3 bar map max reading
08-08-2007, 09:23 PM
#3
thing is if it is supposed to read more than that, and i run 32 psi, the fuelling will be rich enough at the highest point of the map reading on the 3 bar for the peak boost figure, so if its under reading im gonna melt 
it should be 1 bar below atmos, and 2 bar over i guess? so 1 bar is 14.7 psi iirc? so 2 bar is 29.4psi?
it should be 1 bar below atmos, and 2 bar over i guess? so 1 bar is 14.7 psi iirc? so 2 bar is 29.4psi?
08-08-2007, 09:26 PM
#6
BANNED
BANNED
iTrader: (1)
Join Date: Jul 2003
Location: Wiltshire
Posts: 12,483
Likes: 0
Received 0 Likes
on
0 Posts
A 3 bar sensor is only specced to 2 bar boost (28.8 ish psi)
Some sensors read slightly higher than that some dont.
They tend to drift with old age especially if over boosted.
Also, the ecu reference voltage and wiring loom will have some minor
bearing on the reading which is small enough not to worry about.
For the record, any conversion running a 3 bar sensor using more than 2
bar boost and the ecu is guessing the fuelling, it cannot measure it.
Some sensors read slightly higher than that some dont.
They tend to drift with old age especially if over boosted.
Also, the ecu reference voltage and wiring loom will have some minor
bearing on the reading which is small enough not to worry about.
For the record, any conversion running a 3 bar sensor using more than 2
bar boost and the ecu is guessing the fuelling, it cannot measure it.
Trending Topics
08-08-2007, 09:34 PM
#8
BANNED
BANNED
iTrader: (1)
Join Date: Jul 2003
Location: Wiltshire
Posts: 12,483
Likes: 0
Received 0 Likes
on
0 Posts
JTECHSAFF,
Correct.
The ecu will be seeing the maximum reference voltage despite the slight
variation so the accuracy is irrelavant at that point as the ecu will fuel for
32 psi for any boost level from 28 psi and above.
(depending on how yours has been mapped of course)
Correct.
The ecu will be seeing the maximum reference voltage despite the slight
variation so the accuracy is irrelavant at that point as the ecu will fuel for
32 psi for any boost level from 28 psi and above.
(depending on how yours has been mapped of course)
08-08-2007, 09:43 PM
#12
BANNED
BANNED
iTrader: (1)
Join Date: Jul 2003
Location: Wiltshire
Posts: 12,483
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by abdr500
68332
so how come mine wount read abouve even though my boost gauge reads 2.1 bar
so how come mine wount read abouve even though my boost gauge reads 2.1 bar
A 3 bar sensor CANNOT measure more than 2 bar boost.
(exclude the slight variations which can be positive or negative)
A simplified explanation....
The boost is transmitted from the sensor to the ecu as a voltage.
The varying voltage ranges from 0 to 5 volts.
At 2 bar boost, the sensor is ouptuting 5 volts (just under)
It cannot give any more !
Hope that explains it.
08-08-2007, 09:47 PM
#13
and when the ecu sees the 5 volt reading ,it gives the max fuel allowed in the map, this being rich at 2 bar ,but hopefully correct for whatever the max boost is 
id say you would get away with this at 32 or 33 psi, but anymore than that and you would have to fit a 5 bar sensor as the fuelling difference would be to great
id say you would get away with this at 32 or 33 psi, but anymore than that and you would have to fit a 5 bar sensor as the fuelling difference would be to great
09-08-2007, 09:26 AM
#14
PassionFord Post Whore!!
