When ur mapping a turbo car, do u map it differently than u would a 'normal' shopper - when on light loads, crusie off boost etc.

Stu's lambda control map gives awesome economy off boost - but why cant this be achieved using a normal map? Is it a case of resolution?

 

because of correction factors i cant seem to get a stable lambda 1 without using closed loop for light loads

i map them the same try too get good emisions and fuel ecconomy

 

Surely the quality of the map is directly proportional to the amount of time invested in it, which in turn is directly proportional to the amount of money the customer is willing to spend.

Lamba Control will still rule though, Im sure.

(Mine will soon be Lambda Controlled)

 

too bloody right,, ive spent many many hours in my own car,, and its still no 100%

 

Exactly. Also manufacturers spend Months, even Years, perfecting Maps and Tuners are expected to turn out the same quality in less than a day and for a measly sum of money.

 

interesting one this...
on light cruise conditions, providing there's no Cat's to keep happy, engines will in general happily run quite a bit leaner than you are forced to have under lambda control.. Closed loop lambda forces fuelling to Lambda=1 (14.7:1 AFR), normally required to keep the Cat happy. This is a good bit richer than the engine needs, so you would think that it should be feasible to see better off-boost economy from an open-loop map. However I suspect the answer in this case is down to resolution limitations of injector pulsewidth in the map, which in this case is helped by the lambda control strategies....
Stu? Simon? Gareth?...

 

Agree with everthing above !!!

Having access to your own ecu maps is bad news - for me anyway.
Even after 2 years I still tweak it at least once a week - just because I can

 

richm, Modern injectors running modern ecu's can easily control fuel under all conditions.

But again, only will be as good as the mapper and time

 

So, are you suggesting running leaner than Lambda 1.0??

 

do we risk fatigue in things like valves

 

Christian and Beccy, I certainly am not !!! (if that was aimed at me)


I am sure you know but for others....

It is a fact that CATS will work more efficiently (for emmisions purposes) if the mixture is ever so slightly richer than the stoichometric level.

 

im sorry but 400 quid for 6 hours work is not a measly sum of money

most working people dont get that for 80 hours work

i agree that mapping is a precise art but loads of car get mapped in a day and work fine, to get it perfect is a long job but that also means ya need to take all road conditons into consideration, faulty sensors and then understand what the ecu is always seeing and knowing how it will react in all situations

running lean can be ok at times as i ran 2bar of boost in me cossie for 30 miles and it never melted down, but then i wasnt giving it as much stick and it was a fooking cold night ect

 

I run my 16v engine in the 205 without closed loop control, and at light throttle run the engine at around 15.3:1 AFR richening to 12.6:1 at WOT.

With my own cosworth I have run both closed loop fueling for light loads (i.e. up to 4000rpm and less that 4psi) but have now opted for open loop with it carefully mapped to maintain 13.5:1 AFR at light loads. For my car this results in cooler engine running when at cruise seeing a typical port EGT of around 750DegC with 14.7:1 AFR and 650DegC at 13.5:1. For most cars I am happy to opt for the 14.7:1 closed loop cruise but given I run a tubular manifold I try to keep temps down as much as possible.

With regards to cosworth mapping open loop to run at 14.7:1 the issue most commonly found with grey injectors is an issue we call lean stumble and is most commonly found when trying to map on greys. (Smaller injectors don't seem to suffer as much) Closed loop offers greater injector response resolution and gives a more stable control when running at 14.7:1 and removes the greys "stumble" syndrome.

 

welocome back karl and fooking good explanation as i understand it

 

yeah agreed simon but in the specific case of Marelli ECU plus larger than standard injectors? does that make for a incremental injector opening time resolution issue at light load values?

 

 

richm,

The weber marelli ecu's do suffer resolution problems at small opening times like other ecus that only use a
single byte (8 bits, 0 to 255) for the table data.

Also, they have an inbuilt minimum on pulse width that ONLY the "few" know how to modify correctly.

I.E on some maps using large injectors, the table table may be close to ZERO representing the minimum on time.
If this time is big then there will be problems at the low end with control but is required in order to make the maximum value (255) in range.
This is all subject to the multiplier of course.

As and example, fuel is basically calculated like this in ALL ecu's...

PULSE WIDTH= MIN_ON_TIME + (TABLE_VALUE * MULTIPLIER)

For the weber ecu. the multiplier is usually between 32 - 64 micro seconds.

So for a limited value range of 0-255, the courseness of the map becomes critical at lower value.

Having said all this, any map is ONLY as good as the accuracy of the injectors ability to linearly deliver fuel at low end pulse widths.

 

cheers Simon yeah that's essentially what I was getting at

 

Incidentally, regarding the cost thing.

Dont forget that any decent mapper will have a wealth of equipment available to him, such as Wide-Band Lambda Monitor (Ours is a Motec PLM which cost around £1k, we have an Innovate one as a spare).

Then, the car will either be mapped on an Engine Dyno, a Rolling Road or Her Majesty's Highway.

In the first 2 instances, you are talking about upwards of £30k's worth of equipment and in the latter instance you are talking about considerable risk, not only of a potential Speed related accident or Conviction, but the prospect of driving someones less-than-roadworthy car in some cases.

 

christian its still dont take away the fact that the tools for business use are there for business use wether a spanner or a race track

400 quid for 6 hours work is not pokect change in anyway, i think people get to a wage and forget what times used to be like

get 80 quid a hour labour thats alot of money after overheads !!!!!, 400 quid a day labour is 1200 quid takings a day on sales, thats a good day for a small business,

400 quid a day is 2k a week gross profit, 2k a week is 104k a year profit, minus 3k for the mapping tools obv, but then ya got the profit on parts used too to that list and maybe more work out of it, aint bad going is it


infact even 60k a year for a 3k investment is good going in any busiiness i think ya wil;l find

to open a cycle shop reqiures a 20k investment amount and then the profit on the cyclle sales are 20% so to make 20k investment plus 15krent and then rates of 5k

bet ya dont make 104k a year in labour charges though

all this is on paper but it shows that mapping aint small change ya find down the back of a sofa ( unless ya at porkies house )

 

b19bal, you have totally missed the point on the "pathetic sum of money"

400 for 6 hours is a good wage, but 400 quid for a map, which requires in reality hundreds of hours is not enough to do the job right, the only reason people like stu manage it is experience which means they pretty much know roughly where it needs to be to begin with, but if you gave them a totally new engine to map they wouldnt get anywhere near it in that time.

And even with weeks on the their side they would be hard pushed to match the details of a standard map in terms of cold starting etc.

 

chip i do get the point totally but its experience that ya need to make ya quick, its not a shite amount of money though

would you not be offended if ya got told that the 2 weeks wages ya just payed a company for 6hours work was a measly sum of money

thats the point i was making, the whole map from scratch is true but again most tuners have a map adn tweek from there rathre than start a new map, the cold start map does seem to show the difference with a real mapper and a tweeker though , which is not a dig at any tuner ect as i know gary, stu and karl all do cold start mapping and get it sorted proper too

i do take offence when people go on about money when its not a stupid amount, same wioth house prices, another pet hate is people who say there house is worth 200k and they bought it for 30k and they made 170k profit,,,,,,,,,, not really considering there next house has gone up in the same value too


anyway rant over and im sure christian knows what im talking about and hope he knows it wasnt a dig at him but was a comment made on personal thoughts


im off to bed

night all

 

some intresting points come into this through simon karl and rich

SECS,



this screen grab from pectel shows your point nicely

 

Top info

 

This would have been a good continuation of my mapping topic