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Info: ECU - Mapping
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Old 14 Jul 2006, 10:42 AM   #1 (permalink)
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Info: ECU - Mapping

ECU - Mapping

An Engine Control Unit (ECU), also known as Engine Management System (EMS) is an electronic device, fundamentally a computer, that is part of an internal combustion engine, which reads several sensors in the engine and uses the information to control the ignition systems of the engine. This approach allows an engine's operation to be controlled in great detail, allowing greater fuel efficiency, better power and responsiveness, and much lower pollution levels than earlier generations of engines. Because the ECU is dealing with actual measured engine performance from millisecond to millisecond, it can compensate for many variables that traditional systems cannot, such as ambient temperature, humidity, altitude (air density), fuel octane rating, as well as the demands made on it by the driver. In addition, to a large degree it is able to compensate for the gradual wearing of the engine as it ages, which in practice allows it to extend engine life to two or three times that of engines of twenty years ago.

Although you want the settings to be adjusted for best fit, it doesn't always work correctly and can sometimes have the reverse affect, a bad batch of fuel can cause the ecu to create strange settings that can be detramental to the engine once good fuel is put back in. (by bad fuel i mean fuel that has got to high water content or been contaminated on some other way)

Mapping

One of the most commonly done things, is whats called a remap. No two engines are the same, small differences in tolerance can affect not only the way an engine runs but also the performance and econemy.

Due to the nature of engine, and the slight variations in tollerance, the generic maps have to be set so if the engine runs slightly lean (more air than fuel in the burnign mixture) or slightly rich (more fuel than air) causing the engine to not run correctly or actually damage itself, therfore they are set to a certain range rather than a specific level.

By remapping the ecu, the anomilys and modifications done to the engine can be used to full potential rather than a generic medium.

For example,

My car is a MY00 UK turbo impreza.

The cars was put on a rolling road diagnostic machine which reads power out puts and sensor readings from the ecu (if connected correctly) before it was mapped the car was running the standard 215bhp/214ftlb of torque.
The catalitic converter was removed from the centre section of the exhaust and then the car was put on a rolling road. The graph below shows the readings given






one of the things highlighted by the run was that there were a few issues within the map of the ecu, hence seeing the slight wave at the top and bottom of the curve. But the run did show that the removal of the cat had increased the power to 223bhp.

to remove the error in the map i decided to have it remapped to custom settings.







once the custom map was done, the car ran 240bhp and 240 ftlb of torque up 25bhp and 25ftlb and alot of the waves at the top and bottom were mapped out, or corrected.

few weeks later i had the final cat removed from the downpipe, and the following graph was produced.






the car had to have the map slightly altered due to the turbo charger spooling up quicker because of the restriction in air flow being caused by the cat had been removed. The car ran 258bhp and 280ftlb, 44bhp and 66ftlb up on power compared to standard.

admitled alot of the extra power came from removing the cat but approx 50% of the additional came straight from tweeking the map to suit my cars engine.

Something to bear in mind about maps is that no two engines are the same, they never have exactly the same sizes of parts, therefore no one map will work the best on two cars.
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Last edited by skylight; 07 Nov 2006 at 09:52 AM.
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Old 19 Sep 2007, 06:51 PM   #2 (permalink)
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most impresive, glad to hear your cars running well, im fitting a few new parts to my 95 uk and ill need a remap too, how much does it cost?
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Old 19 Sep 2007, 07:30 PM   #3 (permalink)
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Ref "they never have exactly the same sizes of parts," tidgy.....................WTF lol

So i guess buying the engine parts from a subaru dealer is a no no then as everyones cars are different pmsl..........................please explain lol

Think what you meant to say is depending on how well a cars been looked after ie driven/serviced or not so well serviced/good oil or not/fuel used

(boils down to general engine condition+supporting mods/ind temps as to results obtained hence varying results from remaps and the need for individual mapping within each engines parameters based on its condition)

did know what ya meant however ya`d explained it better earlier lol where ya`d touched on tolerances etc

