Engine won't turn off - intermittent

[HarryHornby]

We've got a weird one on our 04 reg Skoda Octavia. 1.9 turbo diesel


Car was unlocked yesterday morning and when the wife and kids got in the dashboard lights (battery etc) were on before the key was in the ignition.  Apparently it took a couple of goes to unlock too (remote key fob)


Did the school run, all ok.  Got home, turned off ignition, pulled out key, engine kept going.  Normal revs, just as though the ignition was on.


Told the wife to stall it, she couldn't go forward so put it in reverse.  As soon as reverse was selected the engine stopped.


It's done it on and off all day, keeping going more than it's stopping when it should.


I've put a very basic engine fault finder thing on the engine management socket in the car and it came back with no errors.


I've just gone out to the car and started it up, it' was a little sluggish for about 20 seconds upon starting then reved fine, a "not normal" shooshing noise (not loud) coming from under the bonnet (left hand side as you look at the car).  This stopped when the car revved fine.


Turned off ignition but car kept going.  Engaged reverse and it instantly stopped.


I've read about diesels overrunning and blowing themselves up due to oil leaking from the turbo but it's not that I am sure, revs are fine, no white smoke.


I'm guessing electrical...... strange how when reverse is engaged it stops the engine normally, I wonder if the turning on of the reversing lights is doing something?


My other thought is fuel pump?  Diesels stop by stopping the fuel pump, correct?  Maybe fuel pump not cutting out?

Battery??

 

I drove the car to work this morning to get a feel for how it's driving.  I pulled off the drive and stopped the engine (to swap the cars over) it thought about not stopping for a split second then died as normal.

 

drove the 20 miles to work hoping that a good run and some heat might dry out any possible water in electrics issue.  Car drove well, pulled well, normal fuel economy etc etc.  Got to work and it turned off ok.

 

Will see what it does on the way home.

Any ideas lads.

[cheshire_cat]

sticky main relay?

[morrispaul]

Hi harry.......iam surprised the fault finder didn't find any errors.......what sort of scan tool you using ?

[HarryHornby]

I don't think it's a flash one, a friend lent it to me and quickly showed me how to use it so I'm afraid I'm no genius.  Knowing him it's cheap from China, it's called a CAN OBD ii memoscan - U480

 

Things have now moved on a little.

 

Car was good as gold for 2 days, that was after I had given it a good run to work (20 miles each way) rather than its usual 2 mile school runs.

 

This morning after being back on the school run for a day the wife tried to unlock it with the fob and it wouldn't unlock at all.  Looked in and the dash lights were on (oil battery etc) opened with key but car wouldn't start at all.

 

I suggested to her that the battery has seen a good 7 years service and it probably knackered.

 

Took it to a local car parts place, they tested it and said battery is good, no duff cells but very low on charge.

 

They are decharging it completely for us before re-charging it (no charge for that performing that service either, so a thumbs up to them).

 

We've got it booked in with an electrical chap on Monday.  It looks like it's a bit more than the engine not turning off.

 

Alternator not charging battery?  Hopefully we'll find out more on Monday.

[kentphil1]

Melting fusebox on top of the battery?

[Leeboy]

If you've got open circuits in your electrical gremlins then sounds like the battery is discharging when it should be all off bar minute feed to radio and flashing door led, and stuff like that.

Hope your electrician comes up with answers, all seems a bit weird!

[HarryHornby]

FIXED IT!  although we are now £420 lighter!

 

Took the car to an auto electrician who came very highly recommended by a fair few people.

 

He found a rotted loom in the back LH corner, which is where the windscreen washer pipe had popped off a couple of years ago, I did dry it, but I suspect not all of it.  He replaced that.  This could explain the act of reverse turning the engine off (shorting out?)

 

The Central Convenience Module had a fault on it and had caused some burning on some attached wires.  This controls the electric windows, central locking and other bits and bobs, this was what was causing the big drain on the battery.  He replaced that.

 

He found that the housing around fuse 7 was melted and associated wires were burnt too.  replaced.

 

Apparently, an acceptable drain on a car battery is 0.5amps, he's got ours down to pretty much zero apparently.

 

SO, fingers crossed, it's all fixed.  Just got to pay the Father in Law back now!  

[cheshire_cat]

glad you're fixed and thanks for the feedback :sun: