2000 S70 ETM/MAF diagnostics

Caberguy · Post by **Caberguy** » 13 Jun 2014, 10:56

I bought my first Volvo last week, a 2000 S70 Base SE normally aspirated with just under 100k miles.

After a couple of days I noticed it surging on me, and started doing some research and discovered the wonderful world of the ETM failure.

My initial symptoms were rough idle, the idle was hunting a little bit (not nearly as bad as I've seen in some videos, more like +/- 25-50 rpm), occasional surging (not running away, just momentary jerkiness), idle would drop to about 700 when I came to a stop and feel rough. No warning lights.

I disconnected the MAF and drove it for a while having read somewhere that that would help isolate the ETM. The symptoms seemed largely unchanged, but I didn't leave it off for very long. This set off the check engine light, which has since reset itself.

A couple days ago took off the ETM and cleaned it, it's the original white labeled unit. It was quite fouled on the engine side. After cleaning the idle leveled out and stopped dropping much below 900 at stopping. As of yesterday the idle was steady at 900, the needle would bounce a bit, but never really leave the 900 mark. Occasionally the revs would drop to maybe 850-875 when stopping. Took it to the parts shop and had the codes read... nothing, no codes. (I'll likely be buying my own code reader soon).

This morning I took it apart again, found a bit of gunk on the intake side of the throat, and right under the butterfly... I may have just missed this when I cleaned it, though I thought I was more thorough than that. Having put new batteries in my multimeter I was able to do some more diagnostics:
Battery voltage when I parked it last night: 12.6
Battery voltage this morning (about 16 hours): 11.76
Voltage between pins 5 & 6: 11.68 (double checked)
Voltage between pin 5 and positive terminal: 11.76
Pulled fuse #2, when I replaced it the ETM clicked on, whined for about 6 secs, and clicked off.

Should my battery have dropped that much over night? Would that <.10v drop between battery voltage and voltage at the harness be enough to cause problems?

Does this seem to be pointing to the MAF at the moment, or is it more likely the voltage issue? It seems like the ETM might be okay for the moment... I'd be content to get the XemodeX repair and return service if I thought it would help (I like the car other than these issues, and got a reasonably good deal on it), but I'm not totally convinced that's the problem at the moment. Any thoughts?

P.S. It has the OEM Danseo (sp?) MAF, is there a good way to clean that thing?

Caberguy · Post by **Caberguy** » 13 Jun 2014, 11:55

Additional... I re-read the XemodeX diagnostic flow chart and realized I forgot a couple of things...

I checked the voltage between fuse #2 and the neg terminal... they were identical at 11.8 with the battery having warmed up a bit. Does this mean there's a wiring fault?

I also noticed when pulling the #2 fuse a couple of times that the ETM clicks on, but it's not one clear, solid click, it's like two slightly different clicks, or a click and a half, then it whines for 6 secs, and there's a clear click off. It's certainly not what I would call "clicking on and off repeatedly" as the XemodeX flow chart says. Does that sound normal?

Edit: I realize I ran some of these diagnostics out of the suggested order on the flow chart... I may have just confused myself a bit, though if I follow the chart through it points to the MAF, and the other stuff might just be extraneous information

Post by **abscate** » 14 Jun 2014, 04:21

I would look more for a vacuum leak than a bad ETM at this point. What problem are you trying to solve, the slight surging?

Caberguy · Post by **Caberguy** » 14 Jun 2014, 07:22

Yes, it's the surging that concerns me. When I say it's slight, I don't mean to suggest that it's barely perceptible or anything, just that it's not "taking off." On the highway frequently there will be a few brief surges over the course of a couple of seconds, and then it will seemingly be fine for a bit.

A vacuum leak did occur to me, the hoses all seem pliable and in good condition of visual inspection. The main intake that feeds into the bottom of the air box seems to like to rattle loose where it meets the box. It seems unlikely that that could be the problem... could it be?

Post by **precopster** » 14 Jun 2014, 07:36

With no codes it's pretty pointless to obsess aboit the ETM.

The ETM system diagnostic is very good on Volvos and there will be a code or multiple codes upon failure of this system.

Vacuum leaks are more likely. Thoroughly check all turbo hoses for leaks or splits especially the brittle plastic ones.

Caberguy · Post by **Caberguy** » 15 Jun 2014, 12:55

I got out there yesterday with a propane canister and a hose and nothing came up. I didn't have a whole lot of time to spend on it though. I'm a little wary about trying brake cleaner or carb cleaner. I might try the cigar trick though... what's the best place to hook a hose up to try that?

I seem to be getting an intermittently rough/rougher idle. It seemed rougher yesterday morning than it had for a few days, but last night it seemed comparatively better.

I took another little drive on the highway yesterday (the surges are most noticeable on the highway, though they do happen around town too). I noticed that when the little surges happen the tach doesn't seem to move, so the sensation that the car is surging doesn't seem to be connected to the engine revving higher.

I have a code scanner on the way, should be here Wed, I'll check the codes again then. Do codes always signal a warning light? The reader I ordered (Autel al419) does live data, so hopefully even if there are no codes, I can get a sense of what's happening when it surges.

Caberguy · Post by **Caberguy** » 17 Jun 2014, 17:23

Got my code reader today, pulled three codes P0113 (Intake Air Temperature Sensor 1 Circuit High), P0102 (Mass or Volume Air Flow A Circuit Low) and P1612 (Electronic Control Module Incorrect Coding)... going to do some searching on these... any ideas. (Oops it was actually 4, also P0645 A/C Clutch Relay Control Circuit)

Edit: is it likely that the P0102 is still stored from when I disconnected the MAF, even though the Check Engine light turned off?

Post by **abscate** » 17 Jun 2014, 19:22

Clear codes and drive, monitor codes to see what comes first.

Caberguy · Post by **Caberguy** » 17 Jun 2014, 19:47

Thanks. Yeah, I cleared them, drove for a bit, turned the car off for a while, drove some more. No codes pending or thrown at this point. We'll see.

Interestingly the tach seems to read 900 at idle, but the live data from the code reader had it pegged right about 850. That suggests that the software was never upgraded, right?

Herb Goltz · Post by **Herb Goltz** » 18 Jun 2014, 08:09

I think you should follow up on your battery/charging system. The voltage drop overnight seems high. Have your battery load tested-- Autozone will do it for free. Check your charging system by measuring across the battery terminals with the car running (should be 13.7-14.1V). Also measure the alternator output at the big red wire on the back of the alternator and compare that to the measurements across the terminals (if there is a voltage drop, suspect bad cables).

Good luck!