Boost gauge not reading correctly - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Pneub · 10-29-2013, 06:30 PM

I've got a P3Cars Vent gauge, and while I'm mostly using it to keep track of my oil temps, I've noticed the boost seems to be reading incorrectly. At idle I'm between -18 and -21, which seems about right, but at full boost it's only reading at 4psi when I'm actually boosting about 9. Since it's going through my OBDII I'm not sure why it would be reading so low. What am I missing (probably a lot)?

CSG Mike · 10-29-2013, 06:35 PM

Are you using the stock sensors? It may be maxing out

Pneub · 10-29-2013, 06:38 PM

Quote:

Originally Posted by CSG Mike

Are you using the stock sensors? It may be maxing out

Yes I am but I haven't heard about needing to change the sensors before. Other people with boosted 86s using the same gauge haven't mentioned it. Would I just change my MAF?

xjohnx · 10-29-2013, 06:39 PM

Quote:

Originally Posted by Pneub

Yes I am but I haven't heard about needing to change the sensors before. Other people with boosted 86s using the same gauge haven't mentioned it. Would I just change my MAF?

You need to change your MAP sensor (and get a reflash to accommodate that sensor).

Pneub · 10-29-2013, 06:42 PM

Quote:

Originally Posted by xjohnx

You need to change your MAP sensor (and get a reflash to accommodate that sensor).

Thanks. So does that mean the stock sensor just doesn't read past 4psi?

SmsAlSuwaidi · 10-29-2013, 06:58 PM

Quote:

Originally Posted by Pneub

Thanks. So does that mean the stock sensor just doesn't read past 4psi?

i thought it was 7psi

jamesm · 10-29-2013, 07:01 PM

i got about 5.3psi out of my stock one.

xjohnx · 10-29-2013, 07:10 PM

i believe it's 5.3, but only if your tuner expands the scaling to go that high.

King Tut · 10-29-2013, 07:14 PM

Quote:

Originally Posted by xjohnx

i believe it's 5.3, but only if your tuner expands the scaling to go that high.

This. Also remember that if you do get a different MAP sensor, your tuner needs to adjust the scaling for it or your car might not run.

Pneub · 10-29-2013, 09:11 PM

Quote:

Originally Posted by King Tut

This. Also remember that if you do get a different MAP sensor, your tuner needs to adjust the scaling for it or your car might not run.

Good to know. Thank you guys for all the help again.

bgibbsunc · 10-30-2013, 11:15 AM

I also thought the stock would read up to seven. That is where all the tuners say you will need a map sensor to go higher. Well either way good to know.

Cal3000 · 10-30-2013, 12:39 PM

Quote:

Originally Posted by King Tut

This. Also remember that if you do get a different MAP sensor, your tuner needs to adjust the scaling for it or your car might not run.

This. I have a 3BAR sensor in my car, but my boost readings through ECUtek data log reads a max of about 4psi. My car still runs though.

10-29-2013, 06:30 PM	#1
Pneub Senior Member Join Date: Apr 2013 Drives: Dark Grey BRZ Location: Huntington Beach Posts: 306 Thanks: 172 Thanked 143 Times in 77 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	Boost gauge not reading correctly I've got a P3Cars Vent gauge, and while I'm mostly using it to keep track of my oil temps, I've noticed the boost seems to be reading incorrectly. At idle I'm between -18 and -21, which seems about right, but at full boost it's only reading at 4psi when I'm actually boosting about 9. Since it's going through my OBDII I'm not sure why it would be reading so low. What am I missing (probably a lot)? __________________ Completed build...for now

10-30-2013, 11:15 AM	#11
bgibbsunc Senior Member Join Date: Sep 2012 Drives: Firestorm Scion FR-S Location: United States Posts: 236 Thanks: 80 Thanked 79 Times in 49 Posts Mentioned: 5 Post(s) Tagged: 0 Thread(s)	I also thought the stock would read up to seven. That is where all the tuners say you will need a map sensor to go higher. Well either way good to know. __________________ FA20 club 60 trim + flex fuel 467 whp 356 ft lbs @ 19 lbs Owner of Sidewinders Auto LLC. San Antonio TX

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10-29-2013, 06:35 PM	#2
CSG Mike Join Date: Jul 2012 Drives: S2000 CR Location: Orange County Posts: 14,529 Thanks: 8,918 Thanked 14,175 Times in 6,834 Posts Mentioned: 966 Post(s) Tagged: 14 Thread(s)	Are you using the stock sensors? It may be maxing out

10-29-2013, 07:01 PM	#7
jamesm Banned Join Date: Mar 2013 Drives: 2013 FR-S Location: Orlando, FL Posts: 2,929 Thanks: 1,166 Thanked 2,293 Times in 1,180 Posts Mentioned: 313 Post(s) Tagged: 4 Thread(s)	i got about 5.3psi out of my stock one.

10-29-2013, 07:10 PM	#8
xjohnx Grip>Slip Join Date: Jun 2012 Drives: 13 SWP BRZ Ltd - Innovate Powered! Location: RVA Posts: 3,563 Thanks: 656 Thanked 1,716 Times in 1,031 Posts Mentioned: 45 Post(s) Tagged: 3 Thread(s)	i believe it's 5.3, but only if your tuner expands the scaling to go that high.

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