Fuelling Issues (ECUtek ROM)
 

I thought I'd share some symptoms and asks for ideas and advice from some of the more experienced. 2 issues not related but occurring at similar RPM.


1st of all the PI seems to cut off for a brief period. It has no impact on the resultant AFR so it's not an issue but it's a tad strange. The PI/DI ratio table is as below:
https://dl.dropboxusercontent.com/u/...PI%20Ratio.jpg


But this is the injector open times:
https://dl.dropboxusercontent.com/u/...0Injectors.jpg


Any ideas?


The other issue is that the car goes lean momentarily between 4.2-4.6k:
https://dl.dropboxusercontent.com/u/...ssue%20AFR.jpg


You can see the commanded AFR. The point it goes lean is bang in the middle of 2 MAF scalar points, the voltage points sit almost exactly at 4.2 and 4.6k RPM, so it's not a MAF issue. My initial thought is that as both intake and exhaust cams ramp up then the overlap increases as below:
https://dl.dropboxusercontent.com/u/...Issue%20OL.jpg


My questions:
- Is the AFR actually true? You can see from the top images that the fuelling hasn't changed through that range. Is there a chance that the overlap is causing fresh air charge going through the cylinder causing leaner readings?
- Could the PI/DI ratio have an impact? I've moved the ratio back to stock from the tables above. The PI is showing as 50% in that range, but OEM is 100% DI. Could that help?
- Would just enriching out the fuelling table at 4400 be the right way to improve this?


Any other ideas?

The PI shut down but the fuelling is added via the direct injectors.

The switching between injectors is as the car was tuned from the factory.

But at these loads I would expect it to be 100% DI between 2400 and 4800 as per the top map, not between 4500 and 5000. It doesn't really tie in with either map or be an interpolation between either.

For reference the cold map is stock, the warm and hot maps are both as the lower map shown.

What's the load being logged when this happens?