The Xemodex

fast850 · Post by **fast850** » 25 May 2010, 18:48

I pulled my OEM 01 V70's apart and this is what I found

http://volvoforums.com/forum/showthread ... ght=xmodex

Electrical/Electronics Engineer and very skeptical of their solution (except for the very early models, as stated)

How do you interface a digital angle indicator with a sealed firmware embedded system of silicone die construction. You might do it with this(but still a big challange)

http://www.nxp.com/documents/data_sheet/KMA200.pdf

you still have to get power to the IC/board, find a location in the cramped space and this is not the issue anyway, it's the servo and servo driver and its inability to drive the servo rotor when the throttle plate/shaft gets gummed up. Please do yourself a favor and read the thread on Volvoforums.com.

ChrisatXeMODeX · Post by **ChrisatXeMODeX** » 26 May 2010, 08:32

Mr.fast850/bobec,

"Don't buy the XeMODeX until you are sure it is the ETM " -should be your heading.

It has been very well documented that the proper ETM cleaning will extend the life of the throttle module, it will also help to stabilize the idle etc. This is nothing new, however this is TEMPORARY solution and effected Volvo owners should not be mislead that this is a magic fix.
It is also known that problems with charging systems, MAF failures, fuel pressure etc. will exhibit similar symptoms or effect ETM performance directly.
Don Wilson has extensively covered the actual ETM failure on his site years ago, his findings has spark the extended ETM warranty in North America.
Indeed in your particular case the potentiometers might not be worn all the way and cleaning will help, but sooner or later they will wear off.
How do you know when your potentiometers are worn? Simple... Take your car to the Volvo specialist and ask him to preform ETM "Potentiometer Sweep Test" on his VIDA. If your throttle passes the test then your potentiometers are fine and cleaning the throttle might help. If it fails, then replace the ETM unit.

I'm not exactly sure why are you hijacking all the treads with links to the other site?
Are you trying to make fellow owners aware of you magic fixes (cleaning or replacing the battery)? Or that you are on the mission because we refused to supply you with our contact-less potentiometers?

fast850 · Post by **fast850** » 26 May 2010, 19:26

Do you really know the failure mode of the ETM? Tell me just how the Volvo Tech is suppose to do the pot sweep with VIDA. I'm pretty sure vida can't look at pot readings in real time, the ETM MCU(micro control unit) does that . Do you even know the communication interface between the ECU and the ETM? Please tell all of us how you power the digital angle indicator, mount it on a board and transform digital data to analog before sending it to the ETM, because the ETM is looking for a voltage divided ADC input, period. Do you even know what an ADC is?

Everyone....Clean...very well your ETM, lubricate the shaft with thin synthetic oil, then replace your battery and see what happens. Please let me and others know. Don't think that Snake oil and mass panic is the answer.

I have never and will never ask for your snake oil remedy because its thin air. It's shear BS. Me and many others have 14 year old 850 with one full contact pot. TPS and they are still working just fine so don't blame it on the TPS. It's an over loaded servo/servo driver because the ETM gets dirty and the motor can' turn it. And people who don't clean it right accomplish nothing.

Post by **polskamafia mjl** » 26 May 2010, 19:32

I'm an Industrial Engineering student not an Electrical Engineer. However, I am really interested in the conversation going on here. Could you explain your theory once again without using the electrical terms and acronyms?

Post by **mvsuzr** » 26 May 2010, 20:09

Contactless positon indication is an established technology, it's used in some heavy industrial applications where film pots can't stand up to environment.

If it rubs, it will wear out.

In the end, if the Xemodex unit out performs the stock ETM, does it really matter what technology it uses?

fast850 · Post by **fast850** » 27 May 2010, 07:02

polskamafia mjl wrote:I'm an Industrial Engineering student not an Electrical Engineer. However, I am really interested in the conversation going on here. Could you explain your theory once again without using the electrical terms and acronyms?

First there are some pics I took here that show the internals of the Magneti arelli ETM http://volvoforums.com/forum/album.php?albumid=632

IMO it is a pretty well engineered and constructed module. It has two (not just one) potentiometers (see pot surface and wiper fingers pics) that send a micro controller (shown in the pic titled "silcon die") a dc voltage that is converted to a digital value using an analog to digital converter (ADC) so the control system knows the position of the throttle. They are sealed in very small compartments in the ends of the ETM with o-rings and potting compound. The multitude of fingers on the wipers are delicate and they float on the shaft so they do not wear the resistive tape that they make contact with. I'm not sure but I have an idea that is the firmware losses an input from one of these then a code would be sent to the ECU (engine control unit) and you'd get a CEL (check engine light)

Yes, hall effect no-contact sensors might (more on this below) be better and I initially thought that Xemodex had a great solution until I took my ETM apart and saw how difficult/impossible it would be to implement. Hall effect sensors (see data sheet link in above post for more info) are active devices that sense the orientation of a magnet field, (they need clean, locally filtered DC power) they need to be mounted on a printed circuit board, and in most cases their output signal has to be processed to meet the input criteria of the MCU.

