Changing from a 2bar map to a 3bar map?
12-17-2006, 08:12 PM
#1
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Changing from a 2bar map to a 3bar map? If everything has been tuned with a 2bar map and you install a 3bar map, is the 0 - 2 bar tune valid? Part throttle, etc. Just change the scalar and tune for the cells above the original 2bar tune? TIA
12-18-2006, 12:47 AM
#2
In a perfect world, maybe, but the different output values and loss of resolution with a 3bar map are going to make a full retune necessary. The slight output variations that are within quality control standards for any given sensor are negligible on a 1bar, but with a 3bar's resolution it could be an issue.
12-18-2006, 06:38 PM
#6
There is no such thing as 30 lbs of vacuum. Map sensors read from 0 kilopascals pressure, which is about -15psi, and they have a range which is referred to in bars, or barometric pressure. A 1bar sensor can read from approximately -15psi to 0psi, a 2bar from -15 to +15, and a 3bar from -15 to +30psi. These are of course approximations of psi, as the sensors are calibrated for kilopascals, and I don't feel like looking up the metric to standard conversion charts.
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12-18-2006, 07:02 PM
#9
Opps i forgot to factor in the atmosphere that we automatically never see.
1 bar is -44.1psi to -14.7. So if you add atmospheric pressure to that " which we all do" it is -30 to 0
3 bar is -14.7psi to 44.1psi, BUT AFTER YOU TAKE AWAY ATMOSPHERIC PRESSURE it is only 0 to 30 psi on our car....
1 bar is -44.1psi to -14.7. So if you add atmospheric pressure to that " which we all do" it is -30 to 0
3 bar is -14.7psi to 44.1psi, BUT AFTER YOU TAKE AWAY ATMOSPHERIC PRESSURE it is only 0 to 30 psi on our car....
12-18-2006, 07:10 PM
#10
The sensors do not have the same range. A 1bar has about 0-105kp range. A 2bar has about 0-210kp range. A 3bar has about 0-315kp range. The extended range of the higher pressure sensors is still handled with a 0-5volt output signal, which is why resolution is lost. I'm now going to give up on this extended thread hijack.
12-19-2006, 08:58 AM
#11
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Talked to the engineer at Delphi.
The GM# 12223861 (From the 1989TTA) is still a valid part number and is the best 3 bar map they make due to the lower kPa resolution. This map will read from 40 to 304 kPa. Good for 28psi of boost and since it does read below 100kpa it should tune in ok for part throttle. Go here for the tech specs.
http://www.powerandsignal.com/docs/P...s/12223861.pdf
The GM# 12223861 (From the 1989TTA) is still a valid part number and is the best 3 bar map they make due to the lower kPa resolution. This map will read from 40 to 304 kPa. Good for 28psi of boost and since it does read below 100kpa it should tune in ok for part throttle. Go here for the tech specs.
http://www.powerandsignal.com/docs/P...s/12223861.pdf
12-19-2006, 10:38 AM
#12
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all of those sensors that read different pressures, all report that data as a voltage from 0-5V or whatever. ( I dont rememeber if its +-5 so go easy on me!) 
the PCM needs to know that the 5v range on a one bar = 105kpa and that 5v on a 2 bar =210kpa, etc.
in other words, you need a different OS, to match the calibration of the sensor.
(I know I might have my signs and range messed up, but you get the idea)
so if you slap a 2 bar sensor in a 1 bar OS PCM car, when you hit 105kpa MAP, the PCM will expect to see 5v, but instead will see 2.5v, and think your only at 55kpa or whatever (im assuming the relationship between volts and kpa is linear, if not shoot me)
the PCM needs to know that the 5v range on a one bar = 105kpa and that 5v on a 2 bar =210kpa, etc.
in other words, you need a different OS, to match the calibration of the sensor.
(I know I might have my signs and range messed up, but you get the idea)
so if you slap a 2 bar sensor in a 1 bar OS PCM car, when you hit 105kpa MAP, the PCM will expect to see 5v, but instead will see 2.5v, and think your only at 55kpa or whatever (im assuming the relationship between volts and kpa is linear, if not shoot me)
12-23-2006, 09:31 PM
#13
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Oh GAWDDDDDDDDDDDDDDDDDDDD
Fire shooting out of the tailpipes.....roasted 2 pet kittens
Actually all is good. Biggest tip is to get the scalar set to key on engine off to your actual kPa. It was only a little richer than the 2bar at part throttle. Dead on at WOT. Drove great on the 2bar tune....I'll fine tune it tomorrow.
