Boost cut?

SamP94 · Apr 21st, 2019, 00:25

My 98 940 2.3 lpt is hitting a boost cut at 0.6 bar(8/9 psi). I have read about people taking the little 13c to 1bar without any issues. Anything specific to check that could be causing this? Or is there any way to bypass it? Or is this normal? Tia

Laird Scooby · Apr 21st, 2019, 10:44

The clue is in the "LPT" bit - Low Pressure Turbo.

Most only run to about 4-6psi from what i understand and the HPT runs to about 8-9psi.

The other question is, do you really mean boost cut? That is controlled by the ECU and (depending exactly how it's set up) cuts the fuel and/or spark when boost exceeds a certain level.

It sounds as if you already have an HPT wastegate in there, allowing it to boost to 8-9psi, i might be wrong on this as i'm not that well up on the turbos - i subscribe to the "there ain't no replacement for displacement" theory!

Mattty · Apr 21st, 2019, 11:21

Are you using a manual boost controller to set the boost?

SamP94 · Apr 21st, 2019, 12:11

Sorry should have mentioned running a manual controller. Definitely some sort of boost/fuel cut just like hitting a wall for a brief moment

Mattty · Apr 21st, 2019, 14:59

Quote:

Originally Posted by SamP94

Sorry should have mentioned running a manual controller. Definitely some sort of boost/fuel cut just like hitting a wall for a brief moment

You're right in your inital post about running the 13c to 1 bar easily, I did so in my LPT without issue. Can you boost past 8/9PSI in any gear? Like drive at 40 in 3rd and do a slow, smooth acceleration to slowly raise the boost?

SamP94 · Apr 21st, 2019, 16:34

Quote:

Originally Posted by Mattty

You're right in your inital post about running the 13c to 1 bar easily, I did so in my LPT without issue. Can you boost past 8/9PSI in any gear? Like drive at 40 in 3rd and do a slow, smooth acceleration to slowly raise the boost?

Unfortunately not, however its driven it will do it. Only way around is to turn the boost back down

Apr 21st, 2019, 00:25	#1
SamP94 Junior Member Last Online: Jun 24th, 2020 13:07 Join Date: Jan 2019 Location: Northampton	Boost cut? My 98 940 2.3 lpt is hitting a boost cut at 0.6 bar(8/9 psi). I have read about people taking the little 13c to 1bar without any issues. Anything specific to check that could be causing this? Or is there any way to bypass it? Or is this normal? Tia

Apr 21st, 2019, 10:44	#2
Laird Scooby Premier Member Last Online: Yesterday 23:44 Join Date: May 2012 Location: Lakenheath	The clue is in the "LPT" bit - Low Pressure Turbo. Most only run to about 4-6psi from what i understand and the HPT runs to about 8-9psi. The other question is, do you really mean boost cut? That is controlled by the ECU and (depending exactly how it's set up) cuts the fuel and/or spark when boost exceeds a certain level. It sounds as if you already have an HPT wastegate in there, allowing it to boost to 8-9psi, i might be wrong on this as i'm not that well up on the turbos - i subscribe to the "there ain't no replacement for displacement" theory! __________________ Cheers Dave Next Door to Top-Gun with a Honda CR-V & S Type Jag Volvo gone but not forgotten........

Apr 21st, 2019, 11:21	#3
Mattty Member Last Online: Jan 1st, 2023 16:44 Join Date: Mar 2017 Location: Blackpool	Are you using a manual boost controller to set the boost?

Apr 21st, 2019, 12:11	#4
SamP94 Junior Member Last Online: Jun 24th, 2020 13:07 Join Date: Jan 2019 Location: Northampton	Sorry should have mentioned running a manual controller. Definitely some sort of boost/fuel cut just like hitting a wall for a brief moment

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