The wipers and contact surface of my ETM were in excellent condition considering the car has 110K on it. I did a few sweep tests on the bench before I even cleaned the tape surface and both were perfect. So this gets me thinking an researching. If we have two TPS and one fails the other should allow us time to get the car fixed and we won't be breaking down all of the sudden on the side of the road or at best get to limp home. While looking closely at the servo motor I'm impressed by how wide the air gap is between the rotor (the part that turns with the the throttle plate) and the stator coil ( the coils that generate the magnetic field that turns the rotor). This air gap(not that this is a design flaw) decreases the magnetic field strength that works to turn the rotor. So this make me think if the throttle plate and shaft get dirty, contributing to the torque required by the servo to turn it then the throttle will not respond to the servo driver's input and the car is on the side of the road. Single point of failure. So if the servo is sensitive to friction caused by dirt, it will most likely be sensitive to low DC supply voltage. There was a guy on Volvo forums who had replaced his ETM with an Xemodex and still had to get his car towed to his mechanic, they couldn't figure it out until I suggested he replace the battery. Car ran perfectly.

More on the hall effect sensor... If the hall effect sensor is mounted on the servo motor end of the ETM there is a problem. The servo motor generates a magnetic field in order to turn the throttle plate but the hall effect sensor is a magnetic field sensitive device so reason would have it that as the magnetic field of the servo changes in strength as it is commanded to turn the throttle plate it has a affect on the hall effect sensor.

Post by **polskamafia mjl** » 27 May 2010, 07:11

Ok, I think I understand a lot more now. But most importantly I can see that we may now have 2 viable solutions for the ETM problem. If you can find a conclusive test to prove your theory and it works then this could help out many later generation Volvo owners. I don't know what you would have to do to prove/disprove your theory but I think more people need to be paying attention to this thread.

Edit: I don't want my comments to be mistaken as me taking sides. I just want all methods of fixing a problem to have a chance at being tested and noticed by the people who suffer from that problem.

ChrisatXeMODeX · Post by **ChrisatXeMODeX** » 27 May 2010, 07:20

Do you really know the failure mode of the ETM? Tell me just how the Volvo Tech is suppose to do the pot sweep with VIDA. I'm pretty sure vida can't look at pot readings in real time, the ETM MCU(micro control unit) does that . Do you even know the communication interface between the ECU and the ETM?

Providing that the Campaign 155 (ETM Software Upgrade) has been preformed any ETM unit can be sweep tested. This function is built in right in to VIDA and must be preformed before the unit is replaced under extended warranty.
Once the vehicle is hooked up to VIDA and pot sweep test function selected, the ETM will activate in a special mode. Throttle plate will be activated from fully closed and advance in small incrementation to fully open several times. At the same time graph screen will show the actual readings from both potentiometers. Maximum allowable difference between the two pots is 13 degrees, once its exceeded ETM must be replaced. FYI Maximum difference allowed on our pots is 1 degree, this is why our throttles are more responsive.

Please tell all of us how you power the digital angle indicator, mount it on a board and transform digital data to analog before sending it to the ETM, because the ETM is looking for a voltage divided ADC input, period. Do you even know what an ADC is?

XeMODeX DAS is a self-contained unit, once old pots are removed DAS is connected directly to the existing terminals. No secondary power supply is needed from the board. How exactly DAS operates is a trade secret.

To summarize; ETM pots can be tested, if the unit fails the test cleaning the throttle is pointless and is a total waste of time.

ChrisatXeMODeX · Post by **ChrisatXeMODeX** » 27 May 2010, 07:52

The nature of the ETM failure has been researched and covered extensively by Don Wilson home.comcast.net/~donwillson/

Moderator; Please edit the heading of this thread as it sends the wrong message. Title of this thread is totally irrelevant to the topic being discussed.

fast850 · Post by **fast850** » 27 May 2010, 10:46

XeMODeX wrote: FYI Maximum difference allowed on our pots is 1 degree, this is why our throttles are more responsive.

There it is you said it, and I do believe yours are more responsive than a 9 year old unserviced and "not" ultrasonically cleaned one. Aluminum oxidizes over years of being exposed to the harsh environment of an intake manifold and this along with the dirt buildup ? Quick response is a direct function of the servo driving circuit and servo motor's ability to react to the process input/error. The Pots are feed back devices used to verify the movement and validate functionality.

polskamafia mjl wrote: If you can find a conclusive test to prove your theory and it works then this could help out many later generation Volvo owners. I don't know what you would have to do to prove/disprove your theory but I think more people need to be paying attention to this thread.

Edit: I don't want my comments to be mistaken as me taking sides. I just want all methods of fixing a problem to have a chance at being tested and noticed by the people who suffer from that problem.

I don't have the time and really nothing to prove. These are my opinions only. However, I think people might consider trying to clean "very well" the throat, plate and more importantly around the shaft and then lubricate the throttle shaft (I used a Qtip soaked in synthetic oil to apply around the shaft) before they take a more costly approach. And also replace their battery if it's older than 3 years. If there is enough success with this approach then it will be proof enough. The only problem with this approach is clean means different things to different people.