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B18C/Link G4+ AFR Issues

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Hey Everyone,

I have just started to configure and tune my engine (B18C) on my Link G4+ and I'm having some bizzare issues with fueling when opening the throttle. It's forcing me to make some very coarse adjustments to meet a good AFR with such little increments of RPM.

I have datalogged a quick drive and it is somewhat driveable but the AFR seems far too erratic, it also seems like i'm having to remove more and more fuel as the RPM and load increase...? Could someone have a look at the tune and datalog to see if they can see anything not quite right? Could I have set a master pulse width too high and ruined the resolution of my fuel table?

Wideband is a Zeitronix ZT-3, injectors are Deutschwerks 1000cc.


Attached Files

Hard to really see what you are talking about with that log. You only get to a max of about 10% throttle and 3000Rpm and have only passed through about 10 fuel table cells in the whole log.

However, a few changes I would suggest before going too much further with the tune - Unlikely related to your perceived problem, but they will potentially make your life more difficult:

Enable the open loop lambda table.

Zero out the 80°C cell in the warm-up enrichment table since you are still partially operating in that cell when warmed up currently.

Turn off knock control or set retard limit to 0 so it is not randomly pulling timing out.

Accel enrichment looks over-active in some areas of your log, possibly some of your erratic fuel is coming from this - may need more deadband or less sensitivity.

You need an IAT sensor connected and working.

Your VTEC is set to engage at 3500RPM, that is unlikely correct.

Update firmware, yours is quite old.

You have a lambda target of 0.95 at WOT, I would start with that at more like 0.87

Ignition dwell time is set to a flat 4.0ms, this is pretty extreme for most common COP coils. Probably wants to be more like half that value at 14V.

Thanks for those points Adam, I'm really appreciative that you've taken the time to do that for me.

I could not see a tabled option for open loop lambda - found the option for the Closed Loop Lambda Table though, which i've set to 'Auto'.

There was a couple of points in the datalog where I would slowly roll the throttle in and immediately run into a very rich condition which is what has caused the car to have those 2 flat spots. (shown with RPM) But it's a little weird the TPS trace did not resemble this action.

The IAT was reading abormally high at 45-55C before the drive (the intake did not feel anywhere near that) so for the purposes of any trim interference I just turned it off. Will see how the car responds with these changes.

Again, thank you very much for helping me with this - we're lucky to have someone like you on this forum.

Just to add some resolution to my issue;

I have since found the fuel pressure gauge to be reading incorrectly. I have wired in a fuel pressure sensor and instantly found the fuel pressure was far from the target, it has been adjusted and is now working perfectly.

I surprisingly found the old injectors for the car, rewired new OEM plugs and installed them and it is obviously more stable to make adjustments for the AFR than the Deautschwerks 1000cc injectors.

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