Volvo S70 ETM failure, or MAF sensor?

dolfelt · Post by **dolfelt** » 07 Aug 2012, 20:37

This is my first post, so excuse me if I sound new at this. I am trying to determine what exactly has failed on my car. While I was out driving the car stalled, I could get it started again, but it would just rev up and down in idle, almost rhythmically, then when I would give it gas the RPMs would drop, and the car would perhaps stall. In the end I had to get it towed (to my driveway).

I was originally thinking it could be the throttle body (perhaps needing cleaning or replacement), but I tried unplugging the MAF and starting the car again. The reving up and down is gone. However, when I give it gas it sputters a little and then idles rough for a couple seconds before idling just fine again. The Check Engine light is on, as is the ETS.

So my question is, would it be worth replacing the MAF? Or is this problem still most likely related to the ETM? Thanks!

Post by **JimBee** » 07 Aug 2012, 21:29

Here's how you can test the MAF:
http://easyautodiagnostics.com/testing_ ... ting_1.php

If you click to the next pages, you'll see a link for the Volvo.

Basically, you do three things:

1. make sure you don't have vacuum leaks, as they can let unmetered air into the engine, which will give you the wrong mix of air and fuel. It's the job of the MAF to meter all air coming into the engine then pass that info along to the computer so it knows exactly how much fuel to inject into the cylinders. Check the vac. lines, including the one elbow under the intake manifold near the power steering pump.

2. pull your MAF unit and give it a good spray cleaning with MAF cleaner. Don't touch the element with anything.

3. Then test the MAF, electrically as the tutorial at the above link. At pin 4 on the MAF plug, you should have .8 to 1.2 volts dc
at idle. And it should be steady, not jumping around. Then as engine rpms increase, the pin 4 voltage should steadily increase up to around 4.4 volts at 3500 rpm. Five volts is max output. If the MAF is in those ranges and steady, it's working correctly.
The linked tutorial gives more details.

Good luck.

madspeed50 · Post by **madspeed50** » 07 Aug 2012, 23:00

Sounds like classic ETM failure to me

Yep, sent from my rooted, rommed Galaxy Nexus....

MilehighV70XC · Post by **MilehighV70XC** » 07 Aug 2012, 23:58

Next step, find out check engine code. If idle smoothed out with the MAF disconnected, I would check that first using the link posted above. Car will idle with the MAF disconnected but wont rev smoothly. Same symptoms you are experiencing

Post by **MoVolvos** » 08 Aug 2012, 02:40

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Here are two items on ETM cleaning. The cost is labor and may help? A recent post had some kind of idling issue also and the MAF took cared of it.

Gives you an idea on cleaning. The 70 series is similar if not easier according to another recent post.

ETM Cleaning solved this 2000 V70 idle problem
https://www.matthewsvolvosite.com/forums ... =9&t=47459

Blessings,
BKM

dolfelt · Post by **dolfelt** » 08 Aug 2012, 07:56

madspeed50 wrote:Sounds like classic ETM failure to me

That's what I originally thought, but when the idle problems disappeared when I unplugged the MAF sensor, I began to doubt that it was the ETM. Guess I'll do those MAF tests and see. Crossing my fingers that it is the MAF sensor!

dolfelt · Post by **dolfelt** » 08 Aug 2012, 08:08

Another thing I just discovered is that it looks like the ETM has been replaced (before I owned the car in 2009). The ETM that is in the car right now is a Magneti Marelli, which I believe is an aftermarket ETM. Does this ETM suffer from the same design flaws?

Post by **precopster** » 08 Aug 2012, 09:01

Magnetti Marelli was the OEM supplier for throttle bodies Volvo b/w model years '99 and 2002.

Refer this forum: https://www.matthewsvolvosite.com/forums ... m.php?f=12

There is NO alternative other than to use a Magnetti Marelli but there ARE companies such as XeModex rebuilding them for Volvo fans out there with NON-CONTACTING Hall effect sensors.