Engine Cut Out
Discussion
Hi all,
Long time lurker first time poster.
I have the notorious 2.2D Mazda 6 (2016, Skyactive engine). It has about 80k on the clock and has generally been well serviced. Previous owner had a late oil change about 40k miles ago, most recent service done in November.
Driving on the motorway a couple of weeks ago the car cut out as if it had stalled. It seemed to recover itself but sounded very rough, so I pulled over and had the car recovered to my local garage. I tried to start the car to move it out of the middle of the parking lot, and it just wouldn't start so I left it. Garage had a look and said it needs a specialist. They suspected oil starvation or something "low end", although they may have a been a bit stumped and I think suggested this from Google searches they'd performed.
It sat there for a couple of weeks for a variety of reasons and I finally had the car towed to my home yesterday. To my surprise, the driver started the car and drove it on to my drive without issue, save for an acrid smell from the exhaust. Otherwise, it sounds totally normal. I took it out for a drive and it seems to be performing normally, absolutely no sign of the previous fault, no codes, oil, engine, dpf lights etc. It might be a little nosiy, but not sure and certainly not noticeably different.
So I'm a bit stumped. The garage were under the impression that the engine was knackered and needed a total rebuild, but it drives absolutely fine at the moment (admittedly haven't taken it up to motorway speed, only briefly up to 50 on a local A road). Due to the smell, I'm thinking significant carbon build up in the engine and egr valve, maybe this shifted and blocked the exhaust causing it to lock up? DPF readings are normal, although maybe the sensor is dead/pipes blocked. I noticed this morning the car seemed to take a long time to get up to temperature (blue coolant light on for much longer than usual).
Any ideas very welcome.
Long time lurker first time poster.
I have the notorious 2.2D Mazda 6 (2016, Skyactive engine). It has about 80k on the clock and has generally been well serviced. Previous owner had a late oil change about 40k miles ago, most recent service done in November.
Driving on the motorway a couple of weeks ago the car cut out as if it had stalled. It seemed to recover itself but sounded very rough, so I pulled over and had the car recovered to my local garage. I tried to start the car to move it out of the middle of the parking lot, and it just wouldn't start so I left it. Garage had a look and said it needs a specialist. They suspected oil starvation or something "low end", although they may have a been a bit stumped and I think suggested this from Google searches they'd performed.
It sat there for a couple of weeks for a variety of reasons and I finally had the car towed to my home yesterday. To my surprise, the driver started the car and drove it on to my drive without issue, save for an acrid smell from the exhaust. Otherwise, it sounds totally normal. I took it out for a drive and it seems to be performing normally, absolutely no sign of the previous fault, no codes, oil, engine, dpf lights etc. It might be a little nosiy, but not sure and certainly not noticeably different.
So I'm a bit stumped. The garage were under the impression that the engine was knackered and needed a total rebuild, but it drives absolutely fine at the moment (admittedly haven't taken it up to motorway speed, only briefly up to 50 on a local A road). Due to the smell, I'm thinking significant carbon build up in the engine and egr valve, maybe this shifted and blocked the exhaust causing it to lock up? DPF readings are normal, although maybe the sensor is dead/pipes blocked. I noticed this morning the car seemed to take a long time to get up to temperature (blue coolant light on for much longer than usual).
Any ideas very welcome.
Edited by rl88 on Saturday 12th February 13:46
A sudden failure says electrical, not mechanical, to me.
Something that interrupted either fuel supply or ignition. Go around the engine wiggling wires until the engine stops again?
When it does what you last wiggled may narrow it down. Then inspect the codes again, they might have reset during its layover.
John
Something that interrupted either fuel supply or ignition. Go around the engine wiggling wires until the engine stops again?
When it does what you last wiggled may narrow it down. Then inspect the codes again, they might have reset during its layover.
John
Interesting one.
No I don't think it would cause it to lock up due to carbon build up at motorway speeds.
If could be that the garage kept cranking it due to which unburnt fuel is soked in the dpf. N now its smelling ? How long did you drive it for ? Did the smell improve ?
Did u have any codes when it first died ? N failing crank sensor could cause that. However it usually throws a code.
When it does not start do u have the rpm gauge moving while cranking?
If u have a scanner plug it in n see if u can read data from the maf, fuel pressure, fuel temperature and crank. (However difficult to tell what will be the correct values )
If its starting now collect the data and compare it when it doesn't.
And yes as said previously pull on the wiring harness n see if it acts up again.
No I don't think it would cause it to lock up due to carbon build up at motorway speeds.
If could be that the garage kept cranking it due to which unburnt fuel is soked in the dpf. N now its smelling ? How long did you drive it for ? Did the smell improve ?
Did u have any codes when it first died ? N failing crank sensor could cause that. However it usually throws a code.
When it does not start do u have the rpm gauge moving while cranking?
If u have a scanner plug it in n see if u can read data from the maf, fuel pressure, fuel temperature and crank. (However difficult to tell what will be the correct values )
If its starting now collect the data and compare it when it doesn't.
And yes as said previously pull on the wiring harness n see if it acts up again.
Thanks guys. Had a fiddle with the wiring and seemed to make no difference. The smell has faded after driving it a bit.
The stats that are standing out to me on the scanner are with the EGR, which doesn't seem to be moving at all. Can't find any data on the CPS but think that might be one to look at.
Error is stuck at 99%. Is this normal?
The stats that are standing out to me on the scanner are with the EGR, which doesn't seem to be moving at all. Can't find any data on the CPS but think that might be one to look at.
Error is stuck at 99%. Is this normal?
Edited by rl88 on Saturday 12th February 16:46
Edited by rl88 on Saturday 12th February 16:46
The EGR figures do seem to be suggesting there's a problem with an EGR valve (is there more than one on that engine?) and an EGR valve is the sort of thing that can suffer age related failures or simply stuck due to dirt. Since the ECU is reporting demanded and actual position I assume it's electrically operated so if you can locate it, you may be able to test it in situ to at least check whether it's moving.
Hi guys,
Thanks for your help.
I think the EGR valve is sufficiently inaccessible that this would be one for a garage to look at.
I think the smell may actually be a burning oil smell. Have spoken to an engine specialist just now who thinks it may be that the turbo is failing and allowing oil in to the engine (I think that's what they said, might not have fully understood). If poss I'm going to have them take a look at it.
Will update either way.
Thanks for your help.
I think the EGR valve is sufficiently inaccessible that this would be one for a garage to look at.
I think the smell may actually be a burning oil smell. Have spoken to an engine specialist just now who thinks it may be that the turbo is failing and allowing oil in to the engine (I think that's what they said, might not have fully understood). If poss I'm going to have them take a look at it.
Will update either way.
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