Was driving along and felt a misfire and the eml light flashed on off on off on off and didn't stay on. Plugged in my obd and got code pending p0308 misfire detected in cylinder 8.
Cleared the pending code but why didnt it stay as a stored code?
And why didnt eml light stay on. Car drives smooth like normal.

Thanks

 

Don't really know but the way the mis-fire detection works is statistics. So a single mis-fire won't set the MIL. As you get more and more mis-fires the MIL may be turned on and if you get a lot of mis-fires then the MIL will start flashing. This flashing indicates you are possibly damaging the catalytic converters by over loading them with fuel. This fuel will be burned inside the converter causing extreme high temperatures.

This is what damages or destroys the converter. They run hot anyway but will go very hot with fuel pouring into them.

Fix the coil it will come back! Check for oil in the spark plug wells.
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I also keep getting a catalyst below efficiency bank 1 code. Could they be related?

 

Ok I read JTIS and it says to test the catalyst efficiency obd monitoring system drive at operating tempreture for 5 mins without start or stop at between 1300 and 3000 rpm. Well I just did that and plugged my obd tool in and no stored or pending codes?

Dodgy sensor maybe? Really frustrating as I don't know whether I have a major problem to worry about or not.

 

With mis-fires it can give that error. So fix the P0308 first and then clear all codes and see what comes back.
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i had the p0420 code first and have had it for a couple of weeks, the chain jumped one tooth when the 1st gen tensioners gave a little work was done to replace them to 3rd gen tensioners and was told that the fault code could be because the timing was out and engine was running rough for some time.

knowing my luck going to need a new cat!!

anyone rough cost in uk? for ne cat fitted?

 

Maybe but clear all the codes first.
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Cleared all codes and drove for around 10-20 miles varying speeds and rpms. Only fault that has come back do far is the p0420 catalyst below efficiency code. Looks like its going to garage ASAP. Is it ok to drive in terms of damaging other car componants. Of cats got to be replaced so be it but should hurt anything else right?

 

Car gone into Ajc jaguar specialists today. Will let you'll know what happens.

 

The codes PDF (in JTIS and also in the stickies) explains when codes set. P0 codes follow the law (yes, law), so you could read up on OBD if you'd rather do it that way (codes PDF is much shorter). I'd have a very close look at cyl 8 in case it has damp/dirt/oil - or just replace (or swap) its coil (assuming plugs are OK).

 

Ok jag specialist has changed the plugs (9600 miles) and also said there was clean fresh water in two wells. No oil. (Well a minimal amount).
So will have to just see if the fault codes come back.

Also reccomended to seal the plugs from getting wet again. Any advice on how to do this with pics if poss would be greatly appreciated.

 

I think you should have seals (aka boots) and one adds dielectric grease. Kinda wondering why the guy didn't know?

 

Jagv8 the guy ( jag specialist ) told me to use vaseline or something similar but he was busy sorting a leak in his roof at the workshop so couldnt speak to me for a lengthy period of time.

How do you suggest i do this having never done it before,? pull off the coils and smear the stuff over top of plug and up the side of the coil rubber boot?