Understanding DAM

So I recently purchased an AP and installed it with a stage 1 power tune. One of my buddies semi went over DAM readings and said it should be at 1.000 at all times. I loaded guages and it was staying there with the stage 1 power tune on feeling very healthy. The tune was for 91 octane and today I get on the highway and start driving and feel almost a hesitation up the hill. Then my DAM goes to 0.000 so I get a little worried. I pull over and check for intake or vacuum leaks as those were my usual suspect but cant find any. Car still built boost okay peaking at 16 psi in sport sharp. I loaded the stock map back on in worry for my cars safety and now I'm just trying to understand in depth what's happening? I've read some cases bad tanks of gas can cause this but mostly it has to deal with knock learning and such. I have no check engine lights which is odd but the car is a 08 spec b with 120k miles. Any input is greatly appreciated

Is this a protune or Cobb’s off the shelf tune?

Cobbs off the shelf tune

Update, I loaded the stock tune back on, then reloaded the stage 1 after a drive cycle and after some driving and a subtle little pull the DAM is back to 1.000. Curious as to what's happening

if this is a v3, monitor Feedback Knock, Fine Knock Learn, AF correction and AF Learning. If you see any large +/- spikes in either of these values while driving, start logging and post it.

 

If you need a list of parameters to include in datalogging, I can provide a list that most tuners use or just search it up. The less parameters, the easier it is to read.

 

Bad gas and false knock from a rattling heat shield could trigger DAM to drop but I’ve never heard it drop to 0 from those alone. However it could also be a faulty knock sensor or a loose bolt or something near cylinder 4 that is triggering it.

 

Any other recent mods, or any since you’re Stage 1?

Edited January 11, 2019 by Notorious

It is a v3 so I'll have to add those. I'm new to this world so the data logging will be a learning curve.

 

As for the car I actually noticeably have loose heat shields on the downpipe that rattle a bit on down rev but not really loud. As for the mods it has nothing in the engine just a 3inch stainless catback exhuast. Shortly I'll be installing an aftermarket downpipe for stage 2 and to also remedy the rattle but I dont want to push my car for my power if it's not safe to do so.

 

The moment the DAM went back up was after a fill up with fresh premium in the tank as I was a little low. Is there a possibility I could be in need of some heet in the gas tank being that its mid winter up in the pnw? My dads always told me that condensation can cause water deposits in the tank/lines so running a 2$ bottle of heat in the tank every once on awhile isnt a bad idea

It is a v3 so I'll have to add those. I'm new to this world so the data logging will be a learning curve.

 

As for the car I actually noticeably have loose heat shields on the downpipe that rattle a bit on down rev but not really loud. As for the mods it has nothing in the engine just a 3inch stainless catback exhuast. Shortly I'll be installing an aftermarket downpipe for stage 2 and to also remedy the rattle but I dont want to push my car for my power if it's not safe to do so.

 

The moment the DAM went back up was after a fill up with fresh premium in the tank as I was a little low. Is there a possibility I could be in need of some heet in the gas tank being that its mid winter up in the pnw? My dads always told me that condensation can cause water deposits in the tank/lines so running a 2$ bottle of heat in the tank every once on awhile isnt a bad idea

 

If your loose heat shields is noticeably audible from inside the cabin, I would say that this is probably 90% chance the cause of your issue. Issues with bad gas would have happened when you flashed back to the stock map as well and would consistently give knock issues.

 

I would like to believe that when you were on the incline, the heatshields were in a position to rattle like crazy and trigger the knock sensor. Probably a good idea to tighten those up. Not ruling out other possible causes but this would be the easiest to test after you fix the shields.

Okay awesome thank you. So out of curiosity what is DAM? Is it basically a knock sensor that pulls back timing advancements when its detects pings?

Hey there,

 

Are you sure you were looking at DAM and not Dynamic Advance?

 

You should not be able to hit over 8psi if DAM was at 0.00 as it disables boost control. I have had quite a few customers mix up DA and DAM....

 

Hope that helps.

 

Dave

https://www.cobbtuning.com/subaru-knock-monitoring-and-dit-knock-logic-changes/

 

Tons of info on Cobb's website.

It is in fact the DAM. On the AP it says Dyn. Adv. Mult. And that would make sense as the car was struggling/hesitating a bit to get up the hill I was currently going up. Its weird as now the car is behaving normally, acting quite normal staying at 1.000 as should and building boost properly. I'll be replacing the downpipe soon and I'll have to check the condition of the knock sensor

I was on the highway and noticed the DAM dropped again, this time just to 0.875, so I started logging but I'll be honest I have no idea what I'm doing so I just logged the accessport for my regular commute. Do you have to have it hooked up to a computer or something?

