[categimperat]

hello all, this is my first time posting here and my first accord, although not my first honda.
I recently picked up a 2008 accord ex-l v6 coupe with a 6 speed. it had been sitting without moving for around half a year before i bought it (i towed it home although it did start right up so i could get it into a parking space).
i've given it a tune up and replaced a lot of things, including: timing belt/water pump/idler pulleys; serp belt; spark plugs; new battery; ect sensor; brakes/rotors.

it starts without complaint, but it runs rough due to misfires on cylinders 1 2. i moved ignition coils 1 and 2 to cylinders 4 and 5 which didn't move the misfires, but another misfire on cylinder 6 appeared. EDIT: after a short drive a misfire on cyl 3 manifested as well.
the spark plugs are brand new NGKs, i didn't bother trying to move those. there is also an ECT sensor code; i replaced the ECT with an OEM unit and it persists. there are also ABS codes 61 and 83. there were various TPMS codes (no transmission from all 4 wheel tpms sensors and a FCAN failure), which didn't return after clearing.

any idea what the root issue of this could be? might it be a failing ECU? thanks.

 

[WiiMaster]

Is your timing set correctly?

 

[categimperat]

Is your timing set correctly?

yes, i made sure of that when doing the timing belt.

 

[categimperat]

i checked the battery voltage (12.6) and the alternator voltage (14.05). i think these are in spec.

 

[Miker]

@categimperat
I'm gonna give a WAG that you purchased the NGK plugs from Amazon or eBay.

 

[categimperat]

@categimperat
I'm gonna give a WAG that you purchased the NGK plugs from Amazon or eBay.

What’s a wag? And yes they were purchased on Amazon.

 

[Miker]

WAG= Wild A$$ Guess and Amazon along with eBay has been selling NGK's that have been found to be fake.

And the exact symptom you are describing is indicative of fake plugs as of late.

 

[categimperat]

WAG= Wild A$$ Guess and Amazon along with eBay has been selling NGK's that have been found to be fake.

And the exact symptom you are describing is indicative of fake plugs as of late.

all right, I’ll go to autozone and get some plugs today then. Would the other problems (ect sensor abs stuff) have anything to do with the plugs as well? I’m not sure why the ect code in particular is persisting, I made sure to get a new oem honda unit.

 

[Miker]

Which ECT did you replace? there may be two separate coolant temperature sensors. I believe.

Did the misfires occur soon after the sparkplugs were replaced? or did misfires show up prior to the sparkplug change?

Your battery is new so it's probably not an electrical thing although the cables going to the battery may be corroded and causing the ECU voltage code.

 

[categimperat]

Which ECT did you replace? there may be two separate coolant temperature sensors. I believe.

Did the misfires occur soon after the sparkplugs were replaced? or did misfires show up prior to the sparkplug change?

Your battery is new so it's probably not an electrical thing although the cables going to the battery may be corroded and causing the ECU voltage code.

Thanks for your help.
I replaced the one on the front right side of the engine. I don’t think I saw anything about a secondary sensor.

I didn’t scan for misfires before changing the plugs. I think the car may have run a little rougher after replacing them but I can’t really say because I didn’t run the engine for more than 60 seconds before doing so, and I replaced a bunch of things like the belts before doing the plugs and starting it up again and scanning.

It’s certainly possible that the wiring harness was compromised, it sat in a grass lot for half a year so maybe a rodent chewed at it. I’ll take it to the dealer tomorrow for diagnosis, hopefully they can find something. Any other ideas?

 

[categimperat]

Which ECT did you replace? there may be two separate coolant temperature sensors. I believe.

Did the misfires occur soon after the sparkplugs were replaced? or did misfires show up prior to the sparkplug change?

Your battery is new so it's probably not an electrical thing although the cables going to the battery may be corroded and causing the ECU voltage code.

Okay, I replaced the spark plugs with densos and it didn’t fix anything. Since I last replied misfires on all cylinders have started showing.