I have a Mazda 626 (V6) with about 150K miles and a funny engine racing problem. It occurs only when I’m going highway speeds (for me, 70MPH) and the car has been running for about 15 minutes. The engine will race, then chug and RPMs will drop down again, then it will race, etc. If I slow down, it will stop racing, but often start again as soon as I put my foot back on the gas pedal. If I don’t get on the highway (running 60MPH and under), the car is completely fine.
I’ve taken it to my mechanic twice; the first time had the fuel filter replaced, the second time got new spark plugs, but it’s still doing it. Any ideas what else it might be?
Manual or automatic?
This sounds like an automatic with a failing torque converter lockup clutch. Have you checked your tranny fluid lately? How’s it look? Does it smell?
Has the transmission been serviced regularly? If not it might be worthwhile to get the pan dropped, filter replaced and the cooler flushed real soon. For sure check the fluid level before driving again.
It sounds lie it is dropping out of overdrive and going into limp mode. Maybe a transmission fluid service can fix it, but if it has been too long since the fluid was changed, it may be the beginning of the end for this transmission. Try the fluid change, since it is the cheapest alternative.
Thanks guys, it was indeed dropping out of overdrive, but apparently the transmission is beyond servicing. Guess I’m going to be looking for a new car now.