How far off should a MAF transfer function be, before you suspect the injector data is not correct?

robert presti

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I'm working on tuning my car. I cheeped out on injectors, and now more than ever might be regretting it. Bought 80# injectors off EBay with no data sheet, so I'm using the Ford Racing data in the tune. The ones I bought look like Siemens knockoffs, which look I the style Ford racing uses, but not sure. I'm going to try to run the car this week with the SCT transfer and clock the MAF different ways to see if it changes to close to right. This car is also return fuel now, so fuel pressure is different at different areas. One reason I think the injector data might be wrong is how much fuel I've had to pull for start up return less or return.
 

robert presti

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I have a 2000 mustang GT built 4.6 with a Procharger. I don't remember what BP modifier is, all I'm doing at the moment is using data transfers from Advantage 3. Blown 2 valve with BA5000 in a 3" tube and it is blow through. So far it looked liked the car is closer to right with the data with a 3.5 in tube. I'd have to check the displacement again in the tune, it was at one time altered less than 10%, but not sure it is now. When I did that it was because of high load numbers at idle.
 

robert presti

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I checked the tune and displacement is not altered anymore. The issue with load must have been worked out with the addition of the blow off valve and MAF screen ( flow straighter). to run like a stock car I probably need another blow off valve to keep MAF add count fluctuation down at low throttle. Still seeing 50 add count fluctuations with the 30mm bypass before the intercooler and 50mm bypass after. Before the 50mm bypass I was seeing 100 add count fluctuations, now about 50 where 0 is ideal. I don't know I'll do it, but it would be interesting to see which did more to lower the MAF fluctuations more at this stage. The simple screen to straighten MAF airflow or the added air release of the supercharger. This is a built engine with long tube headers and still hitting 17+ psi of boost, so it is always moving a ton of air even at low throttle.
 

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