8th Gen Si misfires

AdamD19DFK8

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Hi all, not sure if this would be the proper place to ask this, but my old backup beater, a 2007 Civic Si has been having misfire code issues for awhile. Random cylinder misfires and misfire codes on each individual cylinder. It's got 205k miles on it, so It could have any number of underlying issues. Ive already taken the liberty to replace the spark plugs and coil packs but the issue still persists. Driving the car it seems to drive fine. Though I don't have a good perspective of what it's power should feel like anymore since i've gotten really used to having ~400 ft/lbs of torque.

I've data logged some drives and nothing really sticks out to me, other than the ECU targeting an AFR of ~11.1:1 with the engine actually receiving anywhere from 13.5-14.7. I don't know whether to pull off the intake manifold and exhaust manifold/cat to see if the cat is bad or if cleaning the intake manifold out would do the trick. It could be possible a fuel injector could be bad, I looked at them without pulling them and there were no leaks at least.

I know this is a common problem with this car and was hoping someone had experience in narrowing down the issue.

Thanks
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Arashishozen

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Hi all, not sure if this would be the proper place to ask this, but my old backup beater, a 2007 Civic Si has been having misfire code issues for awhile. Random cylinder misfires and misfire codes on each individual cylinder. It's got 205k miles on it, so It could have any number of underlying issues. Ive already taken the liberty to replace the spark plugs and coil packs but the issue still persists. Driving the car it seems to drive fine. Though I don't have a good perspective of what it's power should feel like anymore since i've gotten really used to having ~400 ft/lbs of torque.

I've data logged some drives and nothing really sticks out to me, other than the ECU targeting an AFR of ~11.1:1 with the engine actually receiving anywhere from 13.5-14.7. I don't know whether to pull off the intake manifold and exhaust manifold/cat to see if the cat is bad or if cleaning the intake manifold out would do the trick. It could be possible a fuel injector could be bad, I looked at them without pulling them and there were no leaks at least.

I know this is a common problem with this car and was hoping someone had experience in narrowing down the issue.

Thanks

205k miles, Misfire on all cylinders, and a misleading AFR?
If I was a betting man, I'd say your timing chain stretched a bit and jumped a tooth. You can be one tooth off and cause those issues. Esp since you already replaced Coil and plugs.

I'd check timing, and check the timing tensioner to see if it is in spec.
 

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Would also check your short term fuel trims during idle to see if anything seems out of ordinary. I had a J Series V6 accord and had intermittent P0300 random cylinder misfires, and it was really frustrating to find what the root cause was. Eg. a ripped intake snorkel caused a huge vacuum leak and a lean condition. Also, yes to above post, verify if timing is off? Were valves adjusted at your current mileage?
 
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AdamD19DFK8

AdamD19DFK8

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205k miles, Misfire on all cylinders, and a misleading AFR?
If I was a betting man, I'd say your timing chain stretched a bit and jumped a tooth. You can be one tooth off and cause those issues. Esp since you already replaced Coil and plugs.

I'd check timing, and check the timing tensioner to see if it is in spec.
Over the winter/spring I pulled the engine and did a full engine rebuild. Bore/honed the block for JE forged pistons, Skunk2 alpha rods. Resurfaced and rebuilt the head with Manley dual valve springs, new valve guides, seals, and valves. I spent hours lashing the valves multiple times to ensure I had the same clearances across the board. Setting the timing was probably one of the easiest parts of the build.

Did a full refresh on seals and gaskets, timing chains and tensioners, water pump, auto tensioner and idler pulley. Basically replaced anything that was worn.

I need to sell my flashpro from the Type R so I can get a tuner meant for the FA5 as the Type R one won't work and doesn't data log much info at all.

After everything was back together and I got the car back on the road the CEL popped back up.
I still need to get a spark plug gap tool to get those in to spec, they're a little tight.
 


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Over the winter/spring I pulled the engine and did a full engine rebuild. Bore/honed the block for JE forged pistons, Skunk2 alpha rods. Resurfaced and rebuilt the head with Manley dual valve springs, new valve guides, seals, and valves. I spent hours lashing the valves multiple times to ensure I had the same clearances across the board. Setting the timing was probably one of the easiest parts of the build.

Did a full refresh on seals and gaskets, timing chains and tensioners, water pump, auto tensioner and idler pulley. Basically replaced anything that was worn.

I need to sell my flashpro from the Type R so I can get a tuner meant for the FA5 as the Type R one won't work and doesn't data log much info at all.

After everything was back together and I got the car back on the road the CEL popped back up.
I still need to get a spark plug gap tool to get those in to spec, they're a little tight.
So you didn't have any problems till you did the engine rebuild? Did you change the VTC actuator?
 

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Maybe fuel pump or fuel filter aint providing the flow? you said it is every cylinder, so maybe it’s a fuel issue.

Tank of bad gas possibly?
 
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AdamD19DFK8

AdamD19DFK8

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So you didn't have any problems till you did the engine rebuild? Did you change the VTC actuator?
I had the random misfires before the rebuild. I mainly did a rebuild because of the mileage and to be able to run big power from a turbo.

