Since i've had my JECS ECU remapped (preMY97) i've tried to get my head around what each parameter has an effect on. I've seen some very nice 3D graphs of the ingnition/fuel maps etc. but most of it has just gone way over my head. I would like to learn a little bit more about the subject and as such does anybody know any good technical websites that can help me understand this very complicated subject. Questions that i have at the moment are really simply stuff but i would like to get more into it in the future.

Cheers,

Tony.
P.s im supposed to be a Mechanical Engineer so although i want it fairly simple i don't need big bright pictures and 4 word sentences..... i should be fairly technically literate (then again i mught not be 'cos im damm sure i can't even spell! ).



[Edited by Tone Loc - 10/25/2002 8:36:52 AM]

 

I'd like a few pointers along these lines as well. (Again, I'm supposed to be an engineer...)

 

I don't think you want a website on mapping (I don't think there is one anyway!), I think that probably you need a read of one of the books specifically aimed at the modern turbo-charged engine which should give you a good idea of what all the parameters mean. Far more handy, even if you are a mechanical engineer!
A good read for a 'starter' book is the Corky Bell one.. umm, I'm sure I can find a reference somewhere... ah: "Maximum Boost: Designing, Testing and Installing Turbocharger Systems", ISBN: 0837601606, and info here.

It doesn't specifically look at mapping, by the way.
Well, it might help

 

Cheers,

It seems to cover a vast amount in 256 pages.... seems to offer an introduction which is really all im after. Also linked from Amazon is a book called 'Engine Management' by Dave Walker..... might be worth a look too.

Tony.

 

I think you'll find you need more than an introduction!
Mapping & all the understanding that's needed for it is quite complex

 

You've got to start somewhere tho haven't you. It's no good jumping straight in without knowledge of the basics. It's true about everything really not just engine mapping. That's just common sense.... i don't plan on buying the book then remapping the car the next day . Everything is a learning curve and it will be very steap at first but i intend to SLOWLY build up my knowledge on the subject .

Cheers,

Tony.

 

Nom, you say it is complicated, but the basic principals are mind numbingly simple! ( you just know too much! lol )

It's only all the practical considerations (boost surge, overboost, hitting boost targets, charge temperature, solenoid duty cycle, etc etc) that start making it very very (very) complicated!

Tone, are you looking for "ECU's for dummies" or an open university course?

 

Watching this thread with interest, wouldn't mind learning a bit myself !

Automotive electronics/computing would be my area of major interest...

[Edited by BoxerFlat4 - 10/25/2002 3:51:52 PM]

 

Steve... to begin with ECU mapping for dummies .

At the moment im after basic answers to easy questions. Such as.... a few boost duty cycles i've seen are quite different for the same level of boost why? What effect the ignition timing has? If the boost level is increased from 16.5 psi to say 18.5 psi what should be done to the ignition, boost duty, fuel etc? If it's knocking is it best to add fuel, retard ignition, a bit of both etc. I do pretty much know the answers to these (so im not completely stooooopid ) but i think that im really missing the very basic principals to fully understand why?

I've found that with most things the basics behind the theory aren't that complicated, it's when you just dive in without proper research that things start getting confusing.

Cheers,

Tony.

 

Tony YHM. Let me know what you think.

 

come on jb, don't keep the rest of us wondering ?! Spill the beans, how do you clever clogs manage it, eh ?

 

Tony your email account rejected the email because of the >1MB attachment. Boxer YHM.

 

Another one here two please John

Ta,

Matt

 

Cheers JB - many thanks.

 

If there's some interesting docs going round, can I join in please?

(mailbox shouldn't reject a 1M attachment...)

 

Matt take it and pass it on to the next bloke pls

 

JB...if there is some enlightenment for dullards like me then please count me in!



(note: I never professed to actually know what I was talking about!) lol

 

John, YHM

Tony.

 

Corky bells book is OK, tho has no relevance really to mapping engines.
Dave Walker may be good to read in CCC. But his book on Engine management is very basic, and actually covers very little relating to engine management, other than trying to advertise his Emerald system, which is actually quite basic.

 

I found the same with Dave's book, Steve. A bit overrated. Not found any decent books with any meat in them dedicated to turbocharged engine mapping.

