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Is it a boost leak?

Nickpapzdcr

New member
Location
MA
I have a is38 full bolt on APR 93Oct, has everything you can imagine. Only thing is im on stock Diverter valve (which is supposed to be very good still), but i have the new is38 from the new R's with the new diverter valve assembly for only about 9k miles... I did a dyno run yesteday and only put 330 down which is completely off. I have the p3 guage and my tuner saw that my boost at around 5400 was going down to 18psi.... On the street at around that, im making about 23 torward 5500-6000 RPM. I peak at about 30-31. Based on the dyno curve you could see the is38 going up and up and up past 370whp but dropped at 5400 like said. We think it could be the PCV... What do you think? The car feels fine on the road but I dont know what the boost is supposed to hold at, or if its supposed to drop that low. What do you think?
 

Diggs24

Active member
Location
de plains! de plains!
Ride
2015 GTI; 2003 Saab
Then it's not a boost leak as it would happen regardless of street or dyno. Not DV either, same as above. Without logging data it would be impossible to say what happened. Sounds like ECU is protecting the motor. Did you only try 1 pull or was it repeatable?
 

Nickpapzdcr

New member
Location
MA
Then it's not a boost leak as it would happen regardless of street or dyno. Not DV either, same as above. Without logging data it would be impossible to say what happened. Sounds like ECU is protecting the motor. Did you only try 1 pull or was it repeatable?
So APRs new tune which i have has "heat protection" when the motor is hot or something.

FROM APR:
Using a Kistler in-cylinder pressure transducer system, we greatly improved combustion efficiency and reduced in-cylinder combustion pressure while delivering the same output. Furthermore low-RPM torque is now limited in taller gears for greater LSPI protection. Essentially the engine experiences less strain but creates the same power.

Using exhaust gas pressure transducers, thermocouples and turbine shaft speed sensors, we were able to more accurately adjust various speed and pressure models within the ECU, allowing us to reduce turbo shaft speed without sacrificing power. In doing so, boost control was greatly improved. We were able to enable and calibrate various turbo shaft speed protection routines within the ECU that were not enabled or calibrated on all ECU part numbers from the factory. Finally, turbo surge protection routines were recalibrated to prevent low rpm high load compressor surge in various conditions. Essentially boost control is improved, protection routines were added and the turbo doesn’t spin as fast or work as hard to create the same power.


We tried more than 1 pull.
 

Nickpapzdcr

New member
Location
MA
Then it's not a boost leak as it would happen regardless of street or dyno. Not DV either, same as above. Without logging data it would be impossible to say what happened. Sounds like ECU is protecting the motor. Did you only try 1 pull or was it repeatable?
I mean I mean does my psi on the street seem correct/normal?
 

Hoon

Active member
Location
Rhode Island
The apr one
That's a good unit, IATs shouldn't be an issue this time of year it's freezing already.

I mean I mean does my psi on the street seem correct/normal?
Yes.

Depending on how APR has designed their tune, one of the issues could be the difference in load between the dyno and the street. Boost control in our ECU's is load-based, with a calculated torque output and a torque target. I haven't really seen issues on this platform, but on other platforms you will get significantly lower boost on a dyno than the street.
 

Nickpapzdcr

New member
Location
MA
That's a good unit, IATs shouldn't be an issue this time of year it's freezing already.



Yes.

Depending on how APR has designed their tune, one of the issues could be the difference in load between the dyno and the street. Boost control in our ECU's is load-based, with a calculated torque output and a torque target. I haven't really seen issues on this platform, but on other platforms you will get significantly lower boost on a dyno than the street.
Yea I’m not sure though. I ordered a spullen catch can that comes with billet aluminum pcv... bout to find out to see
 

Twist1

Active member
I had APRIS38 For almost 8 months.

I have never seen a number over 28 with that tune. So that is quite strange.
Are you using the analog P3 with the actual boost tap or the OBD2 port one?

It also wasn't even close to 23psi at 6k, more like 14-16 lol

And that is even with no air filter or exhaust so idk
 
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