Ford coilpack failing?

[sowen]

Got a little problem with my Rover P6, it's running newly installed Megasquirt with Ford EDIS4 doing the sparky stuff. Over the past few days after leaving the engine idling to get it upto temperature there's been an intermittent roughness and loss of power causing the engine to die. It's hard to tell if it's an ignition misfire or not, spraying water onto the exhaust primaries when it's in the process of not wanting to run doesn't show an obvious colder cylinder.

It has a wideband lambda fitted and that goes off the scale lean when the loss of power happens, sometimes the engine will slowly rev up and others full throttle doesn't do anything as it's about to stall. I've even plumbed a pressure gauge into the fuel rail feed and it reads 40psi when running. Watching my laptop with TunerStudio running I can't see anything obvious on the fuel side to cause it to run badly. I've got a new set of spark plugs I'm about to try out later. The car hasn't got an mot so I can't take it out for a blast either. It was only doing it when at running temperature hot, but I've just moved the cars round and it did it again, loss of power and stalled.

Now the odd thing is turning the ignition off and restarting fixes it? This is making me wonder if I've somehow broken the coilpack and it's imminently about to fail permanently. Anyone have any thoughts?

[vitesseefi]

This could be heat-soak to the air inlet temp sensor. If this warms up the ECU will assume the incoming air is also warm (and therefore less dense) and back the fuel dose off accordingly. This causes lean running if the air isn't really as warm as the ECU thinks it is. You should be able to see if the IAT is going to daft readings on Tuner Studio. If the sensor is mounted properly in the airsteam then a few blips of the throttle should cool it and bring the fuelling back up.

This doesn't really explain why turning it off and on again effects an instant cure, unless it is just the extra airflow going through when you restart bringing the IAT back down. The other alternative is that it is simply corruption caused by electrical noise (which can sometimes be an issue with MS1 on 2.2 hardware in particular) and it is the reset that is sorting things. What happens if you try to restart without turning the ignition off first (ie no ECU reset)?

Heatsoak should be quite simple. Corruption due to noise could be a right cow.....

Nick

[sowen]

It leans off very suddenly, trying to rev out of it didn't work on the few occasions where it's still been able to rev. I think the air temps have been ranging from 25 to 40 degrees when the loss of power has occurred, will double check the readings the next time I get an opportunity.

The ignition has to be turned off to restart on the P6, to be honest I've not tried an instant restart before it powers off (I can beat the powering off on the key, still in early stages of testing to have consciously tried it yet). The electrical noise could be a likely cause, something to consider if it happens again.

I have just swapped the coilpack with another known good unit, no issues yet but it's too early to tell....