Claw Back Lost Bhp

[andrewl41]

As I understand it the UK ST202 had 173 bhp but then for one reason or another, probably due to cutting back emissions, they made some changes and with them went ~5 bhp leaving 168.

Is it possible to get these horses back, perhaps by putting on an older ECU? If it is will it affect emissions and hence passing of future MOTs?

Thanks,

Andrew

[mikeb]

Not sure if there is anything you can do about it, if it was an ECU thing for emissions purposes. There might be other changes as well as the ECU (connectors, sensors etc). It might be that Toyota found 173 bhp tune was too optimistic for 95 RON petrol, and changed the maps slightly to avoid detonation. Do you know exactly when the change from 173 to 168 bhp came about?

A decat will get you about 5 bhp back though, but you will most probably need a 'friendly' MOT station to pass a test without one.

[andrewl41]

I'm not 100% sure when it happened but I think it may have come along with the 1996 Facelift.

On a similar note, I know the JDM version have slightly more power due to running on ~100 RON Fuel. I think Shell Optimax is about 98 or something. Will the ECU take advantage of this and give a little more power, or even know? I've been religously putting in optimax but it is more expensive so if it's making no difference then perhaps there's no point.

[GT4 BOOSTER]

you will need to reset the ecu to make it any better running optimax, it may remap itself , but i doubt it.

[andrewl41]

you will need to reset the ecu to make it any better running optimax, it may remap itself , but i doubt it.

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I've heard that if you disconnect the Battery for a couple of minutes this will reset the ECU and that it will then map itself it the fuel. I'm not entirely trusting of the sources of this information though. I've also heard that doing this will make the car run like a bag of s**t for quite some time which makes me nervous of trying it. Is it possible to re-map the ECU in a more professional manor to make it like the optimax?

[GT4 BOOSTER]

it wont run like !Removed! at all, maybe for 20 seconds and thats it , taking the efi fuse out 20 seconds- tapping the brake pedal twice is the easiest way.it may work with the bhp but i doubt it will for long .

[andrewl41]

I guess I'd be better off to stop bothering about 2/3 bhp and get a GT4, sadly I couldn't afford to run it.

Thanks fot the info. Any idea what they did to the engine to lose that 5bhp?

[mikeb]

I'm not 100% sure when it happened but I think it may have come along with the 1996 Facelift.

On a similar note, I know the JDM version have slightly more power due to running on ~100 RON Fuel.  I think Shell Optimax is about 98 or something.  Will the ECU take advantage of this and give a little more power, or even know?  I've been religously putting in optimax but it is more expensive so if it's making no difference then perhaps there's no point.

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I just noticed you have a UK car not a JDM imported one. I believe the maps are different for the two (because of the different octane fuel). The UK car is optimised for 95 RON, and I doubt that you will see much improvement from using optimax and resetting the ECU. If you had a jap model, it would definitely be worth using super unleaded and an ECU reset.

AFAIK, the gen 6 knock management is pretty crude. If it detects knock, it retards the ignition until it goes away. Then it will not try advancing it back to the standard map until you reset the ECU. I don't think it will ever go the other way, i.e. advance until it detects knock, then back off a little.

Some of the latest engines have a knock sensor for every cylinder, and they advance and !Removed! timing individually to maximise performance. Pretty sure the 3s-ge never got this treatment (not sure about the beams ones though).

[cookci]

u cud try turning the dissy?

[andrewl41]

AFAIK, the gen 6 knock management is pretty crude. If it detects knock, it retards the ignition until it goes away. Then it will not try advancing it back to the standard map until you reset the ECU. I don't think it will ever go the other way, i.e. advance until it detects knock, then back off a little.

So it is possible that, despite it not increasing the bhp above standard, if the ecu has retarted the engine slightly this would be rectified byt re-setting the ECU so infact it can't hurt to do this just in case. Then keep running it on optimax to ensure the ignition is never retarded again.

[cookci]

Where did you get this information that the ignition is retarded on knock detection and doesnt go back until u reset?

surely we wud all be running round at about 150BHP if this was the case... all you wud have to do is get a tankful of dodgy fuel or run low on fuel and it'd pull the timing well far back.

[andrewl41]

Where did you get this information that the ignition is retarded on knock detection and doesnt go back until u reset?

surely we wud all be running round at about 150BHP if this was the case... all you wud have to do is get a tankful of dodgy fuel or run low on fuel and it'd pull the timing well far back.

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I was thinking this, though if it were the case I guess you would loose that much power as it would only ever happen the once, after which it will always be slightlyy retarded and never knock again. I think I'm going to reset mine in a minute and head to the shops and back, see if it feels any different.

[andrewl41]

it wont run like !Removed! at all, maybe for 20 seconds and thats it , taking the efi fuse out 20 seconds-  tapping the brake pedal twice is the easiest way.it may work with the bhp but i doubt it will for long .

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Which fuse is it I need to take out? Was looking throught the ones here http://toyotaownersclub.com/forums/index.php?showtopic=26524 and wasn't sure. Also do I tap the peddle with the fuse out or once it's replaced? What does this bit achieve any way?

Thanks

[cookci]

remove the negative power lead from Battery for a few mins...

thats all u have to do

[andrewl41]

remove the negative power lead from battery for a few mins...

thats all u have to do

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Will that not set the alarm off? I remember disconecting the lead on an old rover I had and it went nuts.

[cookci]

mine has a DIY alarm but ive never heard of anyone having any trouble doing it and people have been recommending it for ages

[dymchurchpaseo]

...........

[andrewl41]

How long did it take for the poor tick over to improve, 20 Mins, 2 hours, 2 days? Just so I know what to expect.

[dymchurchpaseo]

...........

[mikeb]

Will that not set the alarm off? I remember disconecting the lead on an old rover I had and it went nuts.

I disconnected my Battery the other day when playing with my amps, (97 GT, standard alarm), it made a beeping noise for a bit so i put my fingers in my ears, having been deafened before on other cars. Only to find myself standing there looking stupid. Incidentally the keys were in the car. So no problems there.

Connected it all up after about 3/4 hour, all good. But upon driving the car i found that it stalled at junctions- the revs wouldn't catch at idle speed- they'd just drop and i'd stall it time and time again. :censor:

The fuel economy improved a phenomonal amount though.

Fortunately the stalling has now stopped, and yet i'm still getting better fuel consumption. No noticeable difference in performance.

Does ECU retardation have an effect on economy as well?

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If your alarm is deactivated when you remove the Battery, most do not go off. If you leave the Battery disconnected for a very long time (months), then the memory backup battery in some alarms can go flat, and they loose their ID/keyfob ID. But a couple of hours should be fine.

It could be that the part of the 'learning' program in the ECU has to recalibrate the reading from the lambda sensor. Until it does that it could cause idle problems. Just guessing though.

Retarding the ignition reduces both power output and fuel economy.

[andrewl41]

All good then, I'll do this before heading home from work tonight and by the time I get home my baby should be back to full strength, assuming it's not there already.

[sotal]

With me doing crap journeys all the time, Is it worth me reseting the ECU so that it can learn the normal journey I have??

I also read somewhere how modern cars don't like to be reset and that when you take a car in for work to be done on it, the connect a device up to the leads before the disconnect the Battery which provides a lower current feed - so the car doesn't loose it's settings but also can't give the mechanic an electric shock and can't start the car.

(btw that was a Ford Focus I was reading about - just guessing that it would apply to any car with an ECU??????????)