Q: I have a 2002 Mazda Tribute with a six-cylinder engine. When driving on the highway and coming to a steep hill, I'll usually downshift in order to keep the speed going. However, this causes the transmission to stutter. Any suggestions?
_Alan MacKenzie, Victoria, British Columbia
A: Your Tribute is equipped with Ford's CD4E transmission. To figure out what's going on, let's start by figuring out if the transmission fluid looks OK and is at the right level. Also, is the check engine light on? If it is, running diagnostics with a scan tool could point you toward the problem area.
Anyway, to check the transmission fluids, drive 20 miles and then come to stop. Slowly run the gear selector through all positions. Then, with the engine idling in park, remove the transmission dipstick, wipe it clean with a lint-free rag, reinsert, remove, and read. The fluid should be in the center of the crosshatched area. Fluid should not be discolored or have a burnt odor. If needed, top off with Mercon fluid.
Now regarding that transmission stutter: Does it occur prior to or during the fourth-to-third-gear downshift? To double-check, try this on a hill you're familiar with just prior to an anticipated downshift: Keep your right foot steady on the throttle, and with your left foot, press ever so gently on the brake pedal and hold. The torque converter clutch should release, increasing engine rpm slightly. Stay like this and bear slightly deeper into the throttle until the down shift occurs. Does the shuddering still occur? If it goes away, and the shift feels good, chances are the torque converter clutch was slipping. A valve body upgrade may fix this if caught early. If it's the shift that shudders, there's different trouble internally within the transmission.
A change of fluid is worth a try. If your symptom still exists, I'd seek out a sharp Mazda or Ford transmission tech to get to the bottom of this.
Q: I bought a new 2014 Corolla LE with a continuously variable transmission. When I accelerate the car from a standstill, I feel a slight vibration or hesitation that lingers until I pick up a little speed.
I have around 20,000 miles on the vehicle, and it gets good gas mileage. Should I worry about this vibration?
I think I've had this issue since getting the car. I have changed the engine air filter and added conditioner to the gas, thinking I might have sticky valves. I have not said anything to the dealer because, based on experience, I imagine they'd just say something like: "It's your imagination. Everything's working fine. If anything, maybe some dirty fuel."
I think I'm more curious than worried. I have been working on cars since I was a poor teenager. Back then, if I wanted to keep my car, I had to fix it. I did brakes, ignitions, exhaust systems, car body repair and painting, etc., so I am a little familiar with cars.
_ Ken Kraut
A: Are you still within Toyota's three-year, 36,000 miles warranty? If so, I'd hop on down to the dealer and have your complaint officially documented. Taking a test drive with the shop foreman would be my first request and, if there's an identical vehicle in inventory, compare your concern with it while road testing. It's difficult to say if there's anything wrong with your car. If an identical Corolla exhibits the same feeling, odds are there's nothing wrong. You don't want to let the warranty expire without at least one documented symptom comment or repair attempt.
