Misfire when warm

Hi all, first post so hello everybody! I bought number 52 a month or so ago and all has been well until this week the car has developed a misfire on part throttle when warm it started as a slight miss on part throttle at low rpm now it does it through the Rev range on and off even at full throttle, I also experience a slightly lumpy idle then it clears I?ve been advised a coil pack maybe breaking down?
ive just had a quick look at the car and noticed a small amount of fluid around the first Coil on the right bank as you stand in front of the car also the coil isn?t tight like the rest are so I?m guessing the bolt isn?t tight enough
I think this fluid must be coolant as it?s near the top hose and water would of boiled off ages ago
So should this coil be tight? and could this coolant be causing the coil to break down?

There is oil in the ignition coils, it could be that is leaking out.

A good quality of set of uprated coils is £200 and are well worth the money.

If you read on the Ford forums many people across the pond find the coils can start failing from 60k. While at it unless you have a record of when they were last replaced pop a set of plugs in at the same time with some copper grease on the threads.

Steve

From your description of the location, and if the fluid is coolant, then your leak is possibly at the underside joint of the alloy crossover-over piece and the intake manifold at the thermostat end. Leaks do occur there (I have had one) and unfortunately are generally caused by "plastic rot" at the gasket between them. Hopefully not, since that requires a new intake if it is. If so, the coolant leak has most probably caused the spark plug hole to fill up with coolant and short out the plug. Remove that coil, one 7mm bolt, and take a look. Incidentally not all coils may feel 'rock-solid'. Not a problem since the bolt should not be over tight, Ford say only 6Nm. They can easily strip the intake brass thread if you do over tighten. Fitting coil packs with dielectric grease is always a good idea anyway, but clearly any coolant leak would need fixing for other reasons too.

David

Best to remove and clean the windscreen washer jets from the bonnet and refit them using a bit of sealant as that is a common source of water ingress above the coil packs.

Another possibility for causing a misfire is the main engine harness plug at the back left side of the engine bay on the bulkhead (when standing at the front of the car). It's the connector with a bolt to retain it in place. Remove the bolt, unplug and check for slight corrosion and clean with a good deoxidising electrical spray like Servisol.

Ok, thanks for all the replies, I’ll pull the offending plug lead off and see if we’ve coolant in there it would explain the misfire but I’ll also check the harness connection as well, hopefully I don’t need a new intake!

Fingers crossed for you ! Let us know how you get on, but more importantly, consider joining as a full member, if you haven't already started sorting that out. Believe me, you will never regret it.

Lots of help and information is available here, but much is only in Forum sections which are closed to you until you do that. Best to send a PM to Tim and ask for a questionnaire.

David

Thanks David,I have joined as a full member i messaged Tim a few weeks ago and yes this site is superb,bit of a strange one the car,went out the other night it was around 15 degrees and the car ran perfectly then last night it was above 20 degrees and it miss firing again
Who's the best garage to service our cars? Its previously been to Austin garages in shropshire with the previous owner

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Originally Posted by Trower36

Thanks David,I have joined as a full member i messaged Tim a few weeks ago and yes this site is superb,bit of a strange one the car,went out the other night it was around 15 degrees and the car ran perfectly then last night it was above 20 degrees and it miss firing again
Who's the best garage to service our cars? Its previously been to Austin garages in shropshire with the previous owner

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I use Austin Garages too, even though I live in Holland, at least for anything major or needing experience with the 260s (actually near Burton-on-Trent in Staffordshire, not Shropshire). Excellent service and price, in my opinion, but often difficult to get an appointment.

Regular small service (oil, filter, brake pads etc) should be no problem for a good non-260-specialist garage though. Emphasis on 'good', as always! If you can, and I have managed to, try and get a garage to accept that you always provide the parts and materials. They may baulk at that, since most make a lot of dosh on supplying inferior Chinese stuff at dealer prices! Makes sure I get top quality 5w20 oil, K&N filters and the Pagid pads I prefer.

Was there any coolant under the COP in the spark plug tube, incidentally?

David

Sorry yes Staffordshire, there was a small amount of crystallized substance in the recess where the plug is on the front cylinder right side as you stand in front of the car, which is plug eight? i'm presuming it's at the back?

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Originally Posted by Trower36

Sorry yes Staffordshire, there was a small amount of crystallized substance in the recess where the plug is on the front cylinder right side as you stand in front of the car, which is plug eight? i'm presuming it's at the back?

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Yep. 8 is at the back, right hand side as you look at the motor from the front. That one gets the screen-washer jet/rainwater leakage sometimes. I guess yours is on the front end of the motor on the same side, nearest to the radiator hose > thermostat entry? If so that is or has been a leak and need investigating. If you have a crystalline deposit you had/have coolant there. Coolant may be sitting still inside the rubber tube around the spring plug contact and needs cleaning up anyway. Get some dialectric grease then, not that that will actually cure any leak if there is one of course!

David

Probably a good idea to get on to the last owner if possible, to see if the deposit is perhaps a result of an 'historic' leak, now resolved, maybe? I had a bad coolant leak from a badly installed intake manifold assembly, which caused a misfire even after the leak was resolved and everything dried up. The misfire persisted as a result of the leaked coolant having rusted the long spring inside the COP rubber tube, making for a poor or intermittent contact with the plug.

David

The spring plug contact looked clean but to be fair i'll give it a clean and compare it to the state of a non contaminated lead,there is no coolant leak at present i can detect? Whats your thought's on removing sound deadening under the bonnet to aid cooling?

It was never mentioned at the time of sale the car has run perfectly for the first 300 miles i've had it,i'm going to check plug 8 as we did get caught in a huge downpour a few weeks ago i'm now wondering if water ingress in there has caused an issue

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Originally Posted by Trower36

...Whats your thought's on removing sound deadening under the bonnet to aid cooling?

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I have removed the under bonnet sound deadening on mine (and kept it so that it can be put back to standard if required at a later date), but it is a supercharged engine so I expect that it can create a bit more heat than a standard 260. Some have put bonnet vents in the bonnet to aid cooling, but that is a bit of an undertaking.

If I were you, I would check when your coolant was last changed and if it was over 2 years ago then I would change it along with the radiator cap. Also if your radiator has not been changed, it might be worth checking that too. When I checked my radiator (factory fitted original), the bottom of it was bowed downwards. I did not want to risk it blowing when out on the road, so it got changed.

After changing the radiator and coolant, the under bonnet temperatures ran significantly cooler. Not scientifically temperature tested, but my face was able to stand the under bonnet temperatures more easily when I opened the bonnet after the rad and coolant change :)

PS If you do remove the under bonnet sound deadening, then sealing the windscreen washer jets becomes even more important as there will be no sound deadening to absorb any water ingress through the washer jets. It's a very straightforward job.

I guess you should decide if you have a problem before looking for a solution. For example, I've never had any engine heat problems, let alone overheating, so my bonnet sound-insulation is certainly still in place, as is the undertray.

May have something to do with my 'Olive' being a Rover (auto box) though, which means that under normal conditions the engine will probably be revving much less than when driving in a somewhat 'spirited' fashion with a manual box? Hard to say. I imagine the weight of the right foot may have something to do with it too! A motor being asked to work hard and run at higher rpm, is likely to generate more heat, I think.

David