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The mkiv Supra Owners Club

Aftermarket ECU On BPU


terribleturner
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Why would an aftermarket ECU make any difference on a BPU car?

At best it will be as good as the stock unit. Eliminating the MAF won't give any dramatic gains either.

 

Now if you've got a fancy single, different cams etc, that's a different story...

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I wondered this, but Dimitri said that the power and the feel is really noticable, plus the MPG is much better. No idea myself :shrug:

 

 

They probably had other mechanical bits changed as well, and the stock ECU doesn't always adapt to them properly.

 

It's all back to the definition of "BPU"

 

MPG would be a bit better, since it wouldn't be running filthy rich after 4Krpm, like the stock ECU does (this was one of the first things I wanted to address on mine)

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Gains of 40bhp just from leaning the transition?

No way Hose.

I've done back to back dyno runs with stock vs trimmed fuelling at 1 bar and even then the difference was nowhere near 40bhp.

(I was hoping that it would be, but it wasn't, lol...)

 

Not sure how different the various JSpec maps are though.

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Gains can be made by advancing the ignition untill the torque curve plateau's as well as leaning the AFR's out and gaining power there. I wouldn't like to put a figure on it though. I should imagine dimitri knows a fair few little gems to eek out that last little bit though.

 

Is it worth it? if you're going bigger and better in the future, yes. If you're not going much futher then a piggyback of somekind would do the job a lot more efficiently in terms of cost and hassle.

 

MPG. Yeah right. All that happens, (and I can guarantee this will happen with you) is that you lean the mixture out a say 1 bar, and it makes a bit more power. So all you do is raise the boost up to 1.2 bar, which needs to use that extra little bit of fuel you would have just "saved". Yeah if you stuck at 1 bar it would be giving better mpg. But you'll be used to the economy of your car by now, so you'll just "say sod it, I'll just have a faster car and live with the same mpg as I got beforehand."

 

Best of luck which ever way you go mate,

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Gains can be made by advancing the ignition untill the torque curve plateau's as well as leaning the AFR's out and gaining power there.

actually the stock ECU does an excellent job at this, automatically and continously.

I think that's one of the reasons for the reputation of this engine as 'robust' under stress.

I wouldn't like to put a figure on it though.

I can, because I've chased it and measured it.

I'm still looking for the 'fundamental flaw', remember ;)

 

... you lean the mixture out a say 1 bar, and it makes a bit more power. So all you do is raise the boost up to 1.2 bar, which needs to use that extra little bit of fuel you would have just "saved".

I was thinking along similar lines, but in reality it doesn't behave like this exactly. Some of the fuel 'trim' has to be done at revs/load that don't get much affected by the increased 'max boost' settings.

So funnily enough the fuel trim 'map' I had for 1 bar boost is not dramatically different to that at 1.1 or even 1.3bar.

 

...which appears to be contrary to 'common sense' as at high boost settings you'd expect to be using up all the fuelling 'reserves', so the trim ought to be unnecessary. (but it isn't!)

 

[ Mind you, I'm talking about UKSpec setup, I bet the JSpec hits limits way earlier ]

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John, you're just not winding the boost up enough then mate. :p ?

very funny:clap: :p

I've even run it without a wastegate signal to check on the airflow trend (not worth it, even with my setup)

Out of interest, what did you use to lean out the AFR's? ?

AFCII

What AFR did you run at?

various, from 11:1 to 14:1

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...they seem a lot more keen to try things over there than just reading about them.

yeah, lately I'm getting lots of PMs and emails from SF people about my version of the EBV mod that I recently posted there.

 

They do appear to be a lot more experimental --- plus their spec is much closer to UKSpec, compared to the majority of JSpecs over here.

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Some tuners say, that once you get near the top end of BPU parts installed, like cams - a programmable ECU will start to show bigger improvements/benefits for each mod added as you will be able to maximize it's use, with the re-mapping of the ECU.

 

This not only gives you VFM for each mod added but, the full performance of it too.

 

(Yes, there is the cost of the re-map each time)

 

As with everything, it depends on what your goals are and the ECU upgrade is obviously getting ready for the next step – Going Single .

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..Are you saying that you're using more or less the same amount of fuel at 1 bar as you are at 1.3 bar yet with the same AFR's?

At some rev points the AFRs stay the same, at others they change. If you run 1 bar vs 1.3bar at full power revs obviously you need to trim less fuel at 1.3 to sustain the same AFR.

But you still need to trim fuel from some parts of the curve overall, this is not a supercharged engine where more air is forced in the cylinders under all (full throttle) conditions.

 

My point was that even running high boost one may still find that the stock fuelling needs optimising.

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