Low Boost on 991.2 Base
10-05-2021, 09:23 PM
#1
Rennlist Member
Thread Starter
Low Boost on 991.2 Base
I have a base 991.2 (non-S) and recently had a major service done at the dealer, plugs, air filter, oil.
After getting it back, it feels slightly down on power. According to the gauge, the maximum boost is 0.7 bar or 10 PSI, after a series of 3rd gear pulls. I never really paid attention to the boost gauge before, but I swear it was higher.
I took it back to the dealer and they checked everything and couldn't find any loose hoses, no codes, etc. They measured a maximum boost of 1750 hPa, which translates to 1.750 bar absolute or 0.750 relative, which is about 11 PSIG by my calculations.
I read here on the forums that there are some vacuum lines that need to come off when changing out the air filter, if that was not connected, would this cause the issue?
If anyone else has a 991.2 base, what is your maximum indicated boost?
After getting it back, it feels slightly down on power. According to the gauge, the maximum boost is 0.7 bar or 10 PSI, after a series of 3rd gear pulls. I never really paid attention to the boost gauge before, but I swear it was higher.
I took it back to the dealer and they checked everything and couldn't find any loose hoses, no codes, etc. They measured a maximum boost of 1750 hPa, which translates to 1.750 bar absolute or 0.750 relative, which is about 11 PSIG by my calculations.
I read here on the forums that there are some vacuum lines that need to come off when changing out the air filter, if that was not connected, would this cause the issue?
If anyone else has a 991.2 base, what is your maximum indicated boost?
10-05-2021, 10:56 PM
#2
Rennlist Member
I have a Carrera T, no tune, but Soul Hi Flow Sport Cars.
Max boost indicated is 12 psi, but only for a second or less, drops to 10-11psi almost immediately..
Butt dyno says it’s faster, of course😎, but sound is definitely improved as many here who have hi flow cats have reported.
Let us know what you find out.
Max boost indicated is 12 psi, but only for a second or less, drops to 10-11psi almost immediately..
Butt dyno says it’s faster, of course😎, but sound is definitely improved as many here who have hi flow cats have reported.
Let us know what you find out.
10-06-2021, 05:59 AM
#4
I would be upset if I had work done to improve the car but got it back with less power. On my base 991.2 I could hit 13psi but since I upgraded the headers, sport cats, exhaust, air filter I can only hit 12psi. It feels faster than stock though. So less restrictions makes more power without needing that 1 extra psi.
10 psi is way to low even for a base! Something is not right. Have a Indy shop take a second look or another dealer.
10 psi is way to low even for a base! Something is not right. Have a Indy shop take a second look or another dealer.
10-06-2021, 09:29 AM
#5
Could be a couple things but it sounds like cold weather is probably the culprit if your in a zone that has started to cool down. The colder the ambient air the easier for the engine to hit torque targets and less the turbo has to work and therefore less pressure, also the turbo works off of the exhaust gases (hotter is better) so if the underside of the car is being chilled by the ambient air the turbo air is condensed more so than hotter air theoretically causing less boost. The other thing is the Bosch diverter valves are known for having issues, that could cause the vehicle to not have as much boost pressure too. If the car is under warranty, I’d probably have them look at the diverter valves, if there hasn’t been a big temperature change.
Last edited by smgkc; 10-06-2021 at 09:39 AM.
10-06-2021, 10:26 AM
#6
Rennlist Member
I have a 2017 base and I was having a hard time getting 12psi from my car. I replaced both diverter valves and boost would go to 14 and hold there. Once I got a Softronic tune it would go to 15 and peg the gauge. It will do that when the temp is below 50 degrees so I don't think it is so much temp related. I think the gauge only goes to 15psi on the base. Possible it is the diverter valves if there is no other leak.
10-06-2021, 01:17 PM
#7
Could be a couple things but it sounds like cold weather is probably the culprit if your in a zone that has started to cool down. The colder the ambient air the easier for the engine to hit torque targets and less the turbo has to work and therefore less pressure, also the turbo works off of the exhaust gases (hotter is better) so if the underside of the car is being chilled by the ambient air the turbo air is condensed more so than hotter air theoretically causing less boost. The other thing is the Bosch diverter valves are known for having issues, that could cause the vehicle to not have as much boost pressure too. If the car is under warranty, I’d probably have them look at the diverter valves, if there hasn’t been a big temperature change.
