Does anyone know if the GM MAP sensors read 1 bar?
3400 SWAP DONE. 187WHP 212TQ (14.2 @100MPH NA) 240WHP 310TQ (N2O)
Depends. If you are asking if all GM map sensors are 1-bar, then no. If you are asking if all 3rd Gen J-body map sensors are 1-bar, then yes.
Right.....which map are you refering to. They have the 1 bar, 2 bar, 2.5 bar, 3 bar, 3.7 bar, and perhaps 1 or 2 more.
non boost vehicles don't read past atm pressure......stock boosted vehicles do for the sole purpose of registering boost ex. 3800 s/c.
^ exactly.each "bar" reads about 15psi. So 1 bar would read 0psi to 15psi (which is 0 vaccum) 2 bar reads from 0 psi to 30 psi (which is 15psi of boost)
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^^doesnt it run at -14.7psi which is vacuum and then 0 is normal..so thats one bar..and then 2 bar reads up to 14.7psi and so on.
atm pressure = 1.013 X 10 ^5 PA or 14.7 Psi. hence 1 bar
1 Bar= 14.7psi
1 Bar Map sensor..
The way you see it on guages is that it when it is vented to the air it reads 0psi. Thats because the guage is already calibrated to atmospheric pressure.
So hence, you are running 5psi of boost from a turbo. That means in reality your engine is getting air pressurized at ....
14.7 (atmosphere) + 5 (boost) = 19.7 psi.
A boost guage for example is set up so that 0 is atmospheric, that way it can swing negative of 14.7 (like 10psi which is vaccum) and positive of 14.7 (which is boost)
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umm yes but a 1 bar map does not read above atmospheric...
A 2 bar reads up to 14.7 and so on...
Im wondering about the one on my 3400 that I have in my car now. I have heard from grandamGT.com that they can read 1 bar. Im not sure though because in HP Tuners in the VE section it looks like it can read up to 6psi but that doesnt make sense lol.
3400 SWAP DONE. 187WHP 212TQ (14.2 @100MPH NA) 240WHP 310TQ (N2O)
Simple, if your car isnt stock boost it has a 1 bar map sensor from GM. look into the 3800 s/c map sensor. I am not familar at all with the 3 series motors but im pretty sure the map sensor wiring between the two isn't very much different if different at all.
philly, your missing the point. Atmospheric is 14.7 psi. Therefore, a 1 bar map will read up to 14.7 (closer to 15psi actually). A 2 bar map will read up to 29.4 PSI.
A engine at the pressure of exactly 29.4 psi, is at a boost level of 14.7 psi. Boost implies pressure more than atmospheric. Vaccum implies that it is at a pressure of under 14.7 psi.
Like I said, at 14.7 psi (in the atmosphere) that guage reads 0 psi.
ATMOSPHERIC PRESSURE IS 14.7 PSI, SO A 1 BAR MAP SENSOR WILL READ UP YO 14.7 PSI.
On with the real question... Try the 3800 map sensor.
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SO if i was to put the 3.8 s/c map in would the comp reconize wtf is goin on?
Not without a tune. If it came stock with a 1 bar then when you put a 2 bar sensor in it will read half of what you already have. Both are based on a 5v signal. You have to flash it.
EXAMPLE: At idle, a normal map sensor might make 0.8v. The computer might see that as 35kpa.
With a 2 bar, at idle, the sensor will shown 0.4v. A untunned computer will read that as 17kpa. A computer that knows it has a 2 bar will read 35kpa.
Do you see where this is going? That same concept is used to create a fake 2 bar tune.
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for the sake of this convo, lets just say that atmospheric is 0psi. Because we're talking about boost, not atmospheric pressure. The way you word it is confusing, i had to read it twice to understand. it's correct info, but just worded oddly.....
1 bar map sensors( stock n/a motors) read from -14.7 to 0psi of Boost. You CANNOT us this with a turbo or supercharger.
2 bar map sensors( stock f/i motors) read from -14.7 to 14.7psi of Boost. To go above 14.7psi you need a 3 bar(or 2.5 or whatever you want)
14.84 @ 92.04mph
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RedBird wrote:for the sake of this convo, lets just say that atmospheric is 0psi. Because we're talking about boost, not atmospheric pressure. The way you word it is confusing, i had to read it twice to understand. it's correct info, but just worded oddly.....
1 bar map sensors( stock n/a motors) read from -14.7 to 0psi of Boost. You CANNOT us this with a turbo or supercharger.
2 bar map sensors( stock f/i motors) read from -14.7 to 14.7psi of Boost. To go above 14.7psi you need a 3 bar(or 2.5 or whatever you want)
Exactly what i was saying..
so i just boosted my 00 2.4 cav do i need to switch to a 2 bar map then or will the stock one work with hpt?
Kyle Phillips wrote:so i just boosted my 00 2.4 cav do i need to switch to a 2 bar map then or will the stock one work with hpt?
If you are using a HPT modified version of the Gm supercharger reflash you will need a 2 bar. I can get you the part number for the 2 bar if you need. This would be the best route for you to go.
Edited 1 time(s). Last edited Tuesday, July 15, 2008 6:57 AM
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it's just the pro hpt. but either way i need a 2 bar not the stock one?
thx for your help in advance.
and i am running 5-6 psi with a t3 supper 60 if that matters....
Kyle Phillips wrote:it's just the pro hpt. but either way i need a 2 bar not the stock one?
thx for your help in advance.
Let me clarify here. You now need to find somone with the GM reflash file. Try Wrench Monkey maybe he can help you out. Have whoever has a copy of the GM reflash email it to you and use your HPT to flash it to your car. The GM reflash is a programmed for 2 bar. Without the gm reflash the ECU can not make sense of what the 2 bar is telling it. I am not sure what you are using for injectors but some 310cc's are what the reflash it setup for so I would start tuning with those. With HPT you will have no need for FMU or AFPR
What you have now would be a stock 1 bar gm tune that can only read from a 1 bar map sensor. Basically if you have a 1 bar tune you need a 1 bar map, if you have the gm reflash which is for a 2 bar you need a 2 bar map sensor.
You are going to need a 2 bar map sensor as well as the GM sc reflash.
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ok what if i were to get a 2 bar map, then took it to a dealer to get reflashed. would that work untill i get it looked at by someone with hpt? or do i need to still not boost till i get it retuned with hpt.
i have a friend with hpt and he hasn't done ne turbo cars but thinks he can get it runnin pritty good he does the cobolts ss/sc's. but if i get it reflashed will he have a base to go by or would it still be a blind street tune with a wide band?
Kyle Phillips wrote:ok what if i were to get a 2 bar map, then took it to a dealer to get reflashed. would that work untill i get it looked at by someone with hpt? or do i need to still not boost till i get it retuned with hpt.
i have a friend with hpt and he hasn't done ne turbo cars but thinks he can get it runnin pritty good he does the cobolts ss/sc's. but if i get it reflashed will he have a base to go by or would it still be a blind street tune with a wide band?
For the 5 psi you are running the GM supercharger reflash is a great base. The timing and afr are rather conservative. GM chose to error on the side of safety.
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