Delphi 3bar part number 12223861 sold by Speed Inc under the FAST brand and many others...great low end resolution.....don't waste your time or money on a 2 bar map like I did.
Fire shooting out of the tailpipes.....roasted 2 pet kittens
Actually all is good. Biggest tip is to get the scalar set to key on engine off to your actual kPa. It was only a little richer than the 2bar at part throttle. Dead on at WOT. Drove great on the 2bar tune....I'll fine tune it tomorrow.
Delphi 3bar part number 12223861 sold by Speed Inc under the FAST brand and many others...great low end resolution.....don't waste your time or money on a 2 bar map like I did.
12-23-2006, 09:58 PM
#14
Originally Posted by onfire
don't waste your time or money on a 2 bar map like I did.
If someone has a clear answer why to use 2 bar over 3 I'd like to know for my own sanity.
12-24-2006, 06:58 PM
#16
like i said as long as you keep the same resolution I don't see a point in going with a 2 bar setup if theres even a slight chance. How much accuracy do you actually loose though by going with a 3 bar rather then a 2 bar?
ps im not arguing the point, I'd actually like to have the answers to this stuff as well as others im sure
ps im not arguing the point, I'd actually like to have the answers to this stuff as well as others im sure
12-24-2006, 07:13 PM
#17
As i said in post 5. Each Sensor can only be ACCURATE in certain ranges.
Think of it exactly like the secondary VE table we have. Using that to tune for a big motor and boost.
We have the main cells there, but the resolution sucks. Same thing goes for map sensors. if you use one that is out of the range of your vehicle then it is harder to get correct in the full area. 0-5 volts is all it has to spread itself accross. So the more you have to shove into that area the harder it is to correct.
Think of it exactly like the secondary VE table we have. Using that to tune for a big motor and boost.
We have the main cells there, but the resolution sucks. Same thing goes for map sensors. if you use one that is out of the range of your vehicle then it is harder to get correct in the full area. 0-5 volts is all it has to spread itself accross. So the more you have to shove into that area the harder it is to correct.
12-24-2006, 07:28 PM
#18
Originally Posted by wait4me
As i said in post 5. Each Sensor can only be ACCURATE in certain ranges.
Think of it exactly like the secondary VE table we have. Using that to tune for a big motor and boost.
We have the main cells there, but the resolution sucks. Same thing goes for map sensors. if you use one that is out of the range of your vehicle then it is harder to get correct in the full area. 0-5 volts is all it has to spread itself accross. So the more you have to shove into that area the harder it is to correct.
Think of it exactly like the secondary VE table we have. Using that to tune for a big motor and boost.
We have the main cells there, but the resolution sucks. Same thing goes for map sensors. if you use one that is out of the range of your vehicle then it is harder to get correct in the full area. 0-5 volts is all it has to spread itself accross. So the more you have to shove into that area the harder it is to correct.
12-24-2006, 08:04 PM
#19
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Originally Posted by wait4me
As i said in post 5. Each Sensor can only be ACCURATE in certain ranges.
Think of it exactly like the secondary VE table we have. Using that to tune for a big motor and boost.
We have the main cells there, but the resolution sucks. Same thing goes for map sensors. if you use one that is out of the range of your vehicle then it is harder to get correct in the full area. 0-5 volts is all it has to spread itself accross. So the more you have to shove into that area the harder it is to correct.
Think of it exactly like the secondary VE table we have. Using that to tune for a big motor and boost.
We have the main cells there, but the resolution sucks. Same thing goes for map sensors. if you use one that is out of the range of your vehicle then it is harder to get correct in the full area. 0-5 volts is all it has to spread itself accross. So the more you have to shove into that area the harder it is to correct.
But your post number 5 is wrong. I have the engineering drawing from Delphi on this map sensor.(#12223861)
You're saying a 3bar map will not read below 100kPa. This one is rated down to 40kPa and reads down to 25kPa in my car. Obviously, if all you want is 14.7psi a 20 to 200kPa (2bar) map is all you'll need and if you want a commanded cruise AF of 14.7:1 to be absolutely perfect a 2bar map is better at the final 0.10 digit. However, If 14.6:1 works for ya even though you've commanded 14.7 , this 3 bar is fine. It's rated at 40 to 304kPa. What VooDoo can you use with a 2bar at 20psi....back to RPM vs PE????????