Hey all, for about 6 months to a year now my Volvo s40 2005 has been harsh on down shift making my car stutter. It happens most when slowing at a light or slowing down to turn a corner. It’s now picked up a new habit where as I’m driving it feels like it’s sticking and I lose power while driving. It’s just very jolty. We’ve replaced everything you could think of other than the tranny lol. Obviously next is a trip to Volvo to see what they can find, but has anybody had an issue with this? It’s getting really bad to drive, but I love my car and don’t want a new one.

 

manual or automatic? any check engine lights or codes being presented? When you say you've replaced stuff - what? What other tests have you done - ie compression test, fuel pressure test, run time OBD2 engine monitoring etc? Have you inspected the intake - ie MAF, tubing, vacuum lines, throttle body etc? My general experience here is you either have a fuel mixture issue or a spark issue. Fuel mixture can be all sorts of things ranging from intake air or exhaust leaks to throttle body/MAF/MAP etc. Spark issues can be coils, plugs (including incorrect plug choice), wire harness/connector cracks. You mechanic may need some diagnostics time before recommending a plan of action but this doesn't sound like a "sell the car" scenario to me.

 

I'll bet dollars to donuts that your problem is the linear shift solenoids are gummed up / worn out. That'll cause the harsh downshifts, and the "flare" you're experiencing between gears when upshifting. It might be worthwhile to do a transmission fluid drain-and-fill, but that seems to be more likely to "fix" other types of cars more than Volvos (I tried a few D-N-F's without much improvement). The good news is that swapping the solenoids isn't expensive (IIRC, around $100 for all three) nor is it a huge job - I did it in a couple hours, including making a video of the process.