Greetings,
I am new to this forum. I have a 2006 S60. When I slowly accelerate to 40 mph, the engine shudders for a second, then smooths out. I filled up my gas tank with a higher octane fuel, still shudders. What else would cause this. Plugs? Transmission?

 

do this test - open road - GUN IT - monitor RPMS see where it stutters at. (or under what pressure if you have a boost gauge)

report back

 

Thanks for the reply. I got a couple of messages. One said "Low coolant level...Safely Stop", which I did and added coolant. 30 minutes later, another message says "Transmission Service required". I'm going to mechanic to see about a tune up and transmission flush. I have 45000 miles. Hopefully that's all it needs.

 

hopefully
i do not think the stutter is a transmission issue but i could be wrong.

 

Due to factory defect, radiator cracked and coolant was leaking into transmission, which explained low coolant level and red tint. When tranny was drained, it looked like red milk. Replaced radiator, flushed tranny, and replaced thermostat. Car runs well .....except! The shudder continues as I accelerate to 40 mph. I'm going back to mech and see what he thinks it might be. Funny he didn't mention it when he test drove after completing maintainence.

 

does it matter what gear you are in or what the throttle position is?

 

Yes! It shudders more when I am accelerating uphill, in 2nd gear I think. Between 35 and 40 mph. I have an automatic transmission. Do you think a small vacuum leak could be the cause?

 

thats where i am going with this - vacuum leak or tcv.

That said a shudder (moves the whole cabin and feels like a vibration) is different from a stutter (slight loss of power, momentarily) and impacts the recommendation here.

 

I had a similar issue but my issue turned out to be 2 bad coils, had them replaced and now she runs great.

 

Check your CV joints. Sounds like one of the inner joints is gone. Maybe you cut one of the boots and it ate some dirt.

 

talked to mech. Said it may be one of my trans relays. To drive car for ten days and come back for a check. Still shudders.

 

still havent gotten a clear reading of what the issue really is

is it a shudder in that the whole car reverberates
or
is it a stutter in that you briefly loose acceleration

makes a difference.

 

The front of the car reverberates. It only happens when I am accelerating at slower speeds to reach 40 mph. [example: Driving behind someone who is keeping a slow pace.When I reach 35 to 40 mph, the front end Shudders. If my foot is not on the pedal, everything is fine. If I am on the open highway or on a country road and I put a little more pressure to the gas pedal, everything is fine. Seems like it is coming from Transmission.

 

Car currently at shop. Mech says I need two transmission sensors. Does this sound right? Dealership said I probably need P1 and P2 relays,not sensors, bring the car to them and let them check it. ?????????

 

Depends, does your local mechanic specialize in Volvo?

 

he does. Says they would have to take apart transmission to replace. This doesn't sound good for a transmission only 3 years old

 

took car to dealership. Let mech drive and experience shudder. They installed new software for transmission. Car still shudders at 40 mph while lightly pressing on gas pedal. They also said I have a cracked "Sub-frame bushing". I will replace. If shudders continues, back to dealership.

 

had the same problem on my s60 was the alternator going about $150. the shuddering got worse, till you couldn't go 10 mph. alternator fixed it runs great now. transmission shifts using electric, didn't know that at the time.

 

I'll look into that. Thanks. Can I change a sub-frame bushing myself? or do I need a mech or special tool?

 

I'm having this problem on a brand new 2009 V50 - shudders under acceleration between 20-50kmh, no loss of power, just feels like the car is shaking under the power of the engine but for a $50k+ car, this isnt my expectation. Any suggestions as to what causes this?