Running Rich, Misfire, idle surge

K-Series Programmable ECU installation questions / support issues
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EX-THIC
Posts: 7
Joined: Thu Oct 05, 2017 4:46 pm

Running Rich, Misfire, idle surge

Post by EX-THIC »

Hey guys, I need help with a AFR issue prior to having this issue my car ran fine. My AFR would be at 11.50ish on idke and the idle would surge from 800-1000 RPM.
Cant really test drive It because it would misfire like crazy. Im able to adjust fuel on pro to make the afr be
14. 7ish but it would still have an idle surge/run rough and im just band aiding the actual issue. I know it's not tune related because it ran fine prior. Im not sure why it's just dumping fuel. Ive even lowered fuel pressure but no changes to the AFR.
Things I replaced/things i checked:
All four coil packs
Brand new 410cc RDX injectors
Spark plugs
ECT
Both camshaft sensor
Crank position sensor
Fuel pressure regulator
Fuel filter
MAP sensor replaced twice
TPS
IACV is blocked off
Valve lash has been performed 4 times
Got another engine harness
Replaced TB gasket
Compressor check 180psi all across cylinders
Cylinder leak down 100psi minor psi lost
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Spunkster
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Posts: 23872
Joined: Fri Sep 20, 2002 5:06 pm
Location: Hondata

Re: Running Rich, Misfire, idle surge

Post by Spunkster »

Have you narrowed down the misfire to one specific cylinder and is there any combustion on that cylinder?
Handies in the Honda
Posts: 2
Joined: Thu Feb 08, 2024 9:57 pm

Re: Running Rich, Misfire, idle surge

Post by Handies in the Honda »

Posting a datalog will help out. Spray around the manifold to check for air leaks. Check for exhaust leaks too. Have you tried replacing the O2 sensor or iat sensor yet?
EX-THIC
Posts: 7
Joined: Thu Oct 05, 2017 4:46 pm

Re: Running Rich, Misfire, idle surge

Post by EX-THIC »

Spunkster wrote: Mon Jun 09, 2025 9:13 am Have you narrowed down the misfire to one specific cylinder and is there any combustion on that cylinder?
Hard to say because once it’s warmed up sometimes the misfire is there and sometimes it’s not. I know when I slowly throttle it I can feel the car misfiring but once’s gas it quick the misfire doesn’t happen. The car runs so rich badly it fouls the plugs badly so I keep on having to clean them.
EX-THIC
Posts: 7
Joined: Thu Oct 05, 2017 4:46 pm

Re: Running Rich, Misfire, idle surge

Post by EX-THIC »

Handies in the Honda wrote: Mon Jun 09, 2025 9:55 am Posting a datalog will help out. Spray around the manifold to check for air leaks. Check for exhaust leaks too. Have you tried replacing the O2 sensor or iat sensor yet?
I’ll post a datalog of it idling but that’s the best I can do cause driving it misfire so badly. Sorry I forgot to mention I replaced the 02 sensor and I had it set on open look the car still ran the same. Yes, IAT sensor has been replaced too
Handies in the Honda
Posts: 2
Joined: Thu Feb 08, 2024 9:57 pm

Re: Running Rich, Misfire, idle surge

Post by Handies in the Honda »

Are you running cat? Could possibly be clogged.
EX-THIC
Posts: 7
Joined: Thu Oct 05, 2017 4:46 pm

Re: Running Rich, Misfire, idle surge

Post by EX-THIC »

Handies in the Honda wrote: Mon Jun 09, 2025 12:10 pm Are you running cat? Could possibly be clogged.
I’m not running any cats it’s just a 3 inch exhaust with a muffler.
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