, ie. it will feel like the engine is not properly connected to the gearbox/wheels, which essentially it isn't as the clutch between the engine and gearbox is slipping.

Thanks Nic,

I think what you've said above more accuratley describes the feel of the problem. The revs are going through the roof, the turbos are comming in and by the time the added kick is applied, the car is finally collecting speed. Would it make sense then that the was less noticable when already at speed ? I.e seems to be less of an issue in 4th,5th and 6th.

And the big question (not jumping the gun yet).. GULP... how much is a new clutch for a J-spec TT???

Get an uprated one. IIRC my RPS street was about £600 fitted.

//edit: IF that's the problem - obviously - don't go changing it until someone has confirmed.

Thanks Nic,

I think what you've said above more accuratley discribes the feel of the problem. The revs are going through thr roof, the turbos are comming in and by th time the added kick is applied the car is collecting speed. Would it make sense then that the was less noticable when already at speed ? I.e seems to be less of an issue in 4th,5th and 6th.

Definitely sounds like the clutch in that case. Yes the clutch will slip more in lower gears. If it is slipping do not drive it, a slipping clutch generates a lot of heat which could damage the flywheel if it hasn't already.

And the big question (not jumping the gun yet).. GULP... how much is a new clutch for a J-spec TT???

Hopefully if the flywheel is ok you will just need new clutch cover, clutch plate, and release bearing, I would fit genuine Toyota parts.

I just want to thank everyone for there input so far, responses have been great.

Ive got a few things to work with now and will get the car looked at shortly in regards to the clutch. Unfortunatley this is a daily driven car and its been driving this way for a couple of days now. so I will prob need a flywheel as well but I'll see what the garage has to say about that.

Can I just confirm that a standard toyota clutch is fine for BPU? or should I infact go for an uprated one ? I dont intend to go beyond BPU anytime soon.

thanks

Lee

Can I just confirm that a standard toyota clutch is fine for BPU? or should I infact go for an uprated one ? I dont intend to go beyond BPU anytime soon.

A standard clutch will cope at BPU levels.

If you want a clutch with a bit of extra 'bite' drop Chris Wilson an email as he supplies a modified one.

Here's the info on my clutches. If the existing clutch is slipping badly enough the engine won't load up enough in low gears to produce much boost at all. The boost problem may well be clutch related as well.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I use the stock, brand new driven plate, as it is correctly

balanced, doesn't judder and will hold all but mega torque

highly modded engines or cars used for drag racing.

I modify a stock brand new cover to give more clamping force.

The reason I tooled up to do these is some of the aftermarket

US clutches I have fitted SEEM to be built from used cover

assemblies with reground friction surfaces, and a stronger

spring. I have had hellish trouble getting these to fully

release, because due to this seemingly thinner cast iron

friction face, the geometry of the clutch goes to pot, and

being a pull type clutch (the hydraulics pull the bearing

away from the engine, rather than the more normal push type)

it is a lot harder to effect a cure.

For 455 pounds plus VAT , you get a brand new driven

plate, a brand new modded cover, and a brand new release

bearing. I would rather fit myself so any complaints are down

to me, I see a lot of clutches damaged by people without the right gear

(a ramp and transmission jack, plus correct circlip tools and fitment)

or clutches fitted to patently *uggered flywheels. I will do a supply

only if you feel competent to tackle the job or are using a bona fide garage to

fit the clutch

Toyota use a dual mass flywheel (the flywheel is in 2 parts, an inner and

outer assembly, damped in the middle) which is now showing signs

of wear causing a lot of rattle when idling or on very light

throttle openings. For God knows what reason they are charging

about £270 + VAT for a new one, they look more like they should be

over 500 to me, but don't say anything :-) The very similar LUK dual

mass flywheel on Maseartis is nearly £1000 + VAT.... So if the flywheels

old enough or abused enough to be scored it should be replaced.

Fitting by myself will cost £175 + VAT.

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