stu have you ever thought about writing a book? as the way you write tech questions is so easy to follow even for me to read

 

I second that. He has an excellent way of getting the technical information across. through to the basics and to the totally bewildered reader and also enough content to give the more techincal something to ponder.

 

No more questions then guys?

 

i cant think of a good one at the mo

 

OK - here is one - what happens when things go wrong with boost? I know some have got overboost protection in the chip, but is that always there?

Same question re ACT's I guess?

 

erm..

ERST - what stops you from 'livemapping' the ignition on these for example?

also OFAC and OFAB would these be different to map with the different map sensors, and to if the map sensor is limited to 1 bar positive - how would you get around this for running say 18-20psi?

and also t2 to t3 conversions on the frst - would the fueling be totally out for the same boost pressure on these, given that the gains would primarily be down to exhaust housing and pressure efficiencies on the inlet? would there be lots of factors in the map and tables to alter for this simple and common mechanical change?

ok so these arent exactly relating to general mapping, but when put into application it raises a few more queries from me.

 

I was thinking the same thing a couple of days ago lol, blow dave walkers book out of the water in a few days lol, trouble is i'm now craveing more

 

Ok,
One by one....

Depends what application it is, but we will choose Marelli.
The 3bar can have a boost limit up to and including 28.5psi thats still reliable. If you want to run more boost than around 26.5 held, then the boost limit must be removed completely.

The alternative is to fit an alternative method of boost limiter, such as a pressure cutoff switch or a blowoff valve.



ACT's are mapped within most Ecu's and as such nothing can really go wrong with them that the ecu cannot deal with TBH.


Bosch KE's Spark control map is part of a Motorola "processor" and not stored on an "Eprom" as per other designs. Processors cannot be emulated live by conventional emulation methods.


The map sensor doesnt really "limit" anything. If you look at this fuel map:



The left hand column is map sensor output voltage, so obviously, should we change the sensor, the column meaning will change, yet fuelling remain the same.

EG:
Top line is 4.9volts. That on the std OFAB sensor is 1bar positive or 2bar absolute. If we change to a 3bar, that line now equates to 2bar positive or 3bar absolute.

Result = very lean everywhere.
This effect obviously happens to every map that is pressure related.

As for the upper limit of the sensor, once we hit the 4.9volt line, we can run all the boost we like, we will never get anymore fuel, hence when your tuner says: "set it to 28" you dont set it to 34 and presume it will be ok. lol


Generally fuel and spark will both be wrong, with the onus on the fuel. The charnges required arent immense, but they are enough to melt the engine if not dealt with

 

superb!

although raises a slightly different question - once you hit the maximum boost of the map sensor (i.e. 4.9 volts for example) - is it still possible to map the car past this and use the other factors, act, revs, etc to kind of estimate past this - with a known maximum boost limit?

i.e. after 15psi the map sensor just reads 4.9 volts... but you want to run 20psi.. are you saying you could do this but the management wouldnt see any change in boost?
so that to multiply the variables up to get the fuel there, you would have to increase the other values in the table as it wont have an additional mutliplication factor from the map sensor?

how does the frequency based OFAC sensor read in the tables then? would this be similar in that a maximum frequency would be seen?

sorry for all the questions, Im just on the edge of getting how it basically works I think

 

M Brian, once you have gone off the map as it were for mapsensor readings there is not adjustment possible and afaik the extra fuel is supplied by the rising rate of the fuel pressure regulator, could be wrong tho

 

oh right.

id just thought injection duration.. would be like f(act) x f(revs) x f(map) x f(coolant temp) = postion to lookup in injector duration table

and if f(map) was at the maximum then you could perhaps write the chip so that the other functions are increased to compensate or something? or something along those lines?

it wouldnt compensate for the pressure but I would of thought that there would be someway around it?

 

Your missing something here Melv.

And its this:
When the map reaches 4.9Volts it still has rpm factors etc it can read to keep rpm based fuelling correct for rpm. And we can still increase the values and duration it oputs out at that level, but we cannot change the fact it is no longer scalable against pressure.

Put another way:
What it can NOT do is be correct at 2bar of boost(4.9v) and 2.5bar (4.9v) and 3bar of boost (4.9v)

What has to be done is map at perfectly at 3bar of boost, then anything below this will simply be a bit rich

Another good reason why folks shouldnt go the other way either

Tuner: "Set the boost at 34psi"

Customer "So i set it at 26psi for safety"... "Damn, the rings picked up "

The moral? "Always do what your tuner told you to do.." roflol

 

ah right with it now - it just kind of goes blind to boost changes once its reached.

never thought too much of the dangers of running rich - obviously thought of dangers of running lean.

would it be possible to run 20psi on say a t3 FRST, but then drop it back to under 10 for example where it should pick it up within standard boost limits and it be reasonable drive? without major overfueling?

or is that too complex for it - as the RPM based fueling would be set up for running 20 wouldnt it? would it adjust it down if it didnt report 4.9 volts map?

just a quick thanks stu for the info here gives a good guide to me. for what is and isnt possible!

ill step down now - someone else step in and glean info from stu!!

 

I know i keep sayin this, but, elaborate for me

If you mean have a 20psi peak and drop to 10? yes, what makes you think we couldnt?

