I may be onto something that may save us UK peeps a bit of money... it involves a small amount of effort, but if I am correct, you may well be able to get a map sensor chip for circa £3 sterling... ok... it won't be new at that price, but it may be an option for those struggling to get / afford the MPX4250AP chip...
I have some cutting up and testing to do over the weekend and into the early part of next week, but I should know more by Wednesday 17th.
MAP sensors
Moderators: JeffC, rdoherty, stieg, brentp
-
capri_turbo
- Posts: 122
- Joined: Tue Jan 10, 2006 8:17 pm
- Location: North Yorkshire, UK
More info please! Sounds
More info please! Sounds like you'd be repurposing an automotive map sensor? Does it have the same pressure/voltage curve of the MPX4250AP?
Brent
Brent
-
capri_turbo
- Posts: 122
- Joined: Tue Jan 10, 2006 8:17 pm
- Location: North Yorkshire, UK
Brent, here's what I have found so far
When I got all my EDIS stuff from the local breakers yard, I got it all from a 1990 Fiesta XR2. I just grabbed the whole lot, which included the factory fitted MAP sensor. I decided to open up this map sensor, and inside there is a PCNB fitted with a PIC and a similar map sensor chip. The only problem is that this chip doesn't have the pipe built into it... it is simply sealed into an enclosure within the map sensor body which has the connection to the manifold...
This is where it will get a bit difficult, as the chip i.d. is on the side that I cannot get to, and to get to it will involve ruining the chamber that the chip is sitting in, which will destroy the unit.
What I will do is carefully cut the case to get the chip and it's cavity free from the rest of the unit and then run some tests on it at work. It is definately a Motorola chip though.
I'll also sort some photos of it over this weekend too.
This is where it will get a bit difficult, as the chip i.d. is on the side that I cannot get to, and to get to it will involve ruining the chamber that the chip is sitting in, which will destroy the unit.
What I will do is carefully cut the case to get the chip and it's cavity free from the rest of the unit and then run some tests on it at work. It is definately a Motorola chip though.
I'll also sort some photos of it over this weekend too.
Will the seperate unit type
Will the seperate unit type as used in some fiestas work? , how important is it that the curve matches as long as the output range is 0 to 5v across the required Map range?. If the unit is mapped to the car the actual response curve of the sensor would not be critical within reasonable limits.
Paul.
Paul.
-
capri_turbo
- Posts: 122
- Joined: Tue Jan 10, 2006 8:17 pm
- Location: North Yorkshire, UK
Bad news I'm afraid...
The sensor used withing the Ford Map sensor (from a normally aspirated Fiesta XR2) is "MPX4101A" and from looking at the data sheet, it won't be suitable...
It was worth a try though.
It was worth a try though.
Well...it's not completely
Well...it's not completely unsuitable, provided that...
1) You have a normally aspirated engine - since it is only rated up to 105kPa
2) It is mounted in an enclosed box that is connected to 'manifold pressure' - since it does not have a direct vacumm connection as in the normal MJLJ MAP sensor
3) You can get the wiring from the sensor, throught its box and into the MJLJ
4) The Lookup Table in the MJLJ firmware is modified to take account of item 1) (..or you do an implicit conversion in your head when you see the MAP bin values in the Configurator vs. the actual MAP values they represent)
1) You have a normally aspirated engine - since it is only rated up to 105kPa
2) It is mounted in an enclosed box that is connected to 'manifold pressure' - since it does not have a direct vacumm connection as in the normal MJLJ MAP sensor
3) You can get the wiring from the sensor, throught its box and into the MJLJ
4) The Lookup Table in the MJLJ firmware is modified to take account of item 1) (..or you do an implicit conversion in your head when you see the MAP bin values in the Configurator vs. the actual MAP values they represent)
-
capri_turbo
- Posts: 122
- Joined: Tue Jan 10, 2006 8:17 pm
- Location: North Yorkshire, UK
It won't work properly unless as you say
the tables in the firmware are altered. I don't actually need to use it anyway, as I have the MPX4250AP fitted already to my MJLJ, I was merely trying it out to see if there was a cheap way of obtaining this part for future reference. As I got the part for nothing, I havn't lost anything, but have gained some knowlege. I'll try and get hold of a Fiesta RS Turbo one next and have a look inside that one as that should be a 2 bar one.
Martin's right, it could
Martin's right, it could still be usable for a normally aspirated engine. You would need to modify the lookup table to convert the appropriate KPa values, but once you do that, you're set.
Makes me think the firmware should expose this table and make it writable....
Brent
Makes me think the firmware should expose this table and make it writable....
Brent
-
capri_turbo
- Posts: 122
- Joined: Tue Jan 10, 2006 8:17 pm
- Location: North Yorkshire, UK
So this info may be of some use afterall
I'll do some photographs of the unit, but unfortunately it is now dimantled, but I can easily reassemble it (sort of) to explain how to get the unit out intact.
I'll get onto it this week.
the idea of being able to configure the map sensor in the firmware sounds good.
If only we had a good supplier of the MPX4250AP here in the uk... Looking at Freescales website yesterday I notice they are sub $10... which equates to about £6... Over here the sensors retail for more like £19, which is closer to $30... Rip off Britain at it's worst.
I'll get onto it this week.
the idea of being able to configure the map sensor in the firmware sounds good.
If only we had a good supplier of the MPX4250AP here in the uk... Looking at Freescales website yesterday I notice they are sub $10... which equates to about £6... Over here the sensors retail for more like £19, which is closer to $30... Rip off Britain at it's worst.