Last edited by uk dave; 19 Sep 2007 at 07:51 PM.
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Old 19 Sep 2007, 08:54 PM   #4 (permalink)
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stressed dave it depends what you`re after, some go for Apexi`s although I believe these ar eno longer in production. I also believe scoobyclinic can map earlier classic ecu`s although I may be wrong but what seems to be the more popular choice at the moment is the simtek ecu as myself, JD and Phill type r have gone for. I`m sure there will be somewhere in your area that do these, failing that,m Engine tuner in Plymouth are a good bet Mine cost me £950 for the ecu to be fitted and mapped, including VAT iirc, and an extra £150 as I chose to have switchable antilag too
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Old 20 Sep 2007, 11:23 AM   #5 (permalink)
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Quote:
Originally Posted by uk dave View Post
Ref "they never have exactly the same sizes of parts," tidgy.....................WTF lol

So i guess buying the engine parts from a subaru dealer is a no no then as everyones cars are different pmsl..........................please explain lol

Think what you meant to say is depending on how well a cars been looked after ie driven/serviced or not so well serviced/good oil or not/fuel used

(boils down to general engine condition+supporting mods/ind temps as to results obtained hence varying results from remaps and the need for individual mapping within each engines parameters based on its condition)

did know what ya meant however ya`d explained it better earlier lol where ya`d touched on tolerances etc

you can never manufacture an item to exact sizes unless you measure test etc, so they are made to a tollerance, the slight variations the tollerance causes is the size difference
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Old 13 Aug 2008, 05:55 PM   #6 (permalink)
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Re: Info: ECU - Mapping

hi can u reccomend any thing for my 98 non turbo impreza pm me thanks paul
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Old 13 Aug 2008, 09:00 PM   #7 (permalink)
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Re: Info: ECU - Mapping

will they REMAP cars with high milage??, or is they a limit?
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Old 13 Aug 2008, 11:34 PM   #8 (permalink)
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Re: Info: ECU - Mapping

well andy mapped mine at 102k with no probs what so ever but i suppose it really depends on the state of the engine and whether its been looked after etc.
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Old 14 Aug 2008, 09:27 PM   #9 (permalink)
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Re: Info: ECU - Mapping

awesome, well i had my uk turbo at 62k but now its up to 114k, i just love driving her! ha ha, its well maintained and still has great oil preasure ,so she should be good for the rolling road. but i just wonder how and if they can do anything to my car with remaping? or will they say i gotta spend a wedge of money of injectors and boost sensors first? ?
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Old 14 Aug 2008, 09:38 PM   #10 (permalink)
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Re: Info: ECU - Mapping

mileage isnt really a problem with the scoobs as long as they have been well maintained. Obviously as with any car there is going to be wear and tear.

Cars are designed for 200k or 10 years life span as a rule of thumb so 114k just over midway for an engine thats been looked after.

I think the trick is to gradually increase the power so the materials in the engine get used to the extra stresses etc. dont expect a 200 brake increase to last long if its done over night with that mileage lol
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Old 24 Aug 2008, 01:27 PM   #11 (permalink)
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Re: Info: ECU - Mapping

dude!, after seeing how awesome your car looks with coilovers, i went out and got some too, fitted them yesterday, o my god, it feels like a totally different car, awesome handling!, like its on rails, (thanks for giving me the push) i just need a good fitting front mount intercooler now. can you recomend one?
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Old 24 Aug 2008, 10:11 PM   #12 (permalink)
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Re: Info: ECU - Mapping

I got mine from ebay m8, just over 200 squid for the whole kit. Just be prepared for the whacking and hacking of the front end of your motor.

On your tod it will take 10 hours but if your mates are there, then you can bring that down to 6 assuming you can find all the nuts and bolts that hold the bumper on etc. Just be prepared for cutting a hole in the inner wing next to the air filter, and the massive cut in the bumper where everything goes lol Its amazing how much comes off to accommodate the intercooler.

The bumper is the hardest part, you will need a dremel at least and unless you are a god with a rotary tool its probably best to get some edging strip that matches the colour of the car to cover the edges where you cut.

The effort is worth it though, none of the sitting at lights and wondering where the hell the power is gone due to heat in the engine bay
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