Theory - MAF and MAP functions on MAF equipped car
14-01-2005, 10:22 AM
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Theory - MAF and MAP functions on MAF equipped car
I started to wonder on one think - what are the uses for both those sensors for th ECU.
In MAP only car the fuel and ignition BASIC maps are tables of values for pressure * rpm function. On MAF equipped athmospheric car it would be flow * rpm, what about the car that has both - like EEC VI Escos, Impreza? Is it switchig from one sensor to another, or compering both, or what? My Escos when MAF disconnnected idles very badly but apart from that drives (I know because once after turbo change I drove for a test drive without it connected - sombody missed it) although performance is very poor (very lean perhaps)? Impreza does something similar although it will idle even worse withoout MAF and won't go over 3 to 4k rpm. So how does it work?
In MAP only car the fuel and ignition BASIC maps are tables of values for pressure * rpm function. On MAF equipped athmospheric car it would be flow * rpm, what about the car that has both - like EEC VI Escos, Impreza? Is it switchig from one sensor to another, or compering both, or what? My Escos when MAF disconnnected idles very badly but apart from that drives (I know because once after turbo change I drove for a test drive without it connected - sombody missed it) although performance is very poor (very lean perhaps)? Impreza does something similar although it will idle even worse withoout MAF and won't go over 3 to 4k rpm. So how does it work?
14-01-2005, 10:31 AM
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Originally Posted by Stu @ M Developments
On your system:
MAF is used for density and speed calculations based on mass airflow and temperature.
MAP is used for boost pressure calculations, targets and limits.
MAF is used for density and speed calculations based on mass airflow and temperature.
MAP is used for boost pressure calculations, targets and limits.
So Map is needed only for boost control not for fueling/ignition. Am I right?
14-01-2005, 10:44 AM
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Originally Posted by Stu @ M Developments
No,
The system is all integrated and requires all input to correctly function.
The system is all integrated and requires all input to correctly function.
I didn't say it like - you could remove the MAP altougether or something, I just wondered what are the basic principles - you know idea of it's internal workings for intellectually impaired
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14-01-2005, 10:58 AM
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Originally Posted by Stu @ M Developments
Well,
Boost calculations naturally affect fuelling and spark timing, i just took that as a given fact you would know. Sorry.
Boost calculations naturally affect fuelling and spark timing, i just took that as a given fact you would know. Sorry.
There are some things I still do not understand but this is very technical and takes time. To know how much air we have we have in cylinder to know flow + rpm or pressure + temperature, at least that is what I thought. This would mean that we could calculate boost without knowing pressure. If there is such mass of air at such rpm and such ambient temperature then it must be at such and such pressure. That's what I would think if it was physics task but apparently engine managment does it in more complicated way - probably because of same factors I can't think at the moment or just safety and accuracy.
14-01-2005, 12:17 PM
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yes, i'm curious as to what you think is a map sensor (and ive got a sneaking suspicion you're talking about the one that runs off the exhaust)
14-01-2005, 04:45 PM
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sorry johnny, cant get on PF as much as i used to at the moment coz i just started a new job n dont wanna take the piss too much.
i'm still waiting for you to show me your map sensor, as i'm pretty confident that you dont have one. i used to think the 24v was map based, but i was wrong. mine certainly doesnt run one, and i can't find any reference to a map sensor in any of the wiring diagrams and documentation i've got (which is a fair old ammount!) on the 24v
i'm still waiting for you to show me your map sensor, as i'm pretty confident that you dont have one. i used to think the 24v was map based, but i was wrong. mine certainly doesnt run one, and i can't find any reference to a map sensor in any of the wiring diagrams and documentation i've got (which is a fair old ammount!) on the 24v
16-01-2005, 11:52 AM
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Originally Posted by Jim Galbally
no, sorry... got every other combination of sierra/escort v6/cosworth etc. etc. but nothing for the small turbo esccos 
16-01-2005, 01:09 PM
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actually, i have got one! 
but its on autodata, and i dunno how to import it as a pic n also how to get all the component names
might be easir to get hoold of a cpy of autodata 2004 CD2 yourself mate
but its on autodata, and i dunno how to import it as a pic n also how to get all the component names
might be easir to get hoold of a cpy of autodata 2004 CD2 yourself mate
16-01-2005, 01:26 PM
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Autodata 2004CD2 - will check.
Dunno if it will be anything like reality because I remember trying to diagose ABS problems using autodata and everything was wrong, there wasn't rear sensors on diagram and ECu was supposed to be lcated inside the car not in the boot as it is.
Dunno if it will be anything like reality because I remember trying to diagose ABS problems using autodata and everything was wrong, there wasn't rear sensors on diagram and ECu was supposed to be lcated inside the car not in the boot as it is.
16-01-2005, 02:31 PM
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sorry i made a cockup there...i was looking at the RS2000 
it said "2.0 RS 4x4" and it didnt twig till stu pointed it out
nothing on the cossie cept for ABS diagrams
it said "2.0 RS 4x4" and it didnt twig till stu pointed it out
nothing on the cossie cept for ABS diagrams
23-01-2005, 12:01 PM
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ok, i found out what it does (well, i got told wat it does... lol cheers gearboxman )
it is indeed some form of basic map sensor (ie it read manifold pressure to calculate load). All this sensor is actually used for however, is the autobox stuff... it's used so the box can calculate when to shift into 4th, if the load is low, itll shift early, if the load is high (ie you're nailing it) it'll shift later. Therefore this sensor has absolutely no relevance to us whatsoever and we may aswell simply not bother connecting it up (it shouldnt drop into LOS because of this sensor)
dunno what the sensor's called tho... Electronic Vacuum Regulator sounds about right, but its got the wrong number of pins :
)it is indeed some form of basic map sensor (ie it read manifold pressure to calculate load). All this sensor is actually used for however, is the autobox stuff... it's used so the box can calculate when to shift into 4th, if the load is low, itll shift early, if the load is high (ie you're nailing it) it'll shift later. Therefore this sensor has absolutely no relevance to us whatsoever and we may aswell simply not bother connecting it up (it shouldnt drop into LOS because of this sensor)
dunno what the sensor's called tho... Electronic Vacuum Regulator sounds about right, but its got the wrong number of pins :
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