[ntippet]

Yep you are spot on with regards to decreased duty cycle when speed increases.
Not much need to keep pressure high if they will be spinning the same speed for typical on road use.
Advanced detection of slip would be the key here.
I am curious how fast the reaction will be when I test it in the snow.

The stall test isn't necessary, I believe the KOEO in gear, throttle pinned will accomplish the same thing.
Although there will be no pressure in the system just solenoid activation.
If you listen under the vehicle you can actually hear the solenoid buzzing at 50Hz.
I have heard some people incorrectly diagnosing a bad solenoid because they "think" it sounds bad with the buzzing. Its normal.

The peak is hard to see, I would have to throw a scope on it to capture it.
My DVOM does have a max value capture though, have to look at the manual but I believe it captures as low as 1ms.
I haven't viewed the values in FreeSSM long enough to notice how fast it is refreshing.

I will have to observe the conditions under which the line pressure solenoid frequency changes.
Haven't dug into it that much yet but, it was definitive and pronounced. All solid #'s 50,100 & 150.
The transfer solenoid and TCC never deviate from 50.
Will check again on the 2-4B Solenoid, didn't seem right to me that it was the odd man out either.

The link you posted to the cable is the exact one I bought. :29:

 

[plain OM]

. . .. I monitored the AWD solenoid pressure, so keep in mind that the results were converted into kPa by freessm.. . .
. . . It got to around 360kPa at half throttle in 1st gear. . . .. When coasting to a stop, it stayed at 30kPa. From a stand still, it starts off at 120kPa. WOT in 5th gear got it up to 100kPa. I know the line pressure for the transmission can get over 1100kPa, but I don't know if the transfer solenoid will get that high.

5th gear was only about 1/4 the pressure at WOT as 1st gear was at half throttle. So it is not disabled as I read, just greatly reduced. I'll get a baseline for 1st gear WOT soon and I'll see what it spikes to when there is slip for comparison. I wish I could log this stuff!

Interesting that you can directly read the pressure to the multi-plate clutch with FreeSSM. That's downstream of the solenoid and the transfer valve, so it's even more "real", and not a proxy, as in the case of duty cycle. Presumably that's unique to the 5-speed.

The relatively low pressure readings aren't surprising. The 5-speed has a mechanical (planetary gear) differential that drives the front and rear systems full-time. The clutch isn't needed when all four wheels have good traction and the signals from the front and rear VSSs aren't significantly different. The clutch would be used primarily when slip is detected, i.e. when the signals differ, and only enough to bring the two signals back into sync,, or when the risk of slip is high, such as at WOT in low gear.

In the 4EAT (and CVT) the clutch is the only method of power transfer to the rear and therefore has to be active to a greater degree all the time. But again, VSS signal differences would have a proportionally greater influence on the duty cycle, perhaps more than throttle position at least until wheel slip appears.

I don't think there's a "safe" and simple way to test for pressure or duty cycle when there's loss of traction. Perhaps a two axle dynamometer where the rear rollers can be loaded (braked) might can be used to simulate front slip. Another might be to disconnect the front axles so that the front drive is free wheeling. This would probably lead to maximized duty cycle/pressure, but could place unusual strain on the clutch.

This is a quantum leap in the AT knowledge base. My continuing thanks to you and ntippet for the work you're doing.

 

[plain OM]

The link you posted to the cable is the exact one I bought.

Thanks again! It's now ordered, and I've downloaded the program but can't go anywhere with it until the cable is in. (Might be a couple of weeks for the cross-border regular mail system.)

Incidentally, I understand "slip" detection is based on the VSSs and not individual wheel speed. (This applies to AWD control, not VDC which is based on wheel speed.) As such, the AWD control system only ensures that the front pinion drive shaft (to the front differential) and the rear propeller shaft (to the rear differential) are turning at the same speed. This leads to actual situations that appear contrary to the perceived AWD concept. The ideal is that both shafts are turning at the same speed and all wheels are doing the same. But it's quite possible for 1) one rear wheel and one front wheel to be spinning (in the absence of a limited slip rear differential); 2) one rear wheel and both front wheels to be spinning; or, 3) both rears and one front wheel spinning, all with the shafts turning at the same speed, leading to no perceived "wheel spin" and therefore no AWD clutch action.

This will make test readings problematic in a real world situation (e.g. in snow) because it would be difficult to monitor/control what each wheel is doing.

 

[Seabass]

I'm just going to accelerate hard from a stop in the rain with the wheel turned. That should result in enough wheel spin in just the front wheels to lock up the clutch. Probably in a parking lot. Freessm will remember the max value, so I don't have to watch it for this one.

