Q: My neighbor has a 2001 Jaguar XJ8 with 53,000 miles. The car sits in a garage for months. He keeps the battery on a trickle charge. Recently, while driving it, the engine had gone into a "safe" mode, what Jaguar calls a "limp home" feature. "Transmission fault" reads across the dash. If you shut the car down and wait, it clears itself and you can drive normal again. He brought it to a transmission place, and they found no issues. (It had been towed in, and I'm guessing when they started it up it had cleared itself with no codes.) There is no pattern to the problem, i.e., when it's hot, cold, short drive, etc. Any thoughts?
A: The Jaguar is a great car, no doubt. However, like all cars and SUVs, there are going to be problems.
The first service I would perform would be a BG transmission flush. This will eliminate any intermittent sticking valves. The vehicle is more prone to sticking transmission valves because it sits for long periods of time with dirty transmission fluid. Turning off the engine and restarting it cuts out the transmission pump and all hydraulic pressure wanes. Without hydraulic pressure, the valves can return to their normal home position.
If the problem persists, driving the car with a recording device plugged into the ALDL may be the way to go. The technician will be able to download the information and find out exactly where the problem lies.
Q: I have a 2000 Ford Explorer, two-wheel drive automatic with a 4.0 SOHV 245 cubic engine V6 with 125,000 miles. It runs well, but every once in a while the check engine light comes on and it starts to skip. It's always the No. 4 cylinder. It has a new No. 4 cylinder; we put a new plug in, and it ran fine for a while. Then it started skipping again. So we put a new wire on No. 4, and it was firing for a while and it started skipping. Do you think it could be the fuel injector not working? Or electric control module where the wires plug in? Any suggestions?
A: There are so many ways to go about this problem that it's best I touch on just a few of the popular diagnostic methods.
The simplest would be to put a basic vacuum gauge on the engine and look for a pulsating needle. The pulsating needle would indicate an internal engine fault. If the needle pulsates, of course, then you can check for the cylinder compression, etc.
The biggest telltale factor is the condition of the spark plug when it comes out. That may reveal a bad piston ring, an intake manifold leak or even a lean-running fuel injector. To eliminate the fuel injector issue, you could move the injector from cylinder 4 to its neighbor and see if the problem follows. Don't forget to change the sealing "O" ring when you do this.
At our shop, we have the diagnostic computer that hooks right up to the data link plug and performs a cylinder balance test that gives information that is a bit more accurate. However, this is a very expensive tool, and quite a few shops do not have the dedicated Ford diagnostic equipment.
Car Care Tip: Tires more than 5 years old are very prone to dry rot. Dry rot makes a tire very susceptible to blowouts. Have your repair facility look over your tires next time you are in for service.
Larry Rubenstein is a master technician who owns a North Shore service station. His column appears every Saturday. Write to Larry at The Salem News, c/o Auto Scanner, 32 Dunham Road, Beverly, MA 01915, or send e-mail to firstname.lastname@example.org.