Hi have you checked the batteries? There's 2.

 

Both new

 

I literally joined because I saw this post and I've been having the same identical issue for about a year. I did recently see someone mention having a similar problem and they replaced front 02 sensors and it solved it, however I haven't tried that yet. I changed coils as well as plugs with no change. My thought previously was maybe leaking injectors but I'm not convinced that's it.

 

Man this **** had me stumped lol, I have a set of injectors I’m gonna try and swap them out this week , one my guys at my boys shop swears it’s that . I honestly can’t put my finger on it , it’s so weird that restarting the car fixes it … I changed the 2 rear o2 sensors when I did the cats . Never tried the fronts . I was sure it was the cats with the blinking light on start saying that means I burnt fuel getting in cats and high temp can cause damage . So it cuts the fuel . I guess maybe leaky injector could do that as well but why would it just run normal after restarting …
Let me see if I can find the post where I saw a guy saying he had the dealer reprogram the Ecu and that fixed the problem

 

Any update have the same issue on my l405 5.0

 

I got a set of injectors from a friend who popped his motor and a set of 2 new boSch 02 sensors , I’m gonna try and fit them this weekend if weather permits and see if that works hang tight guys I’ll keep you posted , last thing I can think is a vacuum leak I can def head something coming from, that’s rats nest under the manifold I’ll try and sort that out too

 

Fingers crossed it works, please keep us updated

 

Just gonna throw my .02 cents in which isn't worth squat, but I heard you say you had a misfire on 5,6,and 7. What were the codes that it kicked off. Just misfire codes? I think it can be assumed to a certain extent it is not a head gasket, because you have misfires on both sides of the engine. I could see one side or the other going out, but not both unless it got hot enough to destroy both sides. I think it is important to get some data to look at when this occurs. It very well could be injectors that are dirty. I would like to know :

• fuel pressure. If you don't have proper fuel pressure, fuel cannot be atomized correctly, and it is particularly important on these motors because of the high pressure needed. Poor fuel pressure could mean a weak high or low pressure fuel pump, which could definitely cause misfires all over and can also if left unfixed will destroy the cats.
• fuel trim numbers. depending on how the numbers look, it could show ecu is compensating for weak fuel pump, OR a leak in the air intake track, either of which could cause a lean condition and random misfires.

It seems likely its fuel related; clearing codes makes it run good which means its getting good spark, but if it is sucking air or on low fuel pressure, ecu is compensating and changing long term fuel trims to counteract whatever the problem is. Just a theory, but its nice to know if numbers look off before you start swapping parts.

 

I only get the misfire codes and persistent damage to cat or whatever no other codes , but the lights don’t stay it flashes during cold start then goes away .

I agree with fuel part but part that baffles me is if I literally turn the car off and back on it’s like nothing happened . If it was something mechanical that was no good ie fuel pressure pump injector why would it just start working after a clear or restart .
i turned car off on and did a 3 hour round trip drive not a single hiccup in the truck

 

If there's a small leak in any part of the pressurized fuel system it can lose pressure overnight and cause misfires upon initial start-up. Try pushing the start button without having your foot on the brake, the thought being to activate the fuel pump and pressurize the system. Do this for a few seconds then start it and see if that made a difference.

 

I been so busy finally got to pull it apart I these are my old injectors one looks a little hurt , I am gonna try and find somewhere to flow test the next set I got before I put them back n

 

I'm curious if injectors made a differences? I've always wondered if it's just a leaking injector

 

You want a good laugh bought brand new set Bosch injectors put them in and 2 of the injectors were stuck open had to pull them out put my stock ones back in , had to send them back get a another new set and all that and after all that it still didn’t change anything . Im Convinced it’s either the ecu or like another guy said maybe a small leak somewhere in fuel system, that when you start it after sitting pressure isn’t up but by turning it on it builds pressure back up and hence fixes the issue

 

You want a good laugh bought brand new set Bosch injectors put them in and 2 of the injectors were stuck open had to pull them out put my stock ones back in , had to send them back get a another new set and all that and after all that it still didn’t change anything . Im Convinced it’s either the ecu or like another guy said maybe a small leak somewhere in fuel system, that when you start it after sitting pressure isn’t up but by turning it on it builds pressure back up and hence fixes the issue

I’ve literally changed everything else , a friend blew his motor with like 40k miles on his 2021 we swapped superchargers and **** near all the parts I could get off it before giving it back to insurance lol still no dice

 

Any update? 10k miles of doing this since last fall. I’ve learned to live with it.

Every cold start misfires bad always a few cylinders 5,6,7,8. After restart it’s like nothing happened.

I’ve gotten some weird codes aside from the typical cylinder misfire, persistent cat damage. One is cold start injection performance. The other one slips my mind. I had done research on the codes and there was absolutely zero information on them.

Hopefully in the next few weeks I’ll throw some new injectors in. Might try some injector cleaner for fun.

 

man I can’t call it , I’ve changed injectors , cats , injector cleaner , all that still doing it , . I’ve done the same u have my gap plugged in I just clear codes and drive on a cold start . Someone had mentioned changing the ecu I didn’t try that

 

I have heard someone say to reflash the ecu but I havent tried that personally. My l405 is absolutely the worst vehicle ive ever owned so at this point ive just stopped caring honestly.

 

Honestly I just stop stressing it lol , at first I was literally determined to figure it out now I’m just like **** it lol it runs fantastic outside of this crap. There’s a range specialist I was suooosied to swing by him honesty I just haven’t even made it a priority(He was the one who mentioned maybe ecu) . I drove it the other day about 200 miles round trip not even a hiccup . Next day went to start it same misfire lol

 

I thought I replied yesterday I guess didn’t go through. Do you have the erratic idle ?