I'm not sure how it calculates pressure. But it does the same thing for several of the solenoids. I think it is just the amount of pressure that the tcu is requesting.

 

[Seabass]

BTW, since you are getting a vag-com cable anyway, check out the experimental ecu definitions in romraider. There may be something useful working. I know there are some things defined for the 05 legacy 2.5i.

 

[ntippet]

Incidentally, I understand "slip" detection is based on the VSSs and not individual wheel speed. (This applies to AWD control, not VDC which is based on wheel speed.)

Good to know!
Mine is LSD in the rear but I can see the fronts distributing unevenly.
I will have to do some fun playing around in the snow with these craptacular all weather tires for the slip testing.
Should be easy to get differing F/R wheel speeds, but we will see.
Have to delay putting on the snow tires for a bit.

Donuts in a parking lot sounds fun.

 

[plain OM]

Freessm will remember the max value, so I don't have to watch it for this one.. . . I'm not sure how it calculates pressure. But it does the same thing for several of the solenoids.

Max value hold-- and pressure readings. So where are these on the FreeSSM display? [Edit: Max and Min are clear in ntippet's screen shots -- should have looked back . . ] I can't run FreeSSM yet and didn't find anything that is accessible now that explains all the possibilities.

As was the case with FreeSSM until this thread brought it front and center, I'm not familiar with romraider. I understood it to be more oriented to engine tuning, which at this stage isn't my focus. I'm more interested in getting a good grounding in how things work. But I'll have another look at the website.

This is getting even more interesting.

 

[Seabass]

Unfortunately, you can't view anything until it connects to the ecu or tcu.

Romraider now has some tcu logging capability. I haven't had a chance to play with it yet. It is tuning oriented, but there is tons of information to be had from playing with it. It's the logger that I think you'll be interested in. Not the ecu editing part.

 

[plain OM]

Seabass:

Re: romraider


I looked at the website, my eyes are getting tired and I'm getting confused, and I have questions.

[This feels like sitting down and eating a McDonalds hamburger in a Burger King, but the discussion of FreeSSM and romraider are in keeping with the topic -- access to the ECM and TCU data.]

Will the cable I've ordered work with romraider, or is the Tactrix cable required? (Didn't see anything other than the Tactrix mentioned.)

My interest is, indeed, only in logging and graphing/charting/storing real time data from the "standard" SSM parameters that the dealers have on the SSMIII. I'm definitely not into altering the tuning (ROM). I understand both the separately downloadable ECU/tuning definitions and the logging definitions are required for romraider to work, but is this for tuning or for logging as well? In other words, if I download only the logging definitions, will that meet my intended use or do I have to also download the ECU/tuning defs?

In this regard, do I have to download any separate defs? It appears that the basic romraider program download does not come with either the standard or enhanced definitions, but I'm not certain of this. Is this correct? Or does the basic program have the standard parameters and the extra downloads are needed only to access the "enhanced" lists of parameters?

 

[Seabass]

You would need to download the experimental ecu definitions as well as the logger definitions. This is so romraider will recognize your ecu.

As for the tactrix, I don't know enough about your ecu to know whether the vag-com will be compatible or not. Do you know if your ecu is can-bus? I know subaru made a switch to can-bus ecu's, but I'm not sure if it was in 07 or 08 or whether the n/a ecus switched. If it is not can-bus, then you should be able to use the vag-com cable. You will also need to set up the drivers for the vag-com cable for romraider.

 

[plain OM]

You would need to download the experimental ecu definitions as well as the logger definitions. This is so romraider will recognize your ecu.

Thanks.

Since my last post I found that it appears the ECU list doesn't include the 2007 2.5 n/a with AT (only MT), at least not that I could see, so I guess this is all on hold for the time being. Too bad, the recording/graphing would have been interesting.

Back to FreeSSM . . .

 

[plain OM]

. . . . As for the tactrix, I don't know enough about your ecu to know whether the vag-com will be compatible or not. Do you know if your ecu is can-bus? I know subaru made a switch to can-bus ecu's, but I'm not sure if it was in 07 or 08 or whether the n/a ecus switched. If it is not can-bus, then you should be able to use the vag-com cable. You will also need to set up the drivers for the vag-com cable for romraider.

If it is CAN, which I believe is the case according to the FSM, then if the vag-com won't work with romraider and the ECU, is it going to work with FreeSSM?

. . . I know it works at least up to 2008, but beyond that I do not know. . . . ..

Was this verified with the vag-com cable?

If I've headed down the wrong road with the vag-com, I'd rather order another cable now that will be suitable for FreeSSM and my 07, rather than wait a couple of weeks for the vag-com cable to arrive and find it doesn't work.

