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Looks like bank 1 is going lean on you, bank 2 looks fine. If this was a fuel pressure issue both would be going lean. For it to be so specific to cylinder 6, an exhaust leak would be close to the head. I'm not sure how obvious it would be to find a leak in the manifold through the engine bay unless you have broken manifold bolts. I would go ahead and do the header swap and see what you find. An exhaust leak is kind of moot if you are changing exhaust anyway.
Looks like bank 1 is going lean on you, bank 2 looks fine. If this was a fuel pressure issue both would be going lean. For it to be so specific to cylinder 6, an exhaust leak would be close to the head. I'm not sure how obvious it would be to find a leak in the manifold through the engine bay unless you have broken manifold bolts. I would go ahead and do the header swap and see what you find. An exhaust leak is kind of moot if you are changing exhaust anyway.
thanks for pointing out, didn’t even notice bank 1 leaned out like that. But this is long term fuel trims on idle seems bank 2 is lean and bank 1 is fine
Yours appears to be hitting 11.9:1 AFR which is what mine does when fueling at WOT but my B1 B2 fuel trims mirror each other 99% of time. And at steady cruise, the LTFT zero out.
IMO the 4th gear load creates the most work and work being cylinder pressure loading is subject to ignition failure.
Are those Denso Plugs and Coil Packs? If not, I would start there as it's getting fuel based on your data. I was simply too lazy to go look it up.
Only use the AFR data on the left next to the value.
Originally Posted by MikeFig82
After reading you having Ruthenium spark plugs installed. I remember reading about them on the ISF forum. After that I never purchased them from RockAuto since they were new at the time, and stuck with the Iridiums TT.
WOw I forgot about that thread, I remember seeing it when I was doing research on what plugs to get. u just reminded me about that thread thanks lol cuz that's basically what I'm experiencing at high rpm, but the thing is after swapping the coils and sparks, the misfires still happening in the same cylinders. I'm going to clean my old sparks and put them back in if this gasket doesn't do anything.
After reading that thread Mike posted, and having seen this during my stand up jet ski racing, the wrong plug will screw you over under certain circumstances.
Denso Denso Denso. Coil packs and plugs! Why it repeats on those cylinders, likely extra blowby, intake leak going lean, something is different creating a misfire.
Just asking. So with the Intake did you replace the rubber gaskets from the plastic top to the metal bottom also? Also did you do the porting yourself? Any chance you removed some materials from the base of the Intakes where they seal?
After reading that thread Mike posted, and having seen this during my stand up jet ski racing, the wrong plug will screw you over under certain circumstances.
Denso Denso Denso. Coil packs and plugs! Why it repeats on those cylinders, likely extra blowby, intake leak going lean, something is different creating a misfire.
Change them!
Good find Mike!
FFFIIINNNEEE ILL CHANGE THE SPARK PLUGS BACK TO THE DENSOS I HAD IN BEFORE. and I did the vacuum leak test and there's a leak near cylinder 6 but deep in there and I cannot see it while it's in the engine bay, so ima makeshift some sort of test bench for the manifolds. I'm thinking the damn sparks might be the issue since I have almost the exact same symptoms as the guy with the ISF. I pray that's the issue so I can just go back to modding lol
Just asking. So with the Intake did you replace the rubber gaskets from the plastic top to the metal bottom also? Also did you do the porting yourself? Any chance you removed some materials from the base of the Intakes where they seal?
I only replaced the rubber gasket, I've been told by many that the metal one usually don't need changing, but I might change it after I do my tests. I got them ported by @triggaspec on Instagram, I've had them for months with no issues and it seems like he did a good job. I'll send pics of the runners next time I molest my car.
After putting back OEM Spark plugs, same thing. I did some research and have seen people with similar issues and it was either their ignition coils, or in-tank fuel pump. Honestly might as well just do both at this point since I'm at 200k already. Here is a video of it while its actively happening, it lacks the power to climb the rpms to redline.
Also @jgscott, remember u were being a major butthead when I was asking if this guy had any performance results of his ported manifolds he was selling on here then we both got removed from the thread lol
I thought you found a leak from your intake manifold, have you addressed that yet?
Haven't fully checked it out yet, still need to get some sort of slab and the correct drill and taps to do the job. But in the meantime I'm gonna do a mechanics special and throw some parts at it, coils and a fuel pump. I'll also admit, I was told 180k was the interval to change the coils and I've been edging it 20k miles past due.
Haven't fully checked it out yet, still need to get some sort of slab and the correct drill and taps to do the job. But in the meantime I'm gonna do a mechanics special and throw some parts at it, coils and a fuel pump. I'll also admit, I was told 180k was the interval to change the coils and I've been edging it 20k miles past due.
hey me too. I’m at 194k miles and past due in my 2008 is250.
New coils. Same thing, if anything the pinging sounds a bit worse now
Originally Posted by Idkyet2is
Also @jgscott, remember u were being a major butthead when I was asking if this guy had any performance results of his ported manifolds he was selling on here then we both got removed from the thread lol
Full Disclosure here.
So you were posting in a members for sale section that was advertising his ported upper/lower intake manifold for sale. The Member felt you kept trolling him every ad he posted 2x's. You were telling him he needed to install them then draggy test, and dyno and post the results. FYI: He sold the GS350, and bought a GS F so did not even have the 350 anymore. Weird is, you have the ported Intakes yourself so you have the ability to do it yourself and test now we see. That really was messing up someone's classified ad who was trying to sell something they had. You were telling him he needed to do the test for you. lol!
You also have too many things wrong to start like Cat codes, oil burning and other to start doing performance mods. You need to fix the problems 1st before you start. It looks strange that you making all these changes and the cars engine is not running right from even the start before you put on the mods. Personally before I went spending large amounts of money on mods, I would have spent the money to get my base engine problems corrected 1st. But that's just saying.
Originally Posted by DickH
I thought you found a leak from your intake manifold, have you addressed that yet?
Seems that he has not and this is likely his problem. The metal gaskets are crushed, and leaking, that's why I asked him if he had used new rubber gaskets and metal. I also think there could be a machining problem on the ported intakes that may not be a even plane for the mating surfaces.
07-22-23, 01:09 AM
