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Discussion Starter · #1 ·
So i’m kind of confused on why my is300 is throwing these misfire codes after i’ve done a change recently i’d say about a few days ago or almost a week from today. I have an 02 is300, I got the NGK iridium ix plugs since i’ve heard on forums here that they are pretty good. I had an oil leak and I figured it was valve cover gaskets so I changed those and while changing them I decided to change my plugs also since I felt like it had been a while since i’ve changed them. Once I changed them I cleaned up the area of the spark plugs since there was some oil and a bit of other things i’d say as like oil build up and a few pieces of the coil connectors. Cleaned it and I changed all my coil connectors since they all decided to break when I was trying to unclip them. Nothing was inside the spark plug holes like any debris. Put everything back together carefully I took my time putting it all back together making sure each bolt was tightened and each sensor was clipped in the correct sensor. I also forgot to mention I cleaned the ignition coils also with some electronic cleaner. I started my car no codes everything ran fine it wasn’t rough idling or anything. Then recently got a code ran it this morning since I got off work and those codes popped up. I’ve looked through this forums to see what the issue might be i’ve done some research and cant figure it out. Otw home with those codes my car ran fine, it wasn’t idling rough or anything nor did I lose power in my engine either.


P.S. Also doing a timing belt/water pump change next weekend possibly and also changing the seals aroundthe area causing any oil leaks that are common in the is300.
 

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Discussion Starter · #3 ·
Check connectors again. Also do you know the coils are good? Did you have misfires before?
never had a misfire before ever, coils I haven’t changed them before since they were clean the last time i’ve changed plugs..but I will check the connectors in a few hours i’ll be sure to respond once I do check them again
 

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Discussion Starter · #4 ·
never had a misfire before ever, coils I haven’t changed them before since they were clean the last time i’ve changed plugs..but I will check the connectors in a few hours i’ll be sure to respond once I do check them again
Well I just checked and my connector
Check connectors again. Also do you know the coils are good? Did you have misfires before?
Just checked my connectors they seem to be fine nothing wrong with them or the wiring
 

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Discussion Starter · #6 ·
Well if they are seated good on connections and on the coils. Try to frog the coils. To see if the misfire moves with the coil.
my bad bro frogging the coils is a new lingo unless it means switch them around, If so I didn’t know you were able to do that, always thought it had to stay the way they were in originally.
 

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my bad bro frogging the coils is a new lingo unless it means switch them around, If so I didn’t know you were able to do that, always thought it had to stay the way they were in originally.
"Frogging" is a new one on me, too - but pretty sure he meant to swap. Our cars have 3 identical coilpacks; thus they are interchangeable.

So far you've not gotten misfire codes for cylinders 4 and 6 - so it seems somewhat logical to swap coils around to see if the misfire stays with the coil vs. the cylinder... However, because cyl 1 and 6 share a coil, as do 2/5 and 3/4 - I wouldn't expect coil swapping to help.

Ask 10 different people what the "best spark plug is" and you'll certainly get at least 9 different answers; and of course you'll find plenty of haters for each type too. Me? I like old fashioned cheap copper plugs. Only downside to them I've found is they only last 25-50k miles. Not directly applicable to IS300, but in the past, I've definitely found some ignition systems are rather sensitive to what plugs you choose (and wires, coils, igniters, etc).

Considering the only thing you really changed were plugs, my advice would be to try a new set of plugs. Also - because the Iridium plugs are so pricey, there are lots of counterfeits on the market; maybe you got a set of bogus ones...?
 

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Discussion Starter · #9 ·
"Frogging" is a new one on me, too - but pretty sure he meant to swap. Our cars have 3 identical coilpacks; thus they are interchangeable.

So far you've not gotten misfire codes for cylinders 4 and 6 - so it seems somewhat logical to swap coils around to see if the misfire stays with the coil vs. the cylinder... However, because cyl 1 and 6 share a coil, as do 2/5 and 3/4 - I wouldn't expect coil swapping to help.

Ask 10 different people what the "best spark plug is" and you'll certainly get at least 9 different answers; and of course you'll find plenty of haters for each type too. Me? I like old fashioned cheap copper plugs. Only downside to them I've found is they only last 25-50k miles. Not directly applicable to IS300, but in the past, I've definitely found some ignition systems are rather sensitive to what plugs you choose (and wires, coils, igniters, etc).

Considering the only thing you really changed were plugs, my advice would be to try a new set of plugs. Also - because the Iridium plugs are so pricey, there are lots of counterfeits on the market; maybe you got a set of bogus ones...?
Could be possible, i’ll try swapping the coil packs and see if it helps, if not I will try and swap the plugs out to see if there is ant differenc, I appreciate the help and advice 🤙🏽
 

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Discussion Starter · #10 ·
I guess I am getting pretty old. Never thought "Frogging" was not clear. You move the coil and wires to another coil and plug.
This is interesting, so I just got back home was going to change coil packs around to see if it’d do anything and if not buy new ones but had to pick up my dad at the dealer and CEL came on and went to check it when I got home (didn’t even get to change coil packs) and no misfire codes anymore but a set of new codes popped up.
P0130
P0133
P0150
P0153
I had the normal P0156 o2 sensor but that’s because i’ve decided to gut my cats out sadly bc I wasn’t going to spend 1200 on a new coverter if i’m moving to a different state with no emmisions so I could practically do wtv to my car in minnesota (currently here). But since i’ll be getting new headers/exhaust i’m going to do a o2 sim also when that happens

edit: Car runs perfectly fine still
 

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Discussion Starter · #12 ·
The primary O2 codes code be triggered by so many misfires. Or vice verse. As far as no cat code. You can try a spacer witch still will come back after a while. Or by a simulator.
hmm interesting, will be changing the coil packs asap whenever I can and i’ll see if there is any change or if it misfires on others i’ll get new coil packs and hopefully that helps, if neither work i’ll get new plugs
 
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