2006 5-cylinder XC90 sputters when accelerating hard

[Nebulous]

My wife's 2006 XC90, 5 cylinder, sputters/vibrates when driving at highway speed and the gas pedal is pressed hard for rapid acceleration. I'm not sure how clear that is, so I'll try to explain better.

I first noticed it when driving on an Interstate in the hills of West Virginia. We were going about 70 MPH but were about to climb a little bit of a hill and so I pressed the gas pedal suddenly so as to maintain my speed. I felt the car vibrate underneath in a way that is difficult to exactly describe. It felt like a very momentary minor decrease in speed - sort of a brief stall - and then almost like a few brief spark plug misfires in a row, then it accelerated just fine. All of that was within 2 or 3 seconds, tops.

[NOTE: We just recently bought the car and this was the first time driving in these condition].

After encountering it the first time, I experimented and realized I could make it happen consistently simply but pressing the gas pedal fairly hard when driving at highway speed. Going up hill wasn't necessary.

It doesn't seem to happen, at least not as easily, when driving slowly (such as in town) and punching the gas.

By necessity, we've driven a few thousand miles on it like this. It doesn't seem to be doing any damage, but who knows?

I do not work on cars other than very minor things, but I have friends who are talented and do help. I am just hoping to get from you experts some suggestions of what may be causing the problem that I can pass on to them. Maybe someone will even recognize this as a common problem with this make or model and suggest the fix.

Thank you!

~N

[oragex]

Maybe one of the ignition coils. These are durable (unlike most other cars) but sometimes one goes bad. No need to replace all of them, just find the culprit (can get a used one off Ebay and replace them one by one). By all means don't replace them with an aftermarket ignition coil, only Volvo for this part.

[RickHaleParker]

It sounds like it is having problems downshifting or something going on with the torque converter lockup. Because you don't know the vehicle's history ... I would start with a transmission filter and fluid change.

[Roger_850T]

Did you get any check engine light at all?

I'd look around for any hole or tear in any of the induction piping (rubber air hoses). It might be that as the turbo spools up, it starts blowing air out a hole, and since that would be after the air mass meter, you would lose air but get the fuel for that air, and the car would go rich.

Other things you could do - if you have VIDA and a DiCE, you could log a few parameters and watch it happen, and see if you can gain any insights.

Roger

[Nebulous]

Thank you all for your comments. Unfortunately, the forum didn't email me that there were replies.

Remember, I'm no mechanic, so I'm asking the following follow-up questions strictly for my own education as well as to intelligently talk people I know who do know vehicles better than I.

@oragex - I'm curious how ignition coils could potentially affect sudden, or hard, acceleration?

@RickHaleParker - I had a complete tranny fluch done just abiut 2 months ago. I had thought that it might be trouble up-shifting since it happens during sudden acceleration. Am I thinking backward?

@ Roger_850T - Loss of air sounds possible. I don't know what a VIDA or DICE is, but I get the general sense that they are diagnostic computers. Is there anything unique to Volvo here, or would the free computer diagnostic at my local AutoZone be worthwhile?.

Thanks!

~N

[RickHaleParker]

The free AutoZone diagnostic scan might tell something useful. If there are car freaks among your friend, that do their own repairs, there a good chance they have a scanner that can do the engine and transmission. If you get any codes from any scan, post the codes here.