Voltage cap for MAP 2.2L - Subaru Impreza GC8 & RS Forum & Community: RS25.com

NC_OBS · 06-09-2009, 07:52 AM

Just wondering at what voltage comming out of the MAP sensor a 2.2L will trip a CEL/Stutter and have problems(saay under forced induction) Found a 5.1v Zener diode at radio shack and I was wondering if this is going to be too high and give my car troubles when I hit the boost.

**Skidd** · 06-09-2009, 08:00 AM

I'm afraid I don't have a definitive answer for you.
All I can say is I have my 2.5L MAP clamped at 4.6v.
And, I don't think the 5.1v will work, since the source voltage to the sensor is only 5.0v. So, technically, it's impossible to ever get to 5.1v.

susiemk · 06-09-2009, 08:09 AM

Yup.

To get the clamp level perfect you will have to measure voltage output fron the MAP sensor @ WOT to determine the proper voltage level for YOUR car.

NC_OBS · 06-09-2009, 08:51 AM

I see, will it come out the same at WOT sitting in the driveway as on the highway? Or will I have to figure out some way to check the voltage while I'm driving at WOT? cause that'd be tricky.

**Skidd** · 06-09-2009, 08:55 AM

haha.. actually.. it's easier than you think!!
Turn your key to ON, but do NOT start the car.
You don't even have to worry about opening the throttle.
With the car not running, it will be reading atmospheric pressure.
This is pretty much the same/max you'd ever get with WOT.
Check the voltage, there is your WOT 0inHg voltage signal.
Keep in mind, your MAP is absolute pressure, so the high Voltage value will be different at sea-level in say.. San Diego, compared to Denver. You want to try and find the value in San Diego, since the value in Denver would be lower.

NC_OBS · 06-09-2009, 10:04 AM

Well I'm in central North Carolina, so that oughta be close enough to sea level

Thanks by the way for all the quick answers on this thread and my "SC Health" thread!

susiemk · 06-09-2009, 11:42 AM

Quote:

Originally Posted by Skidd

haha.. actually.. it's easier than you think!!
Turn your key to ON, but do NOT start the car.
You don't even have to worry about opening the throttle.
With the car not running, it will be reading atmospheric pressure.
This is pretty much the same/max you'd ever get with WOT.
Check the voltage, there is your WOT 0inHg voltage signal.
Keep in mind, your MAP is absolute pressure, so the high Voltage value will be different at sea-level in say.. San Diego, compared to Denver. You want to try and find the value in San Diego, since the value in Denver would be lower.

+1

You just need to record voltage for your car @ 0PSI / mm-HG.
The easiest way to measure voltage MAP Voltage @ 0PSI is what is stated above!

President_Douche · 06-10-2009, 07:44 PM

not to hijack but....

do i need to run a map clamp on my 97 MAF car? it has the map sensor fender mounted and im using a check valve just so it doesn't see boost... althought its throwing another map CEL code.... out of range or something

or will the map not care on this cars since its MAF based?

**Skidd** · 06-10-2009, 10:05 PM

You have a 97MAF car that also has a MAP?
That seems odd to me.
I know the factory turbo cars have both, but the older NA cars?

President_Douche · 06-11-2009, 05:47 AM

Yup... have the MAF in the intake track... or well use to be, now its before my turbo and have a map sensor fender mounted infront of the passenger strut

06-09-2009, 07:52 AM	#1 (permalink)
NC_OBS 2.0L Car: 2000 Outback Sport My: Subaru Parts Join Date: Apr 2009 Location: Raleigh, NC Trader Rating: (0) Posts: 67	Voltage cap for MAP 2.2L Just wondering at what voltage comming out of the MAP sensor a 2.2L will trip a CEL/Stutter and have problems(saay under forced induction) Found a 5.1v Zener diode at radio shack and I was wondering if this is going to be too high and give my car troubles when I hit the boost.