 

can i have a read too john

 

I'd also like to know other people methods too please......

 

Now you tell me!!!

Dougie

 

Could someone forward said document onto me aswell, thanks e-mail as per profile.

 

Interesting stuff John.... guess i need to learn a bit more about hexidecimal if im goin to do a bit of JECS remaping. I've so far had a play with maps in excel that have been converted from hexidecimal to decimal (thanks to Scott T for these ).

John... quick question.... what sort of ignition adavnce have you been able to run on your/other peoples cars (around the 16.5psi boost mark)? It appears that at high load/high revs ('bout 47deg advance, 9 and a bit AFR.... not sure of the numbers tho so i'll check on Monday) i get a lot of activity on the knocklink???? What do you think?

Cheers,

Tony.

 

scott, john, tony... can you forward me it?? please??

David

 

Sorry no email access at present. Someone please forward it to anyone that wants it, but don't put it on the web at present please. It is just a very basic article about ECUs with a few diagrams, nothing too exciting. It's not really going to tell you how to map.

47 at the top on full load sounds high.

From memory the standard Subaru maps go up to 2E at high revs on minimum load - this is about 46 + static (often about 10) BTDC. In the midrange on full load on the map (which is might not reach so maybe more advanced) it is 0D which is 13 + static, rising to 26+10 at high revs, but it would not usually hit this area so probably run about 5 degrees more than this.

I advance the timing in the spool up area, and stretch load headings so that the timing is a bit more agressive. I usually make some new load areas at the same time for full load, and the timing is retarded to safely run a bit more boost.

On a heavily modified car with a big turbo you really need to rethink these timing curves. Would be clearly inappropriate to use 36 degrees BTDC at high revs when you are running almost double standard boost in this area, but only nutters do that.

FWIW my latest timing curve is 20 midrange rising to 25 at the top. Quite retarded but I was running 1.4 bar dropping to 1.3 bar. Can't play at present as the TD04L is back on for "technical reasons" whilst the MD304 gets looked at. Ahemmm. Feels like there is no torque at all, but not very free revving either It is possible the MD304 could have oversped due to a restrictive inlet pipe, creating a much higher pressure ratio across the compressor wheel than the manifold pressure. Need to see after it has been inspected.

Interestingly the FMIC did not give me any more - probably because I turned the boost up to compensate.

Rules of thumb are 1 degree retard per extra degree of boost and 1 degree retard per 5 deg C increase in charge temp. This is only a very rough guide, and you have to apply both. So if you add 5 PSI (and so maybe 10 degrees C depending on turbo and IC eff) you might need to take off 7 or more degrees before you go and drive it cautiously listening for det.

My suggestion is not to chase the ultimate timing as you will only be right on the edge of det - find the point where it is consistently free of det and THEN pull it back for a good safety margin. Don't lean it out too much - 0.88 - 0.89 is sensible IMHO, especially with a TMIC. I often run higher. Subaru run higher still.

Think also about what zones will be hit if the car overboosts - particularly for track use. The last thing you want is a dirty great boost spike when you have fuel starvation out of a hairpin with a heatsoaked intercooler on a small turbo running big boost on a hot day, hitting an area of the map it has never seen before.


[Edited by john banks - 10/26/2002 9:15:00 AM]

 

David, it's on it's way!
The version that i have sent isn't the full one. John had to mess around with it to get it past the Hotmail 1MB limit (attachment was too big)!! I will send you the full version when i get to work on Monday.

Tony.

 

I've sent David the full version.

 

John.... just had a read over your last reply and i think that i'm getting a bit more of an idea but little bits keep poping up that add to my confusion . For example why is the timing say 26 + static.... whats the static bit (or am i being completely stooopid not knowing this)? Tips like how many degrees to knock off for an increase in boost is really useful.... excellent stuff .

Out off interest if one of your customers went up to say 550cc injectors how would you compensate, or does the Ecutek software have a section where the type of injector is listed. I ask because i know a few people (Scott, David, Paul etc) have identified a bit on the Pre97 ecu that lists the injector type but don't really know what this number relates too???

David... what did you and Paul do on your map to allow for the 550cc injectors. Is she purring yet?

Cheers,

Tony.