I’m no expert here but I think the Cobb Stage 1 is pretty conservative so unless you have some mods I’m thinking bad gas. I only use Mobile or Shell 93. I sometimes see knock but my DAM is 1. Totally stock except for axle backs.

 

Hey, listen... If your DAM is dropping on the regular line you've described, there's something with the tune that's not agreeing with your ecu/motor /build of your car...

Personally, I had issues with my perrin 3p BCS which was contributing to the issue - in the end, I needed my pro-tune redone from scratch after remedying my BCS issue with a new grimspeed BCS... This resolved the issue... I'm pretty close to fbo (w/o AOS or aftermarket IC) I'm catless, running full deletes, stock internals, stock turbo, grimspeed intake & SPT performance exhaust...
(have other none engine mods like clutch, brakes, cosmetics, audio, short shifter, etc)

I fought the DAM issue for months...

I also ran a couple fuel sys cleaners (gumout adv & red line) and that definitely cleaned up some fouled injectors)...

Bottom line, you should find a reputable Tuner and get it sorted out, if running into your regularly...

Also, you should try running shell 93 for 2 full tanks (one tank should have fuel system cleaner like mentioned above) and record of it stops the DAM from dropping - - if it stops then go back to shell 91 for 2 tanks and see if it comes back, before going to a Tuner...

Hello everyone,

I recently purchased my 2016 WRX about a month ago. I'm new to the Subaru world so excuse my little knowledge. I bought a Cobb AP 2 weeks ago and I've been monitoring the DAM gauge. I'm currently tuned on a Stage1 91 v301. Ive been told that it should be at 1.0 always but mine seems to drop and stay low but slowly creep back up. Currently it's sitting at .938 with half a tank left. I've noticed when I get to half a tank it jumps back up slowly. I've been reading forum posts everywhere and can't find a solution besides getting bad gas. There was a post or comment I read somewhere that the FA20DIT engine has DAM drops. I also live in Cali.

 

I'm completely stock at the moment. I've been filling up on 91 Shell/Chevron only. Thinking of trying 93 to see if it helps out if I can find a station with it. Once I buy actual parts for upgrades I'm definitely getting a pro tune. I'm just running the OTS stage 1 map from Cobb atm.

Hey, listen... If your DAM is dropping on the regular line you've described, there's something with the tune that's not agreeing with your ecu/motor /build of your car...

Personally, I had issues with my perrin 3p BCS which was contributing to the issue - in the end, I needed my pro-tune redone from scratch after remedying my BCS issue with a new grimspeed BCS... This resolved the issue... I'm pretty close to fbo (w/o AOS or aftermarket IC) I'm catless, running full deletes, stock internals, stock turbo, grimspeed intake & SPT performance exhaust...
(have other none engine mods like clutch, brakes, cosmetics, audio, short shifter, etc)

I fought the DAM issue for months...

I also ran a couple fuel sys cleaners (gumout adv & red line) and that definitely cleaned up some fouled injectors)...

Bottom line, you should find a reputable Tuner and get it sorted out, if running into your regularly...

Also, you should try running shell 93 for 2 full tanks (one tank should have fuel system cleaner like mentioned above) and record of it stops the DAM from dropping - - if it stops then go back to shell 91 for 2 tanks and see if it comes back, before going to a Tuner...

 

The modern FA purportedly uses the DAM much more actively than prior generations. I've never seen an FA20 ROM, so I'm operating off what others' have posted/said. Subaru's knock control strategy adjusts timing based on modes that are set with specific parameters. The DAM (IAM) has classically been used as the primary timing adjustment for sub-par fuel -- this is sometimes referred to as an Octane Modifier.

The DAM scales back timing globally according to the KCA tables, while FLKC is allowed to feed timing back in on specific load/RPM cells. As the DAM was intended for Octane adjustment, the primary cause of the DAM dropping on a stock motor is likely fuel quality. HOWEVER, chronic DAM scaling can be indicative of vacuum leaks or even oil dilution. With the modern FA20, the DAM's engine mode is reportedly active more of the time, probably as a way to increase the CR of the engine and ride the det-line more effectively.

Some scaling is likely normal. Chronic issues -- i.e. scaling below 1.00 frequently and for long periods of operation -- should warrant further attention.

 

So you're saying I should be fine? And it's normal for the DAM to adjust? I'm pretty sure it's just bad fuel around my area here. I'm monitoring it every time I drive. Currently it jumped back up to 1 and I'm below half of my tank. I'll check if there's any vacuum leaks.

Still learning all this since I'm new to it.

The modern FA purportedly uses the DAM much more actively than prior generations. I've never seen an FA20 ROM, so I'm operating off what others' have posted/said. Subaru's knock control strategy adjusts timing based on modes that are set with specific parameters. The DAM (IAM) has classically been used as the primary timing adjustment for sub-par fuel -- this is sometimes referred to as an Octane Modifier. The DAM scales back timing globally according to the KCA tables, while FLKC is allowed to feed timing back in on specific load/RPM cells. As the DAM was intended for Octane adjustment, the primary cause of the DAM dropping on a stock motor is likely fuel quality. HOWEVER, chronic DAM scaling can be indicative of vacuum leaks or even oil dilution. With the modern FA20, the DAM's engine mode is reportedly active more of the time, probably as a way to increase the CR of the engine and ride the det-line more effectively. Some scaling is likely normal. Chronic issues -- i.e. scaling below 1.00 frequently and for long periods of operation -- should warrant further attention.

 

ive noticed that my 18 wrx does not like closing the egr valve, you have to really put some load on the engine before it will close it off and allow the engine to breathe. i am certain this has caused at least a few of my dam drop instances. so id suggest when in higher gears either accelerate even slower, downshift more often, or at least press the throttle in slower so that the load builds more slowly and hopefully appease the egr gods into letting your car have fresh air so that by the time the load is getting higher your manifold temps are nominal.

 

Thanks for the tip! I'll definitely give that a try when I get my car back next week. Getting my clutch replaced ?