Jerky after driving home in rain

[ex-Chinese Dave]

I drove home last night and from the start the car was perfect. I went through one large puddle, but not quickly and also there was a little standing water on the motorway. Once I came off the slip road I could feel that the car was very jerky below 2000 RPM. It starts fine and runs fine above 2000 revs. This morning I took off the inlet manifold and made sure there was no water down the plug holes. I didn’t see any moisture at all and I gave everything a good spray of WD-40. I’ve re-fitted everything and I’m now on a test drive, but I’m not convinced everything is perfect. The car is a 172 Cup and has just recently been fully serviced, it’s been running perfectly. Could it be something to do with the O2 sensor that may have gotten wet and will clear itself? I’m a little baffled as it wasn’t like I went driving through a river.

 

[JamesBryan]

Worth checking the engine bay fuse box.

 

[ex-Chinese Dave]

I've checked the fuse box. Nothing looked damp but I took out the fuses and relays and gave them a squirt of WD. Hoping this will work later when I go out.

Under the car, on the passenger side, I could see some wires going into a connector. Do I take it that that is for the O2 sensor? I've given that a WD, too.

 

[JamesBryan]

O2 sensor wires/plug joins around the rear of the subframe iirc

 

[ex-Chinese Dave]

O2 sensor wires/plug joins around the rear of the subframe iirc

Could that be the problem? I'm sure it gets soaked when ever it rains, not just after going through a few big puddles.

 

[JamesBryan]

Could that be the problem? I'm sure it gets soaked when ever it rains, not just after going through a few big puddles.

Plug is weather sealed and it's up on top of the subframe (or should be), so shouldn't really be a problem unless there's a dodgy wire.

 

[Matt Cup]

Does yours have the shield in front of the alternator? If it’s missing could water ingress there cause issues?

 

[ex-Chinese Dave]

Does yours have the shield in front of the alternator? If it’s missing could water ingress there cause issues?

I’m not sure without having a look. What would it expose if it’s not fitted?

 

[ex-Chinese Dave]

Well it seems to be back to normal now. I put it into 4th gear at 1200rpm and it sluggishly pulled away as opposed to what it was doing before which was jerking forward. I can still feel sometimes it seems to cut whilst pulling away in low gears from below 1500rpm as per this thread ( https://cliosport.net/threads/o2-sensor-fault.851384/ ) but at least the problem caused by the water seems to have gone.

 

[Matt Cup]

I’m not sure without having a look. What would it expose if it’s not fitted?

It just covers the alternator. It was a bit of a long shot as to it causing the issue you had though.