my 550's are maxed out at 18 psi

[94talonawd]

OK. Heres the story. I had recently put some allegedly PTE 550cc injectors and SAFC in my car. For some reason my injectors are maxed out past 100% at 18psi on my datalogger. I then turned my boost down to 12 psi, put all the corrections back to 0%, and then logged it on 3rd gear. I am getting around 2-3 counts of knock under 6k and about 10-15 counts of knock over 6k. My injectors are at around 88%-90%. Before when i had my 450's I can go to 15 psi with no counts of knock. Something is wrong here.

Now the question is...
Are the injector really 550's, or did I get ripped off? My broter had bought it a while ago for his 3S. He got it off of the 3/s forums.

[Shane@DBPerformance]

They might be the wrong injectors, but other things like clogged fuel filter, poor performing fuel pump, broken FPR, vacuum line to FPR missing, etc cause fuel injectors too max out also. What are your AFC setting like? What have you done about the MAF? A stock 1G MAF will experience overrun quite easily.

[94talonawd]

The fuel filter has just been replaced a few weeks ago. I have upgraded my fuel pump to a 3S. I have a 1g maf, I havent dont anything to it. I dont remember where my afc settings are at. I put them all to 0's for now. But my low settings were at -18%. My BTDC was at 0 degrees when I was running 18 psi on the safc. I tuned it for no knock. I didnt know that my BTDC was at 0 until i purchased a crank pulley from LSE. I put my BTDC back to 5 degrees and thats when I started knocking and put the boost back to 12 psi and put my afc settings back to 0.

[Shane@DBPerformance]

Your high throttle settings on the AFC should be -18% at the richest with the 550s. With it at 0%, it would fuel it just like 450s and the duty cycles should be quite high. You should at the very least, remove the lower honeycomb from the 1G MAF. It could still hit overrun, but at least that would be a start. If it starts overruning with the lower out, then you need to do some hacking, or switch to a different MAF. Having the BTDC at 0 would have helped your pump gas tuning and made it less likely to knock.

[94talonawd]

OK. Good, as long as I know that my injectors are really 550's I wont have much to worry about.
Also, by removing the lower honeycomb, i dont have to change the afc settings right? Because I know if you "hack" it, you will have to change the afc by 5%.

[niterydr]

Hacking the mas allows more air to pass through uncounted. It is a temp fix, and works, but the better solution is to upgrade to something that can count the incoming air. The factory 1g mas doesn't have the capibility versus the 2g mas. The 2g mas has a larger area to pass air through, thats why you have to compensate for the larger size. With having 550's, you would be better off upgrading to a 2g mas instead of hacking the 1g mas and having to take 15%+ percent out of the fuel curve.
IDC's are important, but you must remember if you don't correct the signal, the computer will use them like factory. When you take away signal (- on the s-afc) you are actually indirectly taking away fuel, thus lowering your injector duty cycles. If you are to far off the 'good curve' you can knock. This means you can knock when you are rich, or lean.
The hacked 1g mas is a proven way to go, don't get me wrong, but I personally like using the 2g mas. Accuracy sometimes costs more, but is better in the end.

[Shane@DBPerformance]

Running a 2G MAS with a stock 1G ECU isn't reading correctly or accurate either. Judging by how you can run 550s with out having to remove fuel on an AFC, shows you how far off it reads. If you want it to read correctly, you need to change the MAF compensation table, MAF Scalar, and MAF multiplier. Running a 2G MAS in a 1G without making changes to the ECU code is also a hack, it just happens that it doesn't require as much tuning to get it to work. You can make changes to the same tables and values in the ECU to make a hacked 1G MAF work like a stocker also.

You can't really knock from being too rich. It's just that when you are too rich, the motor starts misfiring slightly and gets picked up by the knock sensor.