Intermittent revving issue

[staffsmod]

Hi! Hoping someone might have some ideas about some intermittent problems i'm having on my '59 1.2 Fabia. About 6 weeks ago I was moving my car to let Mrs off the drive and when reversing back the engine stalled. I started it up again and started moving and it stalled again and the low oil pressure warning pinged (not done this before or since). It wasn't in a great position, so I started it again moved it an extra meter and it stalled again. It was due a service anyway, so it went and had a full service. I told the garage, but they couldn't see anything wrong and there were no fault codes.

 

Everything seemed fine after the service for a few days, then occasionally at idle it would rev up and down a bit and when putting the clutch in while moving the revs would drop massively - if I was stopping they'd dip <500 and the car would shudder like it was about to stall, but never did. This happened maybe every other day for just 1 trip (out of 6 in a day, quite short). One of the things I'd read was maybe bad fuel, so I got some better stuff after about 1 month and that seemed to help - it was only nearly stalling on 1 trip a week or less.

 

Yesterday morning it was a bit stally which I thought could be low fuel related (petrol light on) and it was stally on my way home too. When I put it in reverse to park, the sensor did a long beep and the display went back to the radio. Back to neutral and into reverse again and same thing. I reversed ok but the sensors weren't working. I turned the engine off and back on and it instantly revved up to > 3000rpm for about 2/3 seconds then back down to normal (8-100rpm). Tired reverse, same fault beep.  I turned it off and back on same thing happened. This morning it's driven fine and the reversing sensors are working as normal again.

 

Anyone had anything similar? I've googled the 3 things separately (revs up and down/reverse sensor beep/revving up on start) and found posts about all 3 saying could be battery related. Does that sound sensible? TIA

[xman]

First thing to try, put your battery on charge for 24 hours. If you have a multimeter, check the battery voltage, after the car has been stood an hour(engine off). Should be >12.1 volts, ideally >12.5 volts for a near full charged battery. If battery voltage is lower, the battery may be goosed and you should have it tested (FOC at most battery suppliers)

 

With engine running, the battery voltage should be around 14.3 volts showing alternator is healthy

 

In my experience that sorts the parking sensors out which will lock out if battery voltage is too low .

 

Stalling might be battery related as well, but I'm inclined to think ignition (coils or plugs). Did they change the plugs at the service?

[staffsmod]

Thanks xman. They did change the plugs in the service. I'll give that a try.

[delta925]

If the original battery it will now be well past good performance, if a replacement depending when fitted and the quality it too could be end of life.

[staffsmod]

It is the original battery, but I've tested it now and it looks alright - 12.4 after standing 14.4 when running. So not perfect but shouldn't be the cause of any issues

 

I've only had the parking sensor fault once since I posted and haven't had the ridiculously high revving on start. I've plugged it in and there are no fault codes. The only thing that stood out to me (but don't really know what to look for) was the coolant temperature which was around 63C after running the engine for a good while.