Quote:
Originally Posted by steve99
Even if the sensor was inaccurate the ecu would not know so why doesn't it try to get AFR to 12.5 ?
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It seems that the stock sensor loses accuracy richer than 12.5-13. As you're N/A you could create a map to run safely at 12.6/12.7 to dial in the MAF before running desirable ratios, just dial back some advance while doing so.
You seem to be missing how open loop fuelling works mate. It doesn't look to see how the end result compares to the O2 sensor, as far as the ECU is concerned it doesn't exist in open loop. It does a calculation based on the air intake in g/s and calculates the fuel needed to hit the AFR in the fuel table. The LTFT is set by consistent STFTs occurring and those only happens in CL operation.
Here's an OL example:
At 5000rpm the MAF is outputting 3.6v, the MAF scale shows this as 90g/s. The ECU then looks at the target AFR and calculates that x amount of fuel is required to hit the target AFR basedon 90g/s of air and then adds the LTFT on top.
If you now change 3.6v to 100g/s the ECU will now assume more air is entering the engine and to continue to make the target AFR more fuel is required, so the resultant AFR will become richer. If the ECU still has a similar LTFT due to the CL operation it will still add this on top, potentially making it even richer.
This is why ensuring that areas of CL to OL operation are scasled well on the MAF. The car I've done recently has 0 LTFT everywhere and I haven't disabled them or moved the WOT area out of the area of correction learning, although I probably will in the long term.