Join Date: Jun 2003
Location: Exeter
Posts: 3,744
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by JTECHSAFF
and when the ecu sees the 5 volt reading ,it gives the max fuel allowed in the map, this being rich at 2 bar ,but hopefully correct for whatever the max boost is
id say you would get away with this at 32 or 33 psi, but anymore than that and you would have to fit a 5 bar sensor as the fuelling difference would be to great
id say you would get away with this at 32 or 33 psi, but anymore than that and you would have to fit a 5 bar sensor as the fuelling difference would be to great
JJ
09-08-2007, 09:41 AM
#15
Testing the future
that is true to some extent, i.e. the analogue to digital conversion can only divide the 5 volt signal into a certain number of 'chunks', so each chunk of the 5v will be a greater pressure when using a 5 bar MAP sensor
but it doesn't mean that you have to use the whole 5 bar scale in your maps, so the interpolation going on there needn't necessarily be much different
nothing wrong with interpolation of the map anyway - it's certainly better than running off the map imo
but it doesn't mean that you have to use the whole 5 bar scale in your maps, so the interpolation going on there needn't necessarily be much different
nothing wrong with interpolation of the map anyway - it's certainly better than running off the map imo
09-08-2007, 11:09 AM
#28
BANNED
BANNED
iTrader: (1)
Join Date: Jul 2003
Location: Wiltshire
Posts: 12,483
Likes: 0
Received 0 Likes
on
0 Posts
Map sensor resolution isnt an issue !!
On weber ecus, the analog to digital converter is 8 bit.
This gives a possible 256 readings of the sensor. I.E. a value between 0 and 255.
So for a 3 bar sensor, this equates to 0.0117 bar (0.1699 psi) per bit.
This isnt that bad actually and can provide pretty accurate fuelling
if mapped correctly in the first place of course.
(figures are not exact but represent what happens)
On weber ecus, the analog to digital converter is 8 bit.
This gives a possible 256 readings of the sensor. I.E. a value between 0 and 255.
So for a 3 bar sensor, this equates to 0.0117 bar (0.1699 psi) per bit.
This isnt that bad actually and can provide pretty accurate fuelling
if mapped correctly in the first place of course.
(figures are not exact but represent what happens)
09-08-2007, 11:18 AM
#32
Originally Posted by 68332
Map sensor resolution isnt an issue !!
On weber ecus, the analog to digital converter is 8 bit.
This gives a possible 256 readings of the sensor. I.E. a value between 0 and 255.
So for a 3 bar sensor, this equates to 0.0117 bar (0.1699 psi) per bit.
This isnt that bad actually and can provide pretty accurate fuelling
if mapped correctly in the first place of course.
(figures are not exact but represent what happens)
On weber ecus, the analog to digital converter is 8 bit.
This gives a possible 256 readings of the sensor. I.E. a value between 0 and 255.
So for a 3 bar sensor, this equates to 0.0117 bar (0.1699 psi) per bit.
This isnt that bad actually and can provide pretty accurate fuelling
if mapped correctly in the first place of course.
(figures are not exact but represent what happens)
09-08-2007, 11:20 AM
#34
Originally Posted by 68332
PMSL @ Tony, you cooooooont
WHEN I invent time travel, I will go back in time and make sure you stick to that diet.
WHEN I invent time travel, I will go back in time and make sure you stick to that diet.
09-08-2007, 11:32 AM
#36
BANNED
BANNED
iTrader: (1)
Join Date: Jul 2003
Location: Wiltshire
Posts: 12,483
Likes: 0
Received 0 Likes
on
0 Posts
Tony,
You can get turbo system stickers/windcreen banners at our local sticker place.
I think people were buying them and the cars didnt perform as they didnt
have your conversions so thats why you arent doing so well these days ...
ROFL
You should have copyrighted your trade mark
You can get turbo system stickers/windcreen banners at our local sticker place.
I think people were buying them and the cars didnt perform as they didnt
have your conversions so thats why you arent doing so well these days ...
ROFL
You should have copyrighted your trade mark
09-08-2007, 11:34 AM
#37
20K+ Super Poster.
Join Date: May 2004
Location: In the boxing ring
Posts: 22,489
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by T S M
Originally Posted by T S M
The problem with the flux capacitor being rare is that it was a product form simon at secs.I ordered mine in 1973 and am still waiting