06-09-2009, 08:00 AM	#2 (permalink)
Skidd Elite Moderator Car: '00RS+'04FXT Fav Mod: Supercharger My: Subaru Parts My: Subaru Blog Join Date: Dec 2001 Location: SA-TX (Hoser Expat) Trader Rating: (3) Posts: 5,319	I'm afraid I don't have a definitive answer for you. All I can say is I have my 2.5L MAP clamped at 4.6v. And, I don't think the 5.1v will work, since the source voltage to the sensor is only 5.0v. So, technically, it's impossible to ever get to 5.1v. __________________ No no, light speed is too slow! We need LUDICROUS SPEED! (now in Supercharged flavor)

06-09-2009, 08:55 AM	#5 (permalink)
Skidd Elite Moderator Car: '00RS+'04FXT Fav Mod: Supercharger My: Subaru Parts My: Subaru Blog Join Date: Dec 2001 Location: SA-TX (Hoser Expat) Trader Rating: (3) Posts: 5,319	haha.. actually.. it's easier than you think!! Turn your key to ON, but do NOT start the car. You don't even have to worry about opening the throttle. With the car not running, it will be reading atmospheric pressure. This is pretty much the same/max you'd ever get with WOT. Check the voltage, there is your WOT 0inHg voltage signal. Keep in mind, your MAP is absolute pressure, so the high Voltage value will be different at sea-level in say.. San Diego, compared to Denver. You want to try and find the value in San Diego, since the value in Denver would be lower. __________________ No no, light speed is too slow! We need LUDICROUS SPEED! (now in Supercharged flavor)

06-10-2009, 10:05 PM	#9 (permalink)
Skidd Elite Moderator Car: '00RS+'04FXT Fav Mod: Supercharger My: Subaru Parts My: Subaru Blog Join Date: Dec 2001 Location: SA-TX (Hoser Expat) Trader Rating: (3) Posts: 5,319	You have a 97MAF car that also has a MAP? That seems odd to me. I know the factory turbo cars have both, but the older NA cars? __________________ No no, light speed is too slow! We need LUDICROUS SPEED! (now in Supercharged flavor)

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06-09-2009, 08:09 AM	#3 (permalink)
susiemk 2.2L Turbo Car: '99 OBS-t, '00 Leg, '94 LSS Fav Mod: ej222+8psi=13.8 1/4's My: Subaru Parts Join Date: Jul 2006 Location: NYC Trader Rating: (49) Posts: 2,977	Yup. To get the clamp level perfect you will have to measure voltage output fron the MAP sensor @ WOT to determine the proper voltage level for YOUR car.

06-09-2009, 08:51 AM	#4 (permalink)
NC_OBS 2.0L Car: 2000 Outback Sport My: Subaru Parts Join Date: Apr 2009 Location: Raleigh, NC Trader Rating: (0) Posts: 67	I see, will it come out the same at WOT sitting in the driveway as on the highway? Or will I have to figure out some way to check the voltage while I'm driving at WOT? cause that'd be tricky.

06-09-2009, 10:04 AM	#6 (permalink)
NC_OBS 2.0L Car: 2000 Outback Sport My: Subaru Parts Join Date: Apr 2009 Location: Raleigh, NC Trader Rating: (0) Posts: 67	Well I'm in central North Carolina, so that oughta be close enough to sea level Thanks by the way for all the quick answers on this thread and my "SC Health" thread!

06-10-2009, 07:44 PM	#8 (permalink)
President_Douche 2.2L Car: Black 97 Impreza L 2Door Fav Mod: Turbo! My: Subaru Parts Join Date: Mar 2009 Location: 31537 Trader Rating: (0) Posts: 158	not to hijack but.... do i need to run a map clamp on my 97 MAF car? it has the map sensor fender mounted and im using a check valve just so it doesn't see boost... althought its throwing another map CEL code.... out of range or something or will the map not care on this cars since its MAF based?

06-11-2009, 05:47 AM	#10 (permalink)
President_Douche 2.2L Car: Black 97 Impreza L 2Door Fav Mod: Turbo! My: Subaru Parts Join Date: Mar 2009 Location: 31537 Trader Rating: (0) Posts: 158	Yup... have the MAF in the intake track... or well use to be, now its before my turbo and have a map sensor fender mounted infront of the passenger strut

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