[f10m5]

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

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

 

[Forced_Induction]

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

 

[Forced_Induction]

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

 

[Forced_Induction]

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

 

[Forced_Induction]

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

Literally Same exact codes I get , with exception of once in a blue I’ll get something about a cold injector or something I can’t remember off top of my head ,

 

[f10m5]

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.

 

[Forced_Induction]

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

 

[Forced_Induction]

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

ived never had any idle issues , when its misfiring ill smell a bunch of fuel itll sound like its camm'ed thats how i know its misfiring, but as sona s i turn it off and back on its gone or clear code its gone.
once thing i did notice that's strange is at idle ill get like a momentary shake like real quick i dunno if I'm explaining it right. but its the weirdest thing like its just like a hiccup it'll happen like once in a blue moon almost like something i.e ac clutch engage or something and itll do a quick shake but then normal after

 

[rm2]

OK so I searched the forum and found only one thread about this
a friend alsked me to help him with his car he's having a random misfire on cold startup cylinders 5,6,7..
here's the weird part, if I restart the car or clear the codes it runs fine. like nothing happened
but without fail every morning or if the car sits for a period of time when he starts it check engine light blinks and its like the car automaitaclly its fuel to those same cylinders. but the ill turn it off and on and works fine.

so far I've changed plugs, wires, all coils, and the cats.
, timing seems fine . Compression's fine not the HG
I don't think( THINK) lol I could be wrong but I don't think it's anything mechanical as if I restart it everything runs fine. he's restarted it and drove the car over 200 miles no issue but wparked it and next day same thing

Next on my list is the injectors, could this cause this issue?
has anyone ever had anything like this?
I commented on another post where a guy had the same issue saying something about reprogramming the eco fixed it

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

 

[rm2]

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.

Hopping on. Have a 5.0 SC L405 with same cold start misfires. It almost has to be computer vs. mechanical issue. Mine will consistently misfire on cold start between 40-50sec almost exactly then lower down to smooth idle. I found a service bulletin on ALLDATA and took it to the LR dealer requesting the update. They just recommended BG injection service but did not perform the update. Basically ignored that request. I've driven around 15k miles with no changes. Did perform new plugs, coils, BG injection restore twice. (process takes about an hour). I have an Autel programmer and was able to refresh the pcm but still no changes. Ive learned to live with it but there has to be a solution...

 

[Forced_Induction]

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

 

[Bird88]

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

 

[Forced_Induction]

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?

 

[f10m5]

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.

 

[GeorgeBuhr]

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.

 

[Forced_Induction]

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.

 

[GeorgeBuhr]

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.

 

[Forced_Induction]

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