Engine misfire counts

Firstly the car is running well with good economy and performance.

When I run Pscan live data and look at misfires plug 0 and 1 report "0'
However plug 3 and 4 report "?"

I've checked the connections and cleaned the pack connector with contact cleaner but the error remains.

It's a 2004 1.6 TF

Any suggestion what to try next or should I just ignore it .

I had this on mine and I replaced the often neglected plugs and the fault went away . I keep on about the number of times I have seen verdigris between the coil pack and the plug lead where it plugs onto the coil, on several TFs I have worked on . Have a good look at that area . What mileage has the car done ? The coil packs and leads may need replacing .
Is the fuel level low in the tank ? Does the fuel filter need replacing ?
John .

Thanks. Since I bought the car I've replaced the fuel filter, fitted new NGK platinum plugs, replaced the plug leads all as a matter of course as it came with no service history. I cleaned the plug contacts when I first detected the error. The mileage is 107,000 but on a recent 1500 mile trip it averaged 46mpg and idles smoothly. I never let the tank get below ½ full - force of habit!. Coil pack was to be my next item to change but as it's only Pscan that threw the problem up I'll perhaps wait until next service time or swap coil pack 1 / 2 with pack 3 / 4 to see if the fault moves.

You say you replaced the leads . Did you replace the coil packs at the same time ? These cars are getting on now and coil packs don't last for ever . Do I take it that the miss fire code comes back when you clear it with Pscan ? Multiple miss fires could lead to damaging the CAT and the O2 sensors .

John

There are no error codes when I do the read and the yellow engine warning light extinguishes as soon as the engine starts. I only see the situation that Pscan reports “?” when reading live data with the engine running. Tick over is smooth and it accelerates strongly and without misfires. Is it just that Pscan is unable to obtain a valid status from the pack or ECU? I think a coil pack replacement will be done soon .

OK, well I've just re read the first part of the post and my TF did give a low speed miss and it logged a fault code that Pscan could both read and clear . Once I sourced the problem and fixed it the code never came back . A bit of a head scratcher this one . I would be inclined to let it develop if you don't feel the engine miss fire ( which I did with mine ) and it runs well .
John .

John, I appreciate all the help and as I said earlier I think new packs will be on the cards. Though to quote a friend if it isn't broke don't try and fix it

This is the Pscan screenshot. The coil charging times vary as the engine runs so Coil 2 is often less that Coil 1. Misfire sensor shows no errors and misfire detection is possible.

The difference in charge times in miniscule, about a 0.01% difference so not enough to affect things.

Thanks, yes the counts for both coils varied as the engine ran . Pscan still not able to diagnose misfires or not on cylinders 3&4. Academic I suppose as the car is running perfectly.

Duncraig wrote:

Thanks, yes the counts for both coils varied as the engine ran . Pscan still not able to diagnose misfires or not on cylinders 3&4. Academic I suppose as the car is running perfectly.

The problem is that the factory T4 tool doesn't appear to be able to read cylinders 3&4 either. It's a bit difficult to make pscan do something that no other tool can do.

Thanks for an answer from the guy behind Pscan. Now I know what the issue is I can sleep easy! Pscan is amazing and I’ve successfully programmed In two new Pektron key fobs.