Originally Posted by
macakin I've seen the same problem on most of the cars with a chipped ECU's
It's all in the tune. If you have a chipped ECU but stock injectors/maf then you should be fine.
Technical reason as to why:
Our ecu's are tuned for 259cc injectors. They have cranking enrichment and cold start tables. They basically dump more fuel when your cranking it, or when you cold start it. This enrichment is part of the calculation to get a the total amount of fuel that injectors should spray.
When you install bigger injectors (333cc on VE's), you will have more fuel being dumped per pulse width. This is why you need to adjust your K value to, otherwise you will be too rich. By adjusting your K value you are adjusting another variable that is part of the calculation to get the total amount of fuel to spray. Adjusting the K value is a good way to adjust your AFR's across the whole fuel map, but doesn't mean your cranking and cold start enrichment will be right anymore.
Thus you need to adjust those tables for the car to run like it did before. Now if you adjust your K value to be too lean, then you will actually have to add to the enrichment tables otherwise you will have lean spots while cranking/cold driving.
Same goes with the MAF, you mess with the K value when you install a new MAF thus you mess with all of the calculations.