2007 XC70 - Another Rough Idle - Help!

[pittsjock]

Greetings.

I have an 2007 XC70 that we have owned since new. 125,000 miles on it. Dealer serviced in accordance with factory specs up to about 100,000 miles.

In January of 2012, it started surging a bit at idle. It wasn't really noticeable on the tach, but you could hear it. The Volvo dealership replaced the mass airflow sensor. The problem mostly went away, although it still didn't run quite right. The check engine light would come on if the car got very close to empty, but would cycle off almost as quickly.

The code was mass airflow sensor (I forget the number).

In November of 2012, the problem got worse again up to the point where the car would not start one morning. The Volvo dealership took no responsibility so I fired them and went to a local mechanic that I know. He is not a Volvo expert, but he is pretty good.

He again replaced the mass airflow sensor and the problem went away mostly, only to return in about 6 months. The check engine light would generate the same codes.

In May, we went for mass airflow sensor number 3. It lasted less than 6 weeks before the problem resurfaced. In the meantime, my local mechanic hired a new guy who owns a Volvo and had a pretty good understanding of the system.

Between their searching and mine, we looked at a whole bunch of other things, but the only thing that came up was too much fuel pressure. They replaced the fuel pressure sensor, put in a replacement mass airflow sensor and the car ran great for one day.

Back to rough idle. It runs great for a while when stopped and then stutters. It usually does not shut down, but stumbles and then smooths out. I would say it runs reasonably well at speed, although it is not quite right. Just a bit of vibration like things are quite tuned up correctly.

I am not a big fan of just replacing parts. We haven't checked the latest codes, but sure seems like it will pull another mass airflow sensor.

I saw the posts about throttle body cleaning. Is this next?

This is our second XC70 - the first was a 2004 and it was a gem. This one has been just OK with a whole bunch of little problems. I would like to get another 30 - 40K out of this car, but not if it isn't going to be reliable.

Thanks in advance for the help.

Patrick

[pittsjock]

I realize that I had started a thread a while back and completely missed the responses. This one has a bit more information. I see several folks suggesting that we replace the spark plugs. I am going to take a look at them tomorrow.

[pittsjock]

Sorry I missed the other thread.....there is great advice there. I am not a "hit and run" kind of a guy.

The VVT solenoid looks like another potential culprit. I am going to check resistance tomorrow and see if I can find anything there.

Is there any other code related indication of a bad VVT solenoid?

I also updated my subscriptions so I see when people respond.

Thanks again for the help.

[howardc64]

Tough problems with no codes. Does your mechanic own Volvo's diag tool VIDA/DiCE? Since your car is acting up frequently, might want to look at some engine parameters live while the problems are occurring to see what the engine "sees".

I chased a MAF problems a few years back on a 01 V70 T5. No codes! I finally swapped the MAF with my other 01 Volvo (V70XC) and isolated to MAF. But a second Volvo is an expensive diag tool

It is interesting MAF keep on going bad. I recently read clogged PCVs ruins MAFs on these Volvos (google "volvo clogged PCV MAF"). Has the car's PCV been done at 125k miles? If not, chances are its clogged somewhere.

[pittsjock]

Thank you Howard. No cleaning on the PCV......so I may have a Sunday full of PCV cleaning......found the instructions. Thanks again.

[JRL]

Clean that throttle.
I just sold an R with 83K and it ran goofy. Cleaned the throttle and did some Breather work (no new plugs) and it runs GREAT

[howardc64]

Don't know if PCV will fix your problem. Might do the latex glove over the oil filler hole test to see if the idle circuit is plugged. But having a healthy PCV is definitely a good idea anyway. Per JRL, clean the throttle, it will be right there when you pull the intake manifold off.

[pittsjock]

Gents: Thank you again for the suggestions.

I just removed the oil filler cap and used a latex glove. I didn't see or feel any vacuum. I think it has slight positive pressure because when I quit stretching the glove across the opening, I could see vapor coming out - not enough to blow up the glove, but enough to let vapors/condensation out.

I think I am going to try and clean the PCV system. Looks like a whole bunch of fun.

Thanks again for the help.

[Astro14]

Cleaning the throttle body will make a big difference in idle quality and off idle response.

If you're doing the PCV system, the intake manifold has to come off, so the throttle body (ETM) has to come off, a soft brush and can of cleaner are all you need for the ETM. For the PCV, I would recommend getting the kit and replacing the parts. Trying to clean them usually results in broken plastic bits that have to be replaced, and a car that is not running while you go get the parts at the dealer for twice what you would have paid for a kit from either IPD or FCP.

[pittsjock]

Cleaning the throttle body will make a big difference in idle quality and off idle response.

If you're doing the PCV system, the intake manifold has to come off, so the throttle body (ETM) has to come off, a soft brush and can of cleaner are all you need for the ETM. For the PCV, I would recommend getting the kit and replacing the parts. Trying to clean them usually results in broken plastic bits that have to be replaced, and a car that is not running while you go get the parts at the dealer for twice what you would have paid for a kit from either IPD or FCP.

Got it. So this is a $400 investment in parts and a bunch of time - clean throttle body, replace PCV system and hopefully she'll purr like a kitten.

Thank you.

Patrick