B18C Lean idle, stalling, rough running

s300 and SManager software questions & answers
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Spencer6895
Posts: 3
Joined: Sat Jul 30, 2022 7:18 pm

B18C Lean idle, stalling, rough running

Post by Spencer6895 »

Hello,

This will be my first post on this board, I have used it a couple times and it has been a great help looking as a third party. Today however, I need to create my own thread because I am truly stuck on this problem.

Little info about the car.
1993 Canadian Si civic hatchback
Fully built B18C. 85mm Arias 11:1 pistons, Manley turbo tuff rods, Factory ITR oil cooler, JE pro-seal head gasket, ATI super damper, GSR head stock ports, Skunk 2 Flat face valves, Supertech valvesprings and retainers, 68MM Throttle body, 4 Bar Map sensor, COP retrofit with D series coils, BRK8ES plugs, GT3076R Garret Turbo, Old ID 1000 injectors, 2 block vents and 3 valve cover vernts, Rywire Mil spec engine harness, Upgraded fuel pump (cant remember size but adequate), Battery is located in the trunk with very thick gauge wire going to fuse box.

S300V3 (not sure which ECU number as it was completely refurbished and sticker was removed (new caps, tested just a few months ago)

The engine was built several years ago. It has run flawlessly for about 6 years now only being occasionally driven and never tracked. Has been a blast to own. Car was professionally tuned by a very reputable tuner in my local area.

I Began having an issue of the engine idling very lean. The car stumbles and i am afraid to drive it for risking damage. The car also does not seem to be responding to fuel map changes. increasing fuel map by 50/100/200% does not change the AFR or how the engine runs but eventually i will not run if I increase the fuel map excessively (too much fuel). Also, If i rev the engine in this state it will stumble and die. If i am able to warm the engine up the RPM will stumble and die.

I have checked that there are no vacuum leaks (used propane around engine with all vacuum sources disconnected. There is no unusual knocking sounds, oil scans of engine are good. Compression is 200 across the board (cold). Valves are all adjusted correctly. Base timing is set at 16 BTDC. Crank to cam and cam-cam engine timing is good. New oil. New fuel. Fuel pressure reads 43 (or close cant remember exactly). Injector dynamic 1000 injectors flow tested to near perfect spec. No oil/fuel/coolant mixing. engine does not burn much oil at all. I have tried swapping in a known good ECU, no change. I have even swapped this engine from a EJ coupe to an EH hatch (unrelated but still factors out chassis harness). It appears as though all sensors are reading correctly. Car will stall if any injector is disconnected individually. Engine does respond to IACV changes. I have cleaned the throttle body and IACV.

I have had the tuner look over the tune and he cant find any issues. I am also a professional diesel mechanic for about 10 years now and do the majority of diagnosing for our shop so I pride myself on being able to troubleshoot accurately. I come to you guys humbly, looking for some help.

Thanks in advance.

Spencer
Attachments
Spencer_B18C-final-tune.skl
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Lean idle.s3d
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Spunkster
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Posts: 22737
Joined: Fri Sep 20, 2002 5:06 pm
Location: Hondata

Re: B18C Lean idle, stalling, rough running

Post by Spunkster »

Have you tried this ECU/s300 on a known running vehicle using the correct calibration for that vehicle?
Spencer6895
Posts: 3
Joined: Sat Jul 30, 2022 7:18 pm

Re: B18C Lean idle, stalling, rough running

Post by Spencer6895 »

Yes, the current ECU was bought second hand and came from a b18C that was parted out. My original ECU ran this tune for quite a while without issue.
User avatar
Spunkster
Site Admin
Posts: 22737
Joined: Fri Sep 20, 2002 5:06 pm
Location: Hondata

Re: B18C Lean idle, stalling, rough running

Post by Spunkster »

You need to try this now to make sure the ECU is functioning as it should on a working vehicle running the correct calibration for that vehicle.
Spencer6895
Posts: 3
Joined: Sat Jul 30, 2022 7:18 pm

Re: B18C Lean idle, stalling, rough running

Post by Spencer6895 »

Okay...

Both ECUs gave me different results on a friends car with their tune. One ECU gave me 17+ afr at idle, second ECU gave me 15+. didnt expect 2 refurbished ECUs to fail.

I guess I will need to get these ECU's repaired.

Thanks for the help
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