Mazda CX-7 Surging During Acceleration

taz6

2007 CX-7 GT with 50K
Recently had a problem with the engine surging/losing-power during acceleration. Felt at first like a transmission problem as if the tranny was slipping, but with no bang. Ran fine at both idle and cruising speeds, but struggled to accelerate. CEL never came on.
Went to the dealer and was told their is a service notice from the manufacturer that the Oxygen sensors are not reading properly. Technician with computer took the vehicle out and confirmed that one of my Oxygen sensors is not reading correctly, but is within spec's (?) so their is a loss of performance but no CEL. Car runs great again. Not under warranty unfortunatley so cost $300+.

wwest

Oxygen sensors are only in the mixture control "loop" at low engine loads/loading, idle, constant speed cruise, etc.

Under acceleration the MAF/IAT sensors are used for mixture control.

taz6

wwest, thanks for the clearafication on the components.

Net result is that one of my oxygen sensors has been replaced (new part is obvious from looking under the hood at exhaust) and the car runs great again.

My point is that as soon as I walked into the dealership and described the problem they new what it was and told me their was a service notification from Mazda. As an owner of one of the first CX-7 i want people to know that what felt like a major tranny problem was a minor sensor issue.

inka2002

My CX-7 with 75K is showing similar signs of surging. This has occurred for some time when in the manual mode and in 1st gear, extreme surging. Now this is occurring in all gears under acceleration. Plugs have been replaced, premium fuel and Chevron Techron as fuel injection cleaner is standard procedure. Tranny fluid fresh as well.

Curious as to what the culprit could be.

wwest

Check ATF level...

A too high level can be just as much a problem as too low.