S-80 2001 Erratic Idle

[wildzontar]

I own a 2001 S-80 that has had erratic idling for years (I can remember as early as 2005). It appears as if the problem is worsening in recent weeks. When idling, I'll notice the tachometer dip below 0.75 RPMs and the lights on the instrument cluster dimming. The engine appears to compensate by sending some kind of brief acceleration that sends it back up to normal (and the lights brighten back up), until it descends once again. Basically, it appears as if the car is going to stall and the engine is going to stop, but never does.

On rare occasions, I'll also notice that the engine appears to accelerate in a short burst as I'm coming to a stop. I have to catch it quickly or else it feels like I will run into the car in front of me.

The Check Engine indicator is on, however the OBD-II code is a seemingly unrelated "EVAP System Large Leak." A few months ago, this was a "Small Leak." A local garage couldn't find any leakage in the emissions system and suggested that I simply reset the indicator periodically.

My father has taken a look at it on more than one occasion and has insisted for years that it is normal behavior, but I am seriously doubting this and am beginning to wonder if leaving this problem unchecked is causing long-term engine damage. At lunch break today, I looked up this erratic idling problem and came up with a possible ETM malfunction, which eventually led me here.

I read that Volvo is reimbursing owners for the cost of a new ETM. My car is basically at the tail end of warranty eligibility, at nine years and 175,000 miles. The car performs otherwise normally in full motion and I have not experienced "limp home mode." Is this a problem I should repair?

[vegasjetskier]

It is not normal operation. My car does not do it, but I have a replacement ETM in mine. If I were you, I'd get it checked out before the extended warranty expires.

[jberdych]

As I understand from other posts, your 2001 S80 has the same ETM as my 2000 V70, and I began experiencing exactly the same "near stall when returning to idle" symptoms you described about 18 months ago. My Volvo dealer (where I have been regularly and faithfully servicing my car for 10 years) recommended an injector cleaning, which only marginally improved the problem.

A year later (that's six months ago) the return-to-idle performance had deteriorated and a new problem arose: the engine would hesitate and then surge, particularly in the 3,000-RPM range just before an upshift. With the cruise control engaged at 60 MPH (2,400 RPM on my manual 5-speed gearbox), the cruise would continuously "hunt" -- the engine would hesitate, then surge, then hesitate, then surge. The Volvo dealer proposed a rather expensive ($285) ETM cleaning, explaining that a build-up of dust and dirt often causes these symptoms. They also acknowledged that the ETM may be faulty, but explained that without cleaning the ETM first, it would not be eligible for warranty replacement.

Here's the part that will interest you: the ETM cleaning completely solved the "near stall when returning to idle" problem. My car drove like the day I bought it ten years ago, returning smoothly to idle every time. So I'm fairly confident that a simple ETM cleaning will solve your problem, and you're good for another 10 years.

Now the bad news. The hesitate-and-surge behaviour remained completely unchanged, and trying to maintain 60 MPH under cruise control or not remained really irritating. So I returned the car to the dealer, asked to have the technician drive for ten minutes to warm up the engine and then try engaging the cruise control at 60 MPH. They assigned a senior tech, he did exactly as I requested, and returned 20 minutes later saying "this car can't cruise worth a shit, we have to change the ETM."

What I found particularly satisfying was that Volvo apparently wants proof in the form of engine diagnostic codes (and my car had none at all) before agreeing to pay for ETM replacement, but my dealer felt that their senior technician's judgement overruled Volvo policy and charged me nothing for the work. Hats off to Volvo Pointe-Claire (if you live in the Montreal area, you really should go there). BTW, my 10-year emissions-related warranty expires in two weeks, and the ETM replacement was just five days ago.

But I strongly suggest that you have your S80's ETM cleaned **at a Volvo dealer**, as it definitely solved my return-to-idle problem very effectively. Watch out for the hesitation-and-surge issues I've described above, and if your Volvo starts exhibiting them before your 10-year warranty expires, head to the dealer pronto. If you've had a recent injector cleaning and ETM cleaning at a Volvo dealer, you should be eligible for ETM replacement under warranty.

[matthew1]

How to clean an S80 ETM <- might be useful to those reading this topic.

[MrJoshua]

I had a similar problem with my 2001 S80, which has 120K, and a new version ETM. The idle was hunting between 7-10 RPM, and then dropping every 2-3 minutes down below 500, causing the engine to shudder, and almost stall. I had a new ETM installed in 2004 after the previous one went into limp home mode, and scared the %#$% out of me.

Recently I took the car into the local Volvo dealership, who tested the ETM, because I thought it was acting up again. I was convinced that the ETM was the root of the problem, but they told me that I needed a Turbo high pressure MOP sensor, to the tune of $400. I figured they knew what they were talking about so I went ahead with their recommendation. What a bad decision. It made no improvement to the idle symptoms.

After some research, I followed the link to the "clean your ETM" section and did some reading. After suffering with the problem for about 8 months, I took the plunge, and tried to clean the ETM myself. It took about an hour to get all of the hoses, sensors and other stuff taken apart. Its not for the faint of heart, but its not impossible either. Just schedule 4 hours to do the job so you don't need to rush. It will be frustrating at some point in the job.

I'm glad to report that after a total work time of 2+ hours, the car is running great, and doesn't stall or hunt at idle any more. I fixed it myself for less than $10 (and the help of the tutorial !)