The code of cold injector is cold start injection performanceNobody knows a clue about this code. Here I have it attached and get it too. Zero info anywhere in the world on it. At least the internet.

I was expecting the injectors to be the smoking gun nut after what you have gone through I’m gonna save the money and time. And mine are only two years old. They were replaced in summer 23 when I did the first timing job. Last summer I had to do it again since JLR dealer lied to me and only did one tensioner. This issue started after the second timing repair which was more involved with new valves and resurfaced head. I had bank two completely rebuilt. At this point my L405 is at 200k miles. Should have stopped last summer and thrown in the towel before timing job #2 but have too much sentimental and emotional value in this truck.

I am convinced this is a ECU issue.

 

Maybe im just tryna talk myself out of it but there's another 2 guys i know that have the same issue and the only thing we all have in common was a motor rebuild/timing lol. that's the only part that scares me lol.i dunno how far you got into the rebuild but i got pretty deep, cutting heads and block new pretty much everything pistons rods valves etc. I'm still leaning towards the ECU because it has to be electrical I've literally changed every other mechanical part minus the ECU... Injectors, plugs, coil packs, cats, I just don't want to go to the dealer lol I'm gonna try and do some research on how i can get an ecu reprogrammed.
there has to be someone on the forum with some insight on this.
I'm, far too invested in this **** truck to give up lol. when i rebuilt the motor i ported the head / super charger, got the pulley all that other crap, so i hate to just give up.
Like is aid once u restart or clear codes it runs like a freight train. so i find it hard to believe its anything mechanically wrong

 

Is your guys idle erratic slightly after the initial cold start misfire?? I’ve noticed and this happens even after hours of driving the idle is erratic +- 30-40 RPM ALWAYS.

For example I am sitting in my truck after a hour and half stop go NYC traffic and RPM will jump from 590 to 630 to 610 to 580 constantly moving. You can’t really feel it unless your stopped. It’s very small you won’t even see needle rise but since I have the gap tool plugged in it shows the actual reading of RPM jumping around.

I can also slightly feel it in reverse.

Attached are the fault codes. Someone told me both banks are misfiring but I thought bank 2 is 5-6-7-8?

Also I heard about flashing a new PCM. I think that’s what you guys mean not new ECU

 

Guys super random question i was just thinking about it the other day, of all the guys with the issue are you on the original thermostat? or aftermarket? i have one of those afterma4rket aluminum thermostat housings, i wonder if that could cause the issue? i think i even had a plug on the thermostat that i didn't use and it always bothered me .
I was on amazon the other day and the thermostats kept popping up and i was opening them and reading the reviews and like 5 people like don't use this as soon as i installed it i got random misfire's lol

 

I had the origional thermostat in when it started I have a new one in now. So for me definitely isnt it.

 

lol i randomly get motivated to mess around with this POS lol i have a set of new 02 sensors i may throw them in this weekend, i only changed the 2 back ones i think I'm gonna change the 2 front ones and see what happens, that's the only persistent thing i do notice. i get random o2 sensor codes while driving , Have you changed out all 4?

 

The guys that build my engine had a falling out apparently over my truck. Reguardless the main guy had me come over to his new shop for a oil change where I wanted to discuss the cold start misfire.

He’s convinced it’s my bank 2 cat converter. I am 99.9% sure that’s not it. My bank 2 cat has been failing for about 4 years. It started with the efficiency code coming on here and there and slowly progressed to now always being on. The reason my cat failed im pretty sure is because I am tuned. I have been tuned for over 6 years with Velocity AP “SVR burble” tune. One of the downsides of the burble tune was premature catalytic convertor damage. I have zero O2 codes never had a single one.

If I can find a cheap cat or a used cat I’ll throw it in there but I’m in no rush. I know that’s not going to fix it. I am inclined to just live with this issue because the guy was telling me he’d open up the engine and recheck it all if the cat doesn’t fix it. I’m not keen on having it tore down again….

Im over 200k miles. This truck is now a beater. Ill be sending my oil over to black stone for some analysis.

 

Well, there is one really quick way to check. Disconnect the exhaust at the header and fire it up cold. If it still misfires, its not the cat.

 

Ok so random I got fed up with messing around with the truck and took it to a local guy who specializes in land rovers , and left it with hi for 2 weeks and go figure knock on wood th3 misfire finally stopped , he claims he just changed. A a coil , an injector, and set of plugs and did a leak down test just for my peace of mind on compression .

im Still getting the cat codes but I knew that was bad but the misfires finally gone after a while **** year of buying parts and changing them smfh . I’ll take a pic of my receipt , he charged me 1200 total and says he changed an injector , a coil and a set of plugs and “diagnostic” lol

honestly I think it was electrical and he just maybe doesn’t wanna say I popped in on him once and he had it hooked up to a computer doing something . What he says just doesn’t make sense I changed all my plugs 2x / all my coils / injectors all of that.

 

Thanks for the update. There is always the chance you buy a new part and its bad out of the box, but you may be right that it might have had a bad connection on one of the wires. For the cat codes, you might try running some cataclean through it a couple times and see if they go away.

 

only thing he said was he didnt like the parts i put in , i thought i was using OEM stuff i used NGK plugs and Delphi coils , and Bosch injectors..
Im still convinced its soemthing electrical he did. if it was a mechanical part it wouldn't just randomly work perfectly fine when i restart the car.

I've seen a cool 10 or more people on the forum with the same issue and they just drive it.. im surprised this hasn't come up with JLR