I have heard many times that once you have an aftermarket ecu you have to get a remap after every subsequent mod. Why is this?

I can think of a few possible reasons but not sure which is correct:

1. It's not essential but to get best power from the setup it will need a tweak

2. Aftermarket ECUs cannot "learn" like the stock unit. The only reason I can come up with for this is the huge amount of time/work it would take to setup the map for it.

3. The map on the aftermarket ECU is specific to your car, as opposed to a bit of a fudge like the stock map. It is closer to the limits of the engine (people often talk about increased MPG so i guess the risk of running lean is greater after a change) so it is more sensetive to any changes in setup.

So am I anywhere near the answer or way off as usual?

TIA

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JDM ST205 (286bhp and 281lb/ft)
JDM ST202 (Finally sold )
1982 Pontiac Trans Am 5.7L V8 (See my website)

I think 3 is the major point. an aftermarket ems is going to be tuned closer to the bleeding edge. otherwise you may as well not fit it. so you have decreased safety margins

you can get learning ecus. in fact there are some which are considerably better than the stock denso.

the standard ecu isn't really that smart. it will tweak cruising maps based on feedback from the o2 sensor but still goes open loop (o2 feedback is ignored) when exercising the right foot.
Some ems systems (the hydra nemesis for eg) allow you to set a target afr across the rev/load range. the ems then uses a proper wideband sensor to accurately map to this map. so this is much better than stock

timing wise neither the stock nor any ems system I know will map for you. the denso unit will retard timing based on knock feedback. it will never (that I know of) advance the timing. again there are ems systems out there (again the hydra unit is an example) which can switch to knock retard maps based on knock sensor feedback

Cheers Steve. I wasn't expecting such a swift response at this time of night

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JDM ST205 (286bhp and 281lb/ft)
JDM ST202 (Finally sold )
1982 Pontiac Trans Am 5.7L V8 (See my website)

guess i'm not the only one who can't sleep lol

Maybe , start learning to use an aftermarket ecu now.

mapping is an art form, takes many years before coming of age..

the likes of Adrian make it look easy, thou I have never met the guy, but hanging around with other chaps who have yrs experience make it look so very easy.


I am a newbie, but have understanding, this has helped , its very addictive, every trip is a logging trip, every engine has a sweat spot, understanding what & why is a major starting point...

Buy a true open ems, not just one for 3sgte, then it can be used on any vehicle you like, just a plug in connector adaptor..

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Black UK 96 205 shed with heater full on telemetry.

project six million dollar 185, faster, stronger, lighter than before.

Believe it or not I have considered this as a career. There are Unis in america now that do courses in performance engine management and tuning. And, like the japs, they really know their stuff.

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JDM ST205 (286bhp and 281lb/ft)
JDM ST202 (Finally sold )
1982 Pontiac Trans Am 5.7L V8 (See my website)

IMHO and having mapped my car, met someone who has done the course and has been mapping for 10 years my opinion is:-

1) Learning how to map a car is a modestly simple process if you can do maths. virtually all the requirements of a base map can be established from combustion laws. Some of the maths is frightening, some of it need only be used as a ballpark anyway to start off with. This is stage 1

2) In order to start mapping other peoples cars professionally I would not even consider it without a dyno. You can get 90% of the way there on road, the last 10% needs a dyno to ensure a smooth & correct fuelling and timing map are obtained. Ironically I feel that you then need to check the setup on the road as the vehicle is placed under slightly different dynamic conditions on the road. For a good driveable road car a dyno is essential to map out all the oddities and to sort out the emmissions in the cells for fast idle etc testing at MOT time. It may well be possible on the road (I have managed it 95% but boy does it take a LOT of time.

3) A dyno - or a decent one will cost you circa £60K-80K plus dyno cell & accomodation. Bank on a good £120K plus for your first year start up expenditure. Add on a few bits of software, stock etc of ECU's ......

4) A good working knowledge of tuning & fixing problems with clients cars is required, some of the crap that turns up and you are requested to do is just stupid. If you approach it with the attitude that you will only touch perfectly prepared cars you will not have much clientele, repairing, modding & selling teh mods is all part of it too. Trying to figure why thsi car is fuelling eratically will result in you having to test regulators & injectors & fuel pumps etc till you are blue in the face.

I have also thought about this but have decided that the building trade I currently deal with are far easier than the general private punter/chav. If you would like to chat about it let me know m8. I can reccomend a few good books (which will be detailed in teh impending book review article). IMHO your best bet is to start with a power FC that you have a good base map & you need to play with, then move onto complete ems.

Good luck

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JP
GT4DC Treasurer

Grey St185 RC
Silver BMW E46 M3
Multicolour yawn Honda VFR400
Silver Honda Civic Type-R

having watched JP "mapping" his car I would agree with the above. Any fool really can do it lol

It's also something i considered but the vroom, kaboom aspect puts me off lol

The capital needed is an issue obviously. But if I can prove myself initially I hope I could land a job with an established garage. Even if it's as teaboy for feck-all I'm better off than if I had paid for a dyno. There's no point shelling out unless I can establish a decent reputation for myself.

The "vroom, kaboom" aspect is a worry. Especially with someone else's car. But to my mind if you do the job right then that is not a major risk. And doing it right is what floats my boat.

Any books/info on the subject would be gratefully received, though i have a long way to go before I would be ready to embark on a career at it. I want to build and kill a few engines first

P.S. JP, Would A-level maths be enough?

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JDM ST205 (286bhp and 281lb/ft)
JDM ST202 (Finally sold )
1982 Pontiac Trans Am 5.7L V8 (See my website)

What do peeps reckon to this?

Seems like a pretty good place to start (after appropriate reading and research.

_________________
JDM ST205 (286bhp and 281lb/ft)
JDM ST202 (Finally sold )
1982 Pontiac Trans Am 5.7L V8 (See my website)