 

[Seabass]

I think it will work. My understanding is that it will only work with freessm. It needs the ssm protocol to be able to access the ecu. Romraider doesn't use ssm as far as I know.

 

[ntippet]

Way to jack up the thread with romraider!
Haha
No its a good place for it, lands in the same category, fine by me.

CANbus Models
http://www.obddiagnostics.com/CAN_List.pdf
Crap you're right, it might not work with canbus.

From the help_en.html file contained in the installation directory:

"2.) Which vehicle models are supported ?
The software supports the models Legacy®/Liberty®/Outback®/Baja®, Impreza® (incl. WRX + STi), Forester®, Exiga® and Tribeca® starting with model year 1999 up to model year 2009.
Model year 2010 is already supported, too, but some Measuring Blocks may be missing and some Diagnostic Codes may not be displayed as plaintext.
Vehicles up to model year 1998 as well as the models SVX®, Justy®, Libero® and Vivio® are not supported.
The model years 1999+2000 must be regarded as transition period. According to present obersvations (european models), access to the engine control unit of the models Legacy®/Liberty®/Outback®/Baja® is already possible since model year 1999, while most of the Impreza®-models and a few of the Foresters® are supported from model year 2000 on.
Transmission control units are not supported before model year 2000, in most cases support starts with model year 2001.
It is useful to take a look at the diagnostic connector: if pin 7 is available, at least the engine control unit should be available.
From model year 2001 on, both control units should be supported."

"14.) Does FreeSSM use/support the CAN-Bus ?
No, because it's not necessary. Of course, the newer vehicles are working with a CAN-Bus system, but it is not used for diagnostic purposes at manufacturer level or rather the communication between engine/transmission control unit and the diagnostic equipment."

Might be worth exploring the RomRaider path instead.
Scoobypedia | Trusted knowledge for everything Subaru | Knowledge / Rom Raider and Reflashing FAQ

Although the cost of the Vag-com cable is hardly anything compared to the Tatrix one...

 

[Seabass]

According to the freessm developers, the vag-com should work for all supported models. Freessm doesn't need to use can-bus since it connects through the ssm protocol. It should work fine.

 

[plain OM]

Romraider doesn't use ssm as far as I know.

Apparently it does. Under Subaru Logging:

"RomRaider uses the Subaru Select Monitor (SSM) protocol for logging which is faster and has more capability than standard OBD-II logging."

It's use is also mentioned eight other times in the Rom Raider FAQ.

Crap you're right, it might not work with canbus.

Maybe not. As Seabass notes, FreeSSM doesn't use the CAN, and this seems to be confirmed by the answer to question #14. If the CAN doesn't introduce any changes to the OBD connection as far as diagnostics is concerned, then FreeSSM should be fine. If I understand this, the diagnostics in the cars with CAN are the same as they were in the ones without CAN, and therefore, if the vag-com cable and FreeSSM worked for the latter it should work for the former. Also, the help_en file, which I finally read through, refers to the vag-com KKL adapter (as did ntippet in post #1) and there's no mention of it not working with FreeSSM on cars that use CAN. I feel a lot more confident now, and will just wait for the cable to arrive.

EDIT: p.s. http://www.romraider.com/forum/viewtopic.php?f=7&t=6206 addresses the issue of using the vag-com with Rom Raider in the seventh post. Looks like it will work up to 2006, but not beyond (CAN).

 

[ntippet]

Glad that's settled then.

 

[Seabass]

Have you measured what the transfer solenoid is doing in a steady low throttle input conditions (cruising)? Frankster on legacygt.com had a 2002 4eat on his lift. He said during acceleration, all 4 turned, then under steady throttle, the rear wheels stopped while the front kept going. I'm curious if it completely cuts off in certain situations.

 

[ntippet]

Have you measured what the transfer solenoid is doing in a steady low throttle input conditions (cruising)? Frankster on legacygt.com had a 2002 4eat on his lift. He said during acceleration, all 4 turned, then under steady throttle, the rear wheels stopped while the front kept going. I'm curious if it completely cuts off in certain situations.

Yes I posted that information on page 4.

From what I have seen it never cuts below 35%.
You would have to use the FWD fuse to do that.

 

[plain OM]

In http://www.subaruoutback.org/forums...-complete-access-your-ecm-tcu.html#post367598, even when decelerating (as well as cruising) the duty cycle appears to remain significant.

As far as I can recall of threads I've read, with the car raised both front and rear drives were functioning (turning) when in gear, even at idle.

What is strange in that case is the rear VSS signal would have been at or close to zero, and the difference to the front VSS signal, one might think, should have triggered an increase in clutch activation (in the 2002, a reduction in the duty cycle).

Was there any further discussion in that thread about the rear wheels not turning? (Link)