29 replies to this topic

[dml2]

Recently, I drove a Ford Mondeo 2.0 TDCi diesel hire car, June 2017 reg, 8094 miles on the clock.

I was driving in 6th gear at 70 m.p.h. then I braked while approaching a roundabout. At approx. 20 m.p.h. I put the clutch down to 'block change' into 2nd gear but the engine cut out. I kept the clutch down, coasted onto the roundabout (it was clear) and took the first exit. Fortunately this was a farm track with no traffic so I was able to stop safely and restart the engine.

I phoned the car hire company and said that the engine had cut out while the car was moving at about 20 m.p.h. so I thought there was a fault and I didn't consider that the car was safe to drive. They said it could be the auto stop/start. I said that couldn't be the reason as the auto stop/start should only work when the car stops. Then they suggested that I should call the AA.

 

I asked the AA patrol man to plug in his OBD scanner to check for faults but he found no fault codes stored. He then told me that it is a 'characteristic' of high-geared modern cars with common-rail diesel engines and 6 gears that the engine cuts out below a certain number of r.p.m. He wasn't able to give me a precise figure but I continued my journey making sure that the revs never dropped below 1000 r.p.m. while decelerating and the engine didn't stall again.

I read elsewhere on TalkFord that on the Mondeo Mk3 diesel, the ECU stops firing the injectors below 650 r.p.m. and that 6th gear is 2000 r.p.m. at 76 m.p.h. If it's the same for Mk 4 then 650 r.p.m. would be 24.7 m.p.h. which would explain why the engine cuts out if you decelerate to 20 m.p.h. in 6th before changing down.

Has anyone else had a problem with this 'characteristic'? Does anyone else think it is unsafe? I think that car hire companies should warn their customers about this.

[Mondygeek]

From what I've just read I'm assuming at 20-25mph you was still in 6th gear before pressing down the clutch? If that's the case then that speed for that gear is way below the engines stall rpm and would just put that down to your late change in gear rather than a fault with the car. I'm assuming the car gave a judder right before it stalled?

[dml2]

From what I've just read I'm assuming at 20-25mph you was still in 6th gear before pressing down the clutch? If that's the case then that speed for that gear is way below the engines stall rpm and would just put that down to your late change in gear rather than a fault with the car. I'm assuming the car gave a judder right before it stalled?

Thanks for the reply. I mentioned Mk4 but it's Mk5. I probably had slowed down to 20 - 25 m.p.h. in 6th gear but I didn't notice any judder. I just pressed the clutch to change gear and noticed that the engine had stopped. This is new to me, normally if the engine is turning then it will pick up and run at idling speed. If the ECU doesn't fire the injectors below 650 r.p.m. then how does the engine start in the first place?

 

I'll watch out for this in future but sometimes a late gear change would be unavoidable, such as traffic on a motorway slowing down unexpectedly.

[TreborB]

David, I cannot get my head round this.

If you were driving at 70 in 6th, approaching a roundabout, you obviously slowed down as you approached the roundabout so why were you still in 6th gear when you got to the roundabout at approx 20mph.

Who says the injectors cut out on the Mk5 at 650rpm

Late gear changes unavoidable?? If you are in traffic why are you in 6th gear.

On a motorway, emergency stop, well if you dont get chance to change down and upon coming to a complete emergency stop, what the heck if it stalls anyway.

I would suggest that your incorrect diving caused the cut out at the roundabout.

[Bigcol1]

This has been happening to me every 2000 miles for the past 9 months. but its not rev related. I have an auto 180hp and it just cuts out whilst normal driving at 70mph. usually whilst on cruise control. been into dealers 6 times and had loads of bits changed but still no fix. it always happens just as I apply a light throttle and then as if by magic the engine dies. No fault found, no code and Ford don't have a monitoring device that records so no luck. getting to the point where I need to get rid of the car. Dash just shows a nice picture of a spanner with the comment "see manual".

 

restarts fine after you have coasted into the slow lane then to a stop. put it in park, turn off. Ive had a failure in the Dartford tunnel and on the M25 with no hard shoulder at night in the rain so its a bit scary.

Edited by Bigcol1, 05 December 2017 - 07:19 PM.

[TreborB]

So Colin, your problem is totally different to Davids experience.

Your veh certainly does have an actual problem Colin if the engine is stopping/cutting out at your speed and revs

 

Does the fault ever happen when cruise control is not in use

Edited by TreborB, 05 December 2017 - 07:25 PM.

[Bigcol1]

Its happened whist on adaptive cruise and off. Always at motorway speeds, however as 90% of the time is on Motorways and that's no help. Ford had it for an extended test and drive 60 miles! it now happens every 2 or 3 thousand. ( monthly for me)

 

I think its a fuel metering problem or something wearing as it used to happen only in hot weather last couple of summers but now its happening more frequently and in colder weather.

I was looking into some sort of OBD reader for a laptop myself so I could check for a code at the actual time if cut out.

[TreborB]

Hi Colin,

just a stab in the dark. would have been easier if it only cut out when CC in use

sorry I can't help with a diagnosis on the fault as I don't do diesels.

There are a few guys on here who can recommend a decent OBD reader etc. Hopefully one will pop the info up soon.

 

Or you could ask the question about a reader by posting in the Mk5 Mondeo Electrical section, or the

Tools and Test/Diagnostic Equipment Section found in the main menu

[nesmagu]

20mph at 6 gear and you wonder why the engine cut off? lol.

[Jimbbobw1977]

Of course the engine will cut out at 20mph in 6th gear! It’s not a safety issue it’s driver error. Some cars this maybe feasible but not this or a lot of other cars for that matter.

We have Corsa 1.3d’s at work, and these I’ll simply not do less than 25mph in 5th gear before it will cut out