Tag Archives: AccessPort

Subaru Knock Monitoring – Cobb Tuning

I read Cobb Tuning’s Facebook postings and saw the following the other day:  http://www.cobbtuning.com/subaru-knock-monitoring-and-dit-knock-logic-changes/

Most people that have turbocharged Subarus and either have a Cobb Accessport or want one always ask how does one monitor for knock.  I’ve elaborated on this in the past (here) but the information in the link comes straight from the source!


Detonation events are inevitable and will occur from time to time on any modern vehicle running on pump gas.  Your car is built to recognize these events and take the appropriate action to defend against them causing any damage.  The Subaru knock detection system tends to err on the side of caution.  This makes it common to see “false knock.”  False knock occurs when the ECU corrects for a knock event but the noise registered is due to other noises that aren’t necessarily detonation or harmful to the engine.  This often happens accelerating from a stop while letting the clutch out, during gear shifts (more so if grunting while shifting), accelerating at low RPM in a high gear, under cruise on the freeway, and during abrupt throttle changes.

Read the rest at the above hyperlink.  Enjoy!

Cobb Tuning – Researching AP v3 for Subaru STI

So, I’m conducting research on the Cobb AP just so I can make an informed decision on if this would be a good idea for my car.  The latest version of the AccessPort is expensive ($650), but the v3 offers a lot more functionality than the v2, so this may be what I’ll get.

In today’s research (this will take awhile), I saw the following:

http://www.cobbtuning.com/Dyno-Database-s/70119.htm, then select “Han Wu”


This guy already has a rather strong STI (248HP/254TQ at the wheels).  When Stage 1 OTS was applied, the dyno read 269HP/319TQ).  From there, he got a protune while still at Stage 1, netting 276HP/327TQ.

If you click on all three dyno runs, you can see the differences between the three (there will be six graphs).  In particular, look at the stock and the Stage 1 OTS graphs.  Two things are apparent:  1.  There are a several big dips in both the HP and torque graphs on the stock dyno run; 2.  There are huge gains in the OTS map (21HP and 64TQ peak).  The last set of graphs looks to be where the owner decides to go Stage 1 protune (at 18.5 psi), where a few more HP and TQ are squeezed out.

The dyno session started at 9:30AM and ended at 10:11AM (granted, the work wasn’t much, as they went from stock to S1 OTS then protuned off of that).  IMO, that’s a significant gain and the session probably costed $300 (not sure where the tune was done).

PTuning is near me (in Manassas, VA), and I’m pretty sure they do protuning…I’ll check their rates.  I’ll also check their site to see their pricing on a Cobb AP and what they charge for a tune.