Running really rough afterbreakdown.
 

My V40 2.0 petrol broke down yesterday. It was going along great then suddenly the engine stalls and it refused to start. RAC man thought it was timing issue, It went to my (ex) usual garage and they didn't want to know so it ended upstuck on drive.
Today I stripped it down and check all timing makes and it is spot on.
All four plugs firing but it runs really rough. It needs a lot of gas to keep it going for a few minutes then cuts out. Also cuts out if I try to drive it.
There is no MIL light on the dash and my code reader shows no error.

One strange thing though is once it cuts out after a short rough idle period no more than a minute the cooling fan comes on even though the rad is stone cold, it runs for a a minute or two then the fan goes off.

Does anyone have any ideas on this problem.?
Tomorrow I'm going to do a compression test.
Any help much appreciated, as usual its happened at a bad time to be carless.

it sounds like the engine temperature sensor has failed cheap and easy to replace

I did wonder about that, I disconnected it but it made on difference, if it should that is.
Is there away test it?
Thanks

Another thing I noticed was when I pulled the plugs out they had petrol on them. I was thinking perhaps a running rich problem, perhaps fuel regulator but then if the temp sensor is causing a problem I think it could be over fueling.

The RAC man squirted some brake cleaner in the air intake and it back fired on him. He jumped at that.first time I've witnessed a backfire for years.

I thinking its an over fuel problem.
But if the temperature sensor was causing it, my thinking is the ECU thinks the engine is hot, so switches on fan, but wouldn't the fuel be less if it thinks its hot as a cold engine needs more fuel until warm. If you see my thinking on that.

disconnecting wont do any thing as it needs to tell the ecu if its hot or cold to adjust the fuel accordingly

Yeah, I think I'd reached the point of just clutching at straws by then. I was cold wet and fed up. Disconnecting it would just cause an open circuit, which it could be if faulty anyway.

Fresh look at it tomorrow.

Further developments with this problem.
I fitted a different fuel pressure regular later and a new engine temp sensor and still no go.
I'm now wondering about the MAF sensor. Reason being when I unplug it and try to start it, it won't activate the MIL light and I think it usually does. though that is with the engine running which it now won't do either let alone run rough as before.
I have plug in a code read, no codes showing, RAC man found a timing code on his system but wasn't to sure about it and I've checked the timing, all OK.
Reading the live data with ignition only on and not running the MAF shows 0.00 and trying a start it still reads constant 0.00. But as said engine won't run so not sure what use these reading are.
Another reading that seems out of place to me it the FuelSys1 it shows OL usually its CL. So not switching to a Closed loop and that would explain the over fuelling at the plugs I think.
Both o2 sensors read 1.275 not running. I don't think I'd expect to see a difference between them until th`e engine is running.

Any thoughts anyone?

Another few hours spent on the V40. I did a compression test, just in case, and everything seems fine, all four cylinders gave 170 reading.

As to the starting problem I think I found it.It seems there is no voltage getting to the MAF sensor. Reading between the thicker red power in wire and earth is a big fat zero. I double checked the fuses and changed the relay just in case and popped the bottom of the engine fuse box but nothing looks wrong.

I guess it might be a problem with a wire in the loom or the ecu .

Are there any air leaks in the intake system at all? And did you give the MAF sensor a squirt of contact cleaner, just in case?

I had a good look around for air leaks, sprayed around the vac pipes with cleaner but al seems fine there. I did cleaned the sensor with MAF cleaner but I wasnt getting power to it. I eventually found a suspect part on the loom and repaired it and now it starts.
Took it for a run and it ran rough, revs droping and total lack of power going up hill then the MIL light came on giving MAF failure or short. I've decided to order a new MAF I really can't see what else it could be now. It should come for Thursday, everything crossed, it solves the problem.