How do you tune using a piggy-back controller (like GReddy E-Manage) while the stock ECU is in closed-loop and still adjusting the long term fuel maps?

We're struggling with this, trying to tune with a wideband O2 on street and dyno, but we can't reproduce the AFRs deterministically between runs because the ECU is still "learning" the fuel curves and adjusting them. Of course this is a non-issue for WOT tuning, but I also need to tune while not under load so that day-to-day driving works too.

What are people doing to circumvent this? And what happens if I complete a tuning session only to have the ECU continue its learning cycle and re-adjust the long term maps?

Another thing to note too is that I've been having to reset my ECU for various things (mostly to clear OBD-II rear O2 sensor codes) which means my ECU never gets to complete its learning cycle.

This is for a 2002 Honda Civic Ex (D17a2) with upgraded 370cc injectors. I'm running 8psi boost. We're using the e-Manage airflow map and the additional injection map for fuel tuning. The axis for the maps are as follows...

Airflow: Adjust MAP voltage according to TPS & RPM
Additional Injection: Add injector duty cycle according to MAP voltage & RPM

What else is odd is that we're NOT clamping the stock MAP sensor voltage and the stock ECU is NOT complaining -- Honda ECUs are notorious for throwing codes when MAP sensors see boost. Anyone know why I'm not seeing MAP codes? I am however seeing a P1106 code indicating out-of-range voltage from the barometric pressure sensor (which is located in the stock ECU casing). This may or may not be related to not clamping the MAP voltage. Has anyone else seen this or know how to resolve it?

If you're interested, here's some info on Honda ECUs' learning process: http://www.hondata.com/techclosed.html

Thanks in advance for any help!

--J.

 

Try to get the part throttle long term fuel trims within +/-5% of stoichiometric.

 

How do I do that when the short term adjustments make the AFRs non-reproducible, and when I have to reset my ECU from time to time, thus resetting the longer term fuel trims.

And if I were able to do it, would it mean that if I ever disconnected my battery, my AFRs may be off again once the trims are re-learned?

Thanks!

 

If you set the corrections on the e-manage so that you're running close to stoich during closed-loop/part throttle conditions, then your long term fuel trimming should be minimal.

You need to worry more about the long term fuel trim, not the short term. Short term is not carried over.