by bimmer » Mon 08. Jun 2009 23:27
Hér er smá ritgerð frá Hr. X um Alpha-N (er ekkert að leiðrétta stafsetningarvillur frá honum):
I just have some spare time in an airport so i will just fill you in what Alpha-N actualy is..
I have been working with race cars all my life and in racing we like to keep thinges as simple as possible and let as few sensors as possible be involved in correcting the base map made for the car!
By doing it that way we have less chance of sensor errors taking us out of the race.. this doesnt mean that we dont have a **** load of sensors fitted to the engine!! We have almost everything you can think of but only fitted for monitoring and logging..
Alpha is the term of the first used factor to calculate the engine load.. and that ofcause is the throttle angle! the "N" is the engineering term of revs. so alpha-n is the throttle angle vs. rpm in a 3d load map that will replace the messured values from the missing mass air flow sensor(MAF)..
The Mss52 ECU have like alot of other ECUs a replacement tabel if the MAF goes bad! the problem is just, the acctual diagnostic function for entering that tabel is really bad so the car normaly runs like **** when they dont work... that doesnt mean if you just disconnect them you would have a nice running car.. because the manufactores like BMW sets the replacement tabel for the MAF low or high so the car either runs rich or lean! but it will still allow the customer to get to the workshop!...
The main reason for the MAF is the emission aproval test.. this test is very hard to pass for the manufactors, and with more polution the more tax pr. produced car.. thats why you see some manufactors use the same engine in models with different preformance!! they save money due to the lower emissions...
The MAF function for the emissions is to give the ECU a precise information of how much air thats going thrugh the engine! so it can make sure the emissons values are 100% at all times no mather engine condition!!
THIS doesnt mean that your car will make the birds fall of the trees when you pass in your MAF less M5, because... during the emission test the engineers block 85% of the airfilter and change 50% of the engine oil to some black thick ****, then they drive around to see if everyting is still ok!
The rule is if 2 customers buy a car the same time and A makes all the services the next 60000miles and B only change the oil 2 times in 60000miles... the emission rate from the cars must be the same!! and you cant compensate for that unless you use a airmass meter to help you out!! or a mapsensor like the CSL so the ecu knows the state of the engine... so if you do run MAF less keep your services..
When you fit a SC to a M5 the poor quality of the MAF sensors can do alot of mess of the base mapping of the car.. and then the companys who makes the SC kits will have big problems with their kits because none of the cars run like the car they used for developing the software for the kit.. thats why the easy sollution is the MAF delete!! so whats done is just disconnecting the airmass sensor take care of the error code shown by the ECU for no connection to the MAF and then you start to tune the replacement tabel and the fuel maps...
alot of tuners dont change the replacement map for the MAF and it will work ok too with the from BMW preset values, and the main reason for this is the car isnt fitted with wideband sensors!((thats another story) your E39 M5 can acctualy be converted to wideband sensor i have done it on 3 engines fitted in e36 and e46 chassis used for racing! the cars are N/A and MAF less.. i make them run close loop(full lambda control) at all times and it works very nice.. so it can be done )
anyway i need to catch my plane... im sorry for all the spell errors and all the missing...,.,.,.,..,..,.,. i just but a few so you put them in your self..
I hope i have made Alpha N and why abit more clear.. if not!! sorry...
Þórður
'99 M5 SC // '89 M3 S85 // '04 Patrol GR

Alpina wrote:S85 er vondur mótor þó að hann sé kraftmikill...