 

Anyways I noticed if I was in 6th gear and the car started to go up a hill or take on a higher load then the feedback knock would go into the negatives. Afr learning was constantly changing so hard to get a number on it. I've attached a picture of the high and low just to kinda provide some bit of info that I can

 

Weirdly enough once I gave it a solid pull in just sport mode the DAM hopped back up to 1.000. It seems the DAM is dropping whenever I do a pull in sport sharp

 

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My wagon does not like low end load esp in higher gears. Downshifting and keeping revs in their happy place is a good idea, btw 2500-4000rpms.

When you take a log (like you did on your drive to work) you then have to hook up your AP to a computer and download that log in order to learn much of anything.

 

Cobb's website has tons of info about parameters to log and how to's as well.

May be time to take a look at your intake and see of you have excessive oil accumulating.

More oil in the intake than usual will degrade the fuel mix and force the ECU to pull timing.

I was fighting this for a bit and after placing an AOS and new PCV it's been rock solid.

Plus make sure there are no vacuum leaks or problems with the intake plumbing.

What kind of fuel (Octane and gas station) are you running?

 

Any mods to the car at all?

Okay cool I'll have to find a computer. As for the intake I'll have to take a look. I want to say the plumbing should be okay as well as vacuum leaks as normally I would get a cel from that and the car doesnt have a cel. I'll try the starting fluid trick and see what I can find

 

As for the fuel its 92 octane and I usually get gas at Safeway as it's on my way home, I'm not too sure what brand the gas is. I've also gotten shell often and the car reacts fine on both kinds. The car is just a stage 1 ots cobb tune with a 3 inch catback exhuast but nothing else really

Okay cool I'll have to find a computer. As for the intake I'll have to take a look. I want to say the plumbing should be okay as well as vacuum leaks as normally I would get a cel from that and the car doesnt have a cel. I'll try the starting fluid trick and see what I can find

 

Make no assumptions. You really want to determine engine health and status before you start masking things with tuning. Among other things, can have air leaks that will not produce check engine lights.

 

Did you happen to record any data prior to flashing the ECU? How were fuel trims then and how was DAM?

 

I’d get your rattles fixed and make sure everything is ok but I’m guessing that isn’t going to be the absolute cure. My guess is that you have real knock and you’re going to want to address it.

I actually didnt log any data before the tune. That's my hope is that it's just a rattle but I'm with you, scared something is actually happening to it. My plan is going to be to do the heatshields first, then check for vac leaks with starting fluid, pull intake and make sure its clean, check PVC valve, locate and check knock sensor. Then if that doesnt fix it it'll be a bit beyond me and will take some digging. Anything I should add to that list?

I actually didnt log any data before the tune. That's my hope is that it's just a rattle but I'm with you, scared something is actually happening to it. My plan is going to be to do the heatshields first, then check for vac leaks with starting fluid, pull intake and make sure its clean, check PVC valve, locate and check knock sensor. Then if that doesnt fix it it'll be a bit beyond me and will take some digging. Anything I should add to that list?

 

Flash it back to stock while you’re trying to fix the other things. Record some data, get a baseline to figure out if the software is hurting you or not.

How do you flash back to stock? Theres the option to remove the accessport which flashes to stock but then I cant view any of the data logging stuff. I cant find the option to reflash back to stock either?

How do you flash back to stock? Theres the option to remove the accessport which flashes to stock but then I cant view any of the data logging stuff. I cant find the option to reflash back to stock either?

 

Cobb has the stock map available for download on their website.

As for the fuel its 92 octane and I usually get gas at Safeway as it's on my way home, I'm not too sure what brand the gas is. I've also gotten shell often and the car reacts fine on both kinds. The car is just a stage 1 ots cobb tune with a 3 inch catback exhuast but nothing else really

 

Try to stick to TopTier gas stations, I personally only use Shell and have very good luck with it locally. Try a full tank of TopTier or Shell gas next and see if it still knocks. If you don't have access to 93, make sure you run the 91 stage 1 map!

 

Catback exhaust will change Volumetric Efficiency, which in turn requires less timing. Cobb tune might be more aggressive then stock, thus leading causing knock on their Stage 1 tune but not on stock tune.

 

To go back to stock, you can uninstall the AP, but that might not let you read the values anymore, so try what NewEraHanz suggested first.

I really need to get a damn computer lol. I'll see if I can borrow somebody's to get things situated and update you guys as things progress. Thank you all for the info, I appreciate the knowledge very greatly

BtSsm app and a cable is all you need to log and do it really easily. Available thru PlayStore with any decent Android device. I use it pretty much every day on my phone to keep an eye on things.

 

I bet your issue is something easy. Go over your list, get your baselines and reset your map to a stg1 91oct map, but run 91oct or better. Give you a little extra margin of error if so. Keep your revs a little higher, btw 2500-4000rpms esp shifting under load.

 

I reset my ECU today bc I hadn't since mid summer, so maybe to adjust to any winter fuel (mpg dropped lately) and the temps seem to be consistently colder esp in the AM. I watch BtSsm every day and things looked ok, but after the reset and some idle relearning my wagon was right back up to 1.000 IAM and logging looked clean.