 

no i didnt mean a peak of 20.

what I meant was inline with what you said here -
IF say on a FRST I want to run 20psi - all out boost held peak whatever makes no odd.
but I want to run two stage boost - for if the missus drives it, or its bad weather, less strain on the engine etc
could I have it set-up to run 20psi AND 10psi.... as 10 psi would be within the boost limit of the map sensor.

as in the example you gave they are both high boost at 26 and 34

 

i think the reason stu gave the 34 psi 26 psi statment was because 34 psi is above the limit of a 3bar map sensor, if the mapping was set using 34 psi then the boost is turned down too the limit of the sensor then it wil still be fueling for 34!

 

yeah im with that part... but if it was easily WITHIN the limits of the map sensor and 2 stage boost was wanted to be ran. would it be viable to do this?

 

yes, as if the ecu was mapped right, it would see there less boost,, less air, so needs less fuel

 

Il draw a picture to illustrate this.......

BRB

 

ill draw pictures to illustrate my questions, may you help a bit!!

 

Ok,
Look at this fuel map.



Ive highlighted the lines im talking about in blue so you cant miss em
Next to the lines, in the map sensor pressure boxes ive written in a boost pressure example.

So:
Top line will be hit at 28psi and above. so at 28psi we are on the top line and at 50psi we are STILL on the top line. Ok?

Good.
Now if we are running 20psi we will be fuelling from the 2nd line.

SO:
If the top line is mapped to fuel perfectly well at 50psi and we drop the boost to 29psi we will be very rich. But if we drop to 22psi we will be fine.

Does that help?

**Disclaimer**
I know damn well the pressure examples are wrong, before any smart arse decides to try and correct me... They are wrong on purpose

 

Good post stu, idiot proof that one

 

I have a saying that disproves that

"Make something idiot proof, and someone will just make a better idiot"

 

yep spot on!!

so with an efi system and map sensor it is possible to have two stage boost then and still be mapped effectively.

I was just a bit confused with your statement of 34psi and 26psi... as id assumed the 26psi would be with the map sensor measuring region and 34psi would be out so didnt under stand the major harm in it?

sorted now though I think!!

 

PMSL, i use that one a lot and also 'i know i'm right you just think you are' is another one i use a bit lol, good for the nova boys that one

 

hey Pjay if youre gonna insult me do it more subtle so I miss it!!!

 

Just saying in general matey, so many people don't get the boost thing but too many are scared to ask for fear of making them selves look silly

 

yeah yeah, ok ok, that was more subtle!!! so youre saying I look silly now are you

another question then....
along the same lines of.. how long is a piece of string.

I make the assumption that to be suitable for every application that an off the shelf chip must be set-up with a high degree of safety.
would you therefore expect a livemapped car to a) be MORE safe as mapped in specific application B) make more power as the safety factor could be evaluated?

if so in terms of a percentage - would you hazard a guess at any gains?
or is it likely to just be in reliabilty, safety and driveability?

 

Now that makes a change....... NOT!!


How longs a piece of string?

Seriously though,
Depends on the application. I dont really advocate the benefits of mapping a perfectly standard car, and if the car is modified, then the maps wrong so live mapping it would gain in all areas.

Or in other words:
"How longs a piece of string?"

 

 

Stu - what do you do when you read an ecu file that is encrpted

 

Nothing Mike. Its encrypted to stop you messin with it, so i dont mess with it.

 

I was expecting a punchline from mikes post?

or I dont know what do you do?

 

All outa questions then guys?

 

so , in relation to the lambda probing in short term fuel trim on any mentioned car , if the manufacturer has decided to use the lambda probe(as they have to) , then the management system can alter its fueling to suit via the voltages recieved from the probe , now lets add more variables , i.e two more lambda probes into the equation, one extra before and then one after the cat, and then create a referance betweeen the values that all the data has to be in a given value for eobd II (cause all these cars weve mapped over the last 5 pages need to be clean these days especially the ones that are compliant for eobd II ) so we then have to look at long term fuel trim , and multiple cylinder adjustment, also , calculated load values of an engine in any given instance , as new systems are clever and so many requirements for 2005 legislation will be in effect , how many of us will be mapping our own cars when the MOT will be pulling us over and checking for operating MIL lamps , interrogating our ecm memory functions then whacking us for a big fine due to non compliancy ??

so with the extra monitoring function of multiple O2s and also the useage of three way catalysts with massive oxygen storage function , how is the performance upgrade going to be a DIY option for the likes of 95% of the PF user

 

Easy Mark.. It Aint

Thank fook


In fact, judging by some DIY stuff ive seen, it fookin isnt now, nor was it 5yrs ago

 

some of the functions i have to deal with on a day to day basis on new manufacturer products would actually amaze people that a) its actually possible to do and b) that you would atually need to use it anyway !!

and these are just for the normal running of an everyday production sportscar (and i use the sportscar and production loosely !) make the weber syetm fitted to teh cossy look like - well lets just say that toasters have more capable electronic control devices

thats not to say it doesnt do its job , cause it does , and very well in some case ,

but more and more cars come with variables that have to be accounted for when the mapping process is carried out , multiple maps are std on a lot of cars ! so to me that makes twice the mapping work for the tuner who decides he can re-map it to be better , the more variables that can affect any points in the map the harder the job gets ,

lets have a bit of a conflab on variable valve timing and mapping

and i do mean VARIABLE not fixed advance/retard systems

discuss yo'll !!

 

fookin hell...

wot a post.

only queestion i have stu, can any ecu be accessed and data pulled out? are manufactoers(sp) adding more security to try to stop people like urself getting in?

have to agree with u writing a book stu, i would deffo buy a copy

 

me ?? nah !! - but - and to quote a famous persons quote " those who can-teach "

or can we have another one - " those who can bullshit - do - lots " - you know who you are !!