[vincentxc90]

Original owner of 2005 XC90, 2.5L T5 engine with standard front wheel drive. Got 90K mileage after 14 years almost trouble free (with min. repair besides standard wear out and maintenance). Never push hard or abuse the car on driving and the car is in garage down in NC all these years.

In last month, I start feeling some jerking on my gas pedal (or from the transmission) under normal (to mild) acceleration and/or going uphill. It happens when the transmission is either in AUTO MODE (likely in 4th or 5th gear) or in "MANUAL MODE" when set on 4th and 5th gear. The passager probably never notices on the ride.

The jerking felt like it is trying to catch up, may be once or twice and then it runs smoothly. Otherwise, the engine and the transmission are running smoothly at other time. Transmission fluid is good and was replaced 2 years ago.

Is this serious enough to spend $150 at the Dealer to do a diagnosis ? Or this is common for old Volvo that needs an software update on the Transmission Control Module.
Appreciate any advice or share your experience.

 

[vincentxc90]

2005 XC90 Transmission Issue

It turns out I have a bad ignition coil and two bad spark plugs. The ground of the spark plug (L shape) is completed vanished. The engine light was not on but the repair shop diagnosed them and pull the code for that problem. These set of Volvo plugs had only 30K miles and are in horrible condition. The original one (with 60K miles) were in much better shape that you can literately reuse them. What caused my spark plug to fail like that while the car has been running absolute fine ? I replaced the timing belt and water bumps 20K miles ago as preventive maintenance.

When I replaced my spark plugs, the only thing was I did not torque them, just use gut feel for the torque.

 

[850Rick]

You didn’t say what the shop found for the codes?