ETM Symptoms

[Brendonham]

After reading on this site and others I am concerned that my '01 XC may be experienceing the onset of ETM failure. On the highway this week, 35 degrees with rain, I was feeling some slight hesitation & surging. At first I thought maybe I had a little water in the tank but when I read about the ETM problems and have learned about the warranty extension I'm wondering if this is what's going on. Does this sound like an ETM problem? The car is going into the dealer tomorrow morning so I want to make sure I don't get shuffled out the door without fixing the problem.
Thanks to everyone who's been so diligent on this issue.
Brendon

[howardc64]

I think everyone that had ETM problems also got a "Performance Reduced" message. Did you get this?

It could be the ETM issue everyone is talking about. Dealing with the ETM like symptoms myself. I haven't found any way to confirm ETM problem without visiting the dealer. In other words, no DIY diagnostic procedure to be shared on this DIY board :-( Someone who had the ETM replaced gave me the following diagnostic codes read by the dealer.

ECM-130A Air leakage intake
ECM-903F Throttle unit, internal fault - signal missing

I don't know if these codes can be pulled by OBDII scanner or if VADIS would be necessary.

I'm also wondering how well dealer's diags can pin point ETM because I also see in these boards people replacing gas pedal switch + maybe MAF at the same time as ETM in some cases. I doubt all these things go at the same time. It may point to inability to pin point via diagnostics.

You can see how they all may cause throttle problems, when the throttle is not behaving correctly. Is the problem from sensors in throttle position? foot pedal? or amount of air intake?

But certainly the most common problem is ETM. If they ask you to replace the other 2, you should probably ask them to give good explanation and maybe do it in 2 stages (ETM first, the others later) to makes sure you are not paying for things that don't need replacing.

Sorry but I've not found a consistent and clear diag sequence yet. This is probably best I can arm you with before going to the dealer.

[Brendonham]

Thanks for the insight. You're right though it does seem that most folks have had the car alert them of the problem after a loss of power or high idle rev. After taking the car into the Dealer they said there were no codes so everything is A-Ok. Well I'm still feeling the fluctuation in the engine. It's really not in the pedal and I don't see the revs doing anything, it's kind of a slight dropout as I'm driving at highway speed. I guess it's just a matter of time. Thanks again for your thorough response.

[howardc64]

When I describe my hesitation symptoms as like driving in a windy day. Others with replaced ETMs said that is exactly what they felt during the early stages prior to getting limp home mode.

I think you probably won't feel anything (with your foot) if the foot pedal sensor went bad. It would just send the wrong position values (load request) to the ECU. But ETM is the more likely culprit based on everyone's experience.

My car also sometimes exhibit sluggish power symptom without error codes. I've got a recording of key sensor values (timing advance, throttle position, MAF, intake air temperature ....) through a PC based ODBII scan tool when the engine is powerful. I'm trying compare these sensor readings when the engine is sluggish.

I've also found out that ECU reset (through some lengthy period of power disconnect) erases whatever setting is causing the sluggishness. I'm guessing this maybe why people felt more power after ETM cleaning. It is more likely due to ECU reset if battery was disconnected extensive amount of time.

This is indeed a complex set of symptoms to diagnose. Clearly, something is wrong with your car but the dealers diagnostics can't find it.

[howardc64]

Finally got "Performance Reduced" to occur on back to back driving cycles. This stored a code + lite up the CEL. I also got a message like "Engine Service Urgent".

OBDII shows the code to be 1603 which translate to Volvo DTC ECM91A7 (ETM internal failure).

The local Volvo dealer read this code and replaced the ETM for free (Thanks Don). Everything is back to normal now. Dealer also read another code which didn't show up on my OBDII reading (904D = pedal sensor fault). They didn't suggest to replace the pedal position sensor. I definitely wouldn't have done it if they suggested replacement because the computer might have misdiagnosed this due to ETM problems.

So the short summary of my DIY ETM diagnose is

** have an OBDII reader when "Performance Reduced" message shows up to get the code. Translate it using

http://www.volvoxc.com/resources/how-to/pdf/p_codes_conversion_table_standardized_dtcs.pdf

** hope you get one back to back driving cycle so a code is stored.

I didn't try this but if you are having a hard time to get back to back "Performance Reduced" messages. Perhaps you can go to the dealer on the very next driving cycle after a driving cycle which produced a "Performance Reduced" message. Before shutting off the engine (end of the second driving cycle for the ECM, if the same problem doesn't occur, the pending code is erased), have them read out the ETM internal fault pending code seems like a reasonable way to show the failure.

Disclaimer: I don't really know if there situations where OBDII reader get no code and Volvo's VADIS can retrieve a code showing ETM problems. I didn't try this path (I've heard $80 charge just to check if there are any failure codes)

Volvo dealer was very nice and replaced it promptly in 2+ hours. NHTSA complaint filed. Don got us the first 2Rs. Looking to get the remaining 2Rs.

[starfish]

I think everyone that had ETM problems also got a "Performance Reduced" message. Did you get this?

Someone who had the ETM replaced gave me the following diagnostic codes read by the dealer.

ECM-130A Air leakage intake
ECM-903F Throttle unit, internal fault - signal missing

ISorry but I've not found a consistent and clear diag sequence yet. This is probably best I can arm you with before going to the dealer.

Those codes are most likely caused by a clogged or restricted breather system. Poor quality engine oil and extended oil change intervals can cause engine oil sludging and create this fault code. Negative 0.2 kPa or lower read out with a manometer on the engine oil dipstick tube with the engine idling, A/C & all other accessories off is the specification.

Edit: The cause has been known to many techs for a long time, but the specification and testing manner are new.