2015 LR4 Throwing Misfire Codes. Need some help...

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Daveykid

Supporting Member
Supporting Member
Joined
Jan 14, 2022
Posts
106
Reaction score
25
Location
Chicago
First post here guys (and gals) so be kind. :) Not new to forums, just this one.

I have a 2015 LR4 HSE Lux, 68K miles, that is throwing misfire codes. Saturday morning was around 18F degrees here in Chicago and it happened on the cold start only. Once the engine warmed up not more than a minute, I was able to clear the codes with a basic scan tool I have. After that it was fine the rest of the day...even with the car sitting for hours before restarts. Unfortunately my scan tool doesn't allow me to go too in-depth. (Yes, I ordered an IID scan tool but it won't be here for a while yet.).

Codes are P0300, P0302 and P0303 on Saturday and on Sunday morning add P0301 to those as well (and 22F degrees). (Screen shots attached.) Seems to me one entire bank. Again, they clear with my current scan tool and don't come back but I'm beginning to see a pattern here with the temps perhaps. Other cold start days haven't affected it up to this point, which leads me to my next point.

So, what have I had done to it recently? Had the passenger side valve cover resealed for seepage/leak by what I thought was a competent mechanic and don't know if the two are related or not based on the fact that he probably had to disconnect quite a few vacuum lines and maybe even the spark plug wires to get to it. At this point all I'm looking for are some obvious possibilities I can fiddle with before I go back to the mechanic and ask him to have another look at it. I'm decently competent under the bonnet but if it's beyond my skill level pay grade I'd at least like to go into it with him with some confidence knowing what it *might* be. TIA!

Saturday.jpegSunday.jpeg
 

jlglr4

Full Access Member
Joined
Mar 19, 2019
Posts
932
Reaction score
477
Location
Northern California
How long ago was the valve cover leak repaired? If it was just done, I probably wouldn’t fiddle with much before taking it back to them or they might blame the problem on your fiddling.

Removing the valve cover requires removing the fuel rail and injectors. I believe the injector seals must be replaced before reinstalling, or they can leak. So, that’s a possibility - tends to be worse after sitting overnight because fuel is pooled up in the cylinders. Could also have a leak at a fuel line junction, which could give you low rail pressure leading to misfires.
 

Daveykid

Supporting Member
Supporting Member
Joined
Jan 14, 2022
Posts
106
Reaction score
25
Location
Chicago
How long ago was the valve cover leak repaired? If it was just done, I probably wouldn’t fiddle with much before taking it back to them or they might blame the problem on your fiddling.

Removing the valve cover requires removing the fuel rail and injectors. I believe the injector seals must be replaced before reinstalling, or they can leak. So, that’s a possibility - tends to be worse after sitting overnight because fuel is pooled up in the cylinders. Could also have a leak at a fuel line junction, which could give you low rail pressure leading to misfires.
It was just done this past Thursday so yeah, I definitely won't monkey with it. Is cylinder 1, 2 and 3 on the passenger side because that's the side they worked on.
 

jlglr4

Full Access Member
Joined
Mar 19, 2019
Posts
932
Reaction score
477
Location
Northern California
Yes, according to my manual, 1, 2, and 3 are passenger side. The 5.0 V8 used the more conventional even-odd numbering for the two banks, but they apparently switched it up to consecutive numbering on the scv6.

Good luck with it and please report back to let us know what you find out.
 

puckball55

Member
Joined
Jan 11, 2022
Posts
22
Reaction score
7
Location
south florida
How long ago was the valve cover leak repaired? If it was just done, I probably wouldn’t fiddle with much before taking it back to them or they might blame the problem on your fiddling.

Removing the valve cover requires removing the fuel rail and injectors. I believe the injector seals must be replaced before reinstalling, or they can leak. So, that’s a possibility - tends to be worse after sitting overnight because fuel is pooled up in the cylinders. Could also have a leak at a fuel line junction, which could give you low rail pressure leading to misfires.
great info , taking my 2013 in mon for valve cover gaskets
 

Latest posts

Members online

No members online now.

Forum statistics

Threads
36,222
Posts
217,567
Members
30,473
Latest member
OnoA
Top