P38A Misfire after oil change - 4.0 Thor / Bosch

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domlinson

Member
Posts
61
Location
Essex
Hi all,

As the title says, I changed the oil and oil filter yesterday and have now developed a misfire...

I've got a P1319 code as a current fault which I believe is something like "Misfire detected at low fuel level" - the fuel level isn't low.

I changed the spark plugs and air filter about 300 miles ago, and it's been running great up until yesterday.

I had all the plugs out today and they all appear to be burning the same, with the exception of cylinder #1 which appeared to be slightly 'wet' with what I think was fuel.

Popped all the plugs back in and went for a spirited drive to see if it would clear but the miss is still there..

I've got new plug leads on the way as they're cheap enough to eliminate those as an issue.

Anyone have any theories as to why this started happening after I did an oil change? I'm guessing it's a coincidence, but you never know!

Thanks
 
I've had this error code, does it pop under hard acceleration?
mine was down to the cams being worn. specifically in my case, one of the exhaust valves wasnt opening and gases were released back into the intake when that valve opened :eek:
everything else was fine and the code went away with a new camshaft
 
kermit_rr said:
I've had this error code, does it pop under hard acceleration?
mine was down to the cams being worn. specifically in my case, one of the exhaust valves wasnt opening and gases were released back into the intake when that valve opened :eek:
everything else was fine and the code went away with a new camshaft
Click to expand...

There's no popping under hard acceleration at all, and I did really 'give it some' to try and let it clear it's throat...
 
thats good, worth doing a compression test, though that came up fine for me as the valves were sealing properly.
the reason for the misfire in my case was because the exhaust gas had no where to go, eventually it got sooted up and nasty
i wonder what happens if you have an inlet go, instead on an exhaust? lets see, inlet doesn't open, no fresh oxygen rich air, fuel doesnt burn properly, ends up with a sooty, wet plug, just a thought
 
kermit_rr said:
thats good, worth doing a compression test, though that came up fine for me as the valves were sealing properly.
the reason for the misfire in my case was because the exhaust gas had no where to go, eventually it got sooted up and nasty
i wonder what happens if you have an inlet go, instead on an exhaust? lets see, inlet doesn't open, no fresh oxygen rich air, fuel doesnt burn properly, ends up with a sooty, wet plug, just a thought
Click to expand...

I'll do a compression test later just in case that highlights anything obvious..

kermit_rr said:
do you have a nanocom or similar to read rough running values?
Click to expand...

Unfortunately not - just a generic scanner, which luckily plays nicely with the Bosch motronic for reading fault codes... but is obviously more limited than a proper RR diagnostic like the nanocom..

I can read live values from the motronic though, do you know what values I should be looking for?
 
i have torque pro which does some live engine data, you dont get rough running values though. you might see if there are misfires though
I had 1319 for quite a while before i noticed any symptoms
 
kermit_rr said:
i have torque pro which does some live engine data, you dont get rough running values though. you might see if there are misfires though
I had 1319 for quite a while before i noticed any symptoms
Click to expand...

Ah ok, Torque Pro is what I'm using too.. I'll go and plug it back in to see if I can see anything relating to misfires in the live data.

I've had it plugged in a few times in the past few weeks, and this morning is the first time i've ever seen a P1319.

I'm still struggling to understand if my oil change could have triggered this issue, or if it's purely a coincidence...

One thing I've just remembered; when I changed the spark plugs I noticed that one of the plug leads is split at the boot, however it had been running fine and continued to run fine, but it obviously needs to be replaced, however this is on cylinder 2, not 1 (the one with the wet plug)...
 
as far as i can understand, 1319 is basically... we detected a misfire, but the coil, injector and MAF values are within range so you must be low on fuel
if your plug lead is leaking then perhaps that could cause 1319, i dont know
 
I think I need to go and do the lottery...

I just went out and plugged my OBD scanner back in, and also took my infrared thermometer out there to see if it was definitely #1 that was down, and it was... couldn't see any useful data in Torque, so thought I'd chase the plug lead back to the coil to make sure everything was OK back there.

IT WAS UNPLUGGED

I do not understand how it became unplugged, especially as an oil change doesn't go anywhere near that area, but it did... i'm now back on all 8.

I think this is a lesson in checking the simple stuff first!

Thanks again.
 
kermit_rr said:
glad you're fixed! i'm surprised you didnt get a misfire code for that cylinder and only a generic one
Click to expand...

Thanks! Me too, when I googled for the P1319 code everything seems to indicate that it probably isn't ignition related because it's the generic code not cylinder specific... However in my experience that is not the case haha.
 
Quick update for anyone interested... Replaced the leads this morning. I now understand how plug #1 was disconnected... The leads on my engine clearly haven't been changed in quite a while, and they pretty much all fell off of the coils without any persuasion.

The new leads that I purchased from JGS4x4 from here have a different design and click in much more affirmatively than the old ones did.

Also, the engine now runs better than it ever has for me, so much smoother. I think I've been dealing with intermittent misfires without realising (this is my first V8, so I just assumed it would be 'rumbly' in comparison to all the straight six's that i've been used to previously).
 
domlinson said:
Quick update for anyone interested... Replaced the leads this morning. I now understand how plug #1 was disconnected... The leads on my engine clearly haven't been changed in quite a while, and they pretty much all fell off of the coils without any persuasion.

The new leads that I purchased from JGS4x4 from here have a different design and click in much more affirmatively than the old ones did.

Also, the engine now runs better than it ever has for me, so much smoother. I think I've been dealing with intermittent misfires without realising (this is my first V8, so I just assumed it would be 'rumbly' in comparison to all the straight six's that i've been used to previously).
Click to expand...
Had same problem with the V8 in a SD1 Rover
 
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