Surging At Cruise Speeds?

[kissy]

Ok what I think I’ve narrowed the problem down to is a faulty O2 sensor, as the surging only happens when the car is cruising, the car is using closed cycle cruise mode. So if the O2 sensor is intermediately giving out the wrong voltage it will cause the engine to run to lean or rich causing the surging and loss of power.

So on the weekend I’m going to replace the O2 sensor and see if that fix’s the problem.

[SLVRXRT]

I had the same problem with my Rex a while back. It was a faulty O2 sensor.

[kissy]

Well it turns out it was the oxy sensor, the wire's were caught under the heat shield and rubbed up against the exhaust manifold. this caused one of the wires to wear all the way down to the conductor. This wire also happened to be the signal wire!! So the signal wire was earthing out against the manifold, thus the ecu getting the wrong signal!

[ratter]

Good to see you get it sorted out, good on ya for reporting back what the problem was

[firie386]

Well it turns out it was the oxy sensor, the wire's were caught under the heat shield and rubbed up against the exhaust manifold. this caused one of the wires to wear all the way down to the conductor. This wire also happened to be the signal wire!! So the signal wire was earthing out against the manifold, thus the ecu getting the wrong signal!

I've got this Problem on a 2002 BA XR6T. I have had it to ford quite a few times and they can't pinpoint it, although we have changed 3 coil Packs, TPS. They checked fuel pressure,turbo the coils again, reflashed it etc

Occassionally car stalls completely and check engine light comes on. It happens when cruising or with min throttle. This is particularly the case after coasting and then apply min throttle. Codes logged are running too rich & too lean.

Is there a code logged for oxy sensor gone?

Any ideas much appreciated

[senna_T]

Good chance it is the Oxygen Sensor Firie, considering the O2 sensor can control the mixtures, probably worth changing anyway