I didn't change the VTC actuator on the cam. The valvetrain looked immaculate on teardown other than the valves and valve guides. Had bad oil consumption issues before but could easily tell the valve guides were out of spec once I got in there and could wiggle the valve stems inside easily.

I've been driving it pretty lightly since it's got a new clutch plus seating the new piston rings. I've revved past 6k while driving just to make sure VTEC still crossed over, which it did fine, and pulled better than it was before.

Maybe fuel pump or fuel filter aint providing the flow? you said it is every cylinder, so maybe it’s a fuel issue.

Tank of bad gas possibly?
I'm thinking it's a fuel issue as well. I had gas sitting in there for over a year, but I burned most of it up when burping the coolant and just letting it run out, refilled it with 93

Or possibly a vaccum issue from the intake. I wanted to run the stock intake again on it to rule that out, but I can't find the metal fitting that goes to the breather port on the valve cover which the aftermarket intake I have eliminates, so I had to run that.

Eventually I'll need to get new injectors and will upgrade the in-tank pump for boost, maybe it would be worth going into the tank now to check the filter.

Driveability wise I can't tell that anythings wrong or out of the ordinary. It's driving better than it was before. Idle seems normal as well. I put in the Hasport 70a motor mount set which is worlds stiffer than the beat stock motor mounts that were in there so they add a bit of vibration. I also did a full a/c system rebuild after not having air conditioning for like 6-7 years. Sitting while idle with the a/c compressor running it get's pretty vibratey in there but thats mainly from the motor mounts.

I really need a flashpro meant for the FA5 so I can disable codes so it will hopefully pass emissions. That's what I'm mainly worried about. I had an emissions test due around the time I cancelled my insurance and turned in the tags. Hopefully I have a bit until they send me another emission notice after re-tagging it this week.
 
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tacocat

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I had the random misfires before the rebuild. I mainly did a rebuild because of the mileage and to be able to run big power from a turbo.

I didn't change the VTC actuator on the cam. The valvetrain looked immaculate on teardown other than the valves and valve guides. Had bad oil consumption issues before but could easily tell the valve guides were out of spec once I got in there and could wiggle the valve stems inside easily.
Those engines are notorious for oil consumption which starves the VTC actuator and can cause it to not phase correctly and a misfire code. Accords/CRV's/Civic si's all had that, it was a huge problem. Not saying that's it but could be something to look at with 200k miles on it.
 

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If you can, do a crank pattern clear and a crank pattern relearn. After doing all that stuff, it might have messed up what the computer thinks is happening, resulting in false misfires.

I say false misfires bc if it runs well but has a misfire, doesn't sound like it actually has one.
 


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AdamD19DFK8

AdamD19DFK8

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Those engines are notorious for oil consumption which starves the VTC actuator and can cause it to not phase correctly and a misfire code. Accords/CRV's/Civic si's all had that, it was a huge problem. Not saying that's it but could be something to look at with 200k miles on it.
Yeah I replaced all of the valve guides to combat that, plus brand new valves.
I had a machine shop bead blast and resurface the head as well as install the valve guides and seat valves. They bored/honed the block as well but I did everything else with the motor.

Checking main bearing and rod bearing clearances was a major PITA. Luckily all of my main journals were in spec leaning on the looser side. Used ACL race bearings and didn't have to mix and match to make them work. What's the saying "Too loose, only you'll know...too tight everyone will know" lol

The timing chain rebuild kit I got came with the exhaust cam gear only. I plan to upgrade the cams down the road where I'll get a new VTC actuator, right now I don't have the money for anything, I need to sell all of my Type R parts seeing as how I don't have it anymore since someone murdered it at a stop sign. :( It's been a shitty year
 
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AdamD19DFK8

AdamD19DFK8

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I went ahead and ordered a new VTC actuator from Japan and it came pretty quickly luckily. The car does seem pretty lacking in the very low rpms, but then again it's an NA engine with barely any power. My cat heat shield is rusted to hell I need to remove it. From ~1k to around 3 to 3.5k it rattles obnoxiously.

Atleast when I remove the shield I'll be able to tell if the VTC actuator does that rattle it's known to do when it needs to be replaced, i'm uncertain if I hear it or not since the shield rattles.

Good thing the VTC actuator can be replaced without having to remove the timing cover, I was kinda worried about that since I had to fight the Hasport mount on that side hard to get it on. Basically beating on it and tightening one of the motor mount nuts down on it.
 

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I remember putting a custom CAI, a skunk 2 alpha header, and a 3 inch Thermal R&D exhaust on my 2010 with a Vit Tuned Flashpro tune and that thing was pretty quick for a 197hp 2.0. The secondary O2 disable passed emissions in AZ too with an OBD scan as well.
 
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AdamD19DFK8

AdamD19DFK8

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Ripped the heat shield out today, when the car's running you still can hear a rattle coming from the front left of the engine bay right around the VTC actuator area. Better not run it again until I swap it out.
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