Brent V

OK, I just logged block 002 on my 2000 A4 1.8T and it's showing my mean injector time as being about 22ms at about 5500 RPM's. The thing that messes me up is that the maximum injector on time allowable at 5500 RPM's is 10.9ms so that doesn't make any sense.

If I do the duty cycle calculation using the 22ms value I come up with 99.7% duty cycle so that means my injectors can't push any more fuel, no?

duty cycle calc I'm using is rpm x injector pulse width/on time and then divide by 1200 to get duty cycle.

Can someone clarify all of this for me and tell me if I need new injectors or not? (running lean right now)

-Brent

dingster

You forgot you have a 4 cycle engine. The injectors can stay on for 2 revolutions of the crank. So at 5500rpm, your 100% duty cycle would be:

60sec/5500rpm * 2 * (1000ms/1sec) = 21.8ms.

The maximum ELECTONIC pulse width allowed by the dbw Motronics software is 23ms. So even at lower rpms, the pulse width is electronically limited to 23ms. Above about 5000rpm your pulse width is limited by rpm.

Attached is a little spreadsheet I made that calculates the dutycycle on a dbw car.<ul><li><a href="http://web.njit.edu/~dxd0835/Images/LOG-01-110-xxx-xxx.xls">http://web.njit.edu/~dxd0835/Images/LOG-01-110-xxx-xxx.xls</a</li></ul>

Brent V

Group A: '002
RPM Load Inj. On Time Mass Flow
TIME
STAMP /min % ms g/s
0.5 3360 49.6 7.38 34.17
1.5 3440 80.5 12.71 62.31
2.05 3560 135.3 20.09 92.03
2.64 3640 138.3 20.09 98.61
3.25 3760 136.1 20.09 98.06
3.99 3880 136.1 20.5 100.97
5.01 4080 135.3 22.55 106.5
6 4240 133.8 22.96 108.72
6.89 4440 132.3 22.96 111.08
7.55 4560 131.6 22.96 113.53
8.15 4680 130.8 22.96 116.03
8.83 4760 130.8 23.37 119.53
9.8 4880 129.3 23.78 119.14
10.81 5040 126.3 23.37 121.72
11.74 5200 124.8 22.96 125.47
12.35 5320 124.1 22.96 126.03
12.95 5360 121.8 22.96 123.78
13.55 5440 121.8 22.96 127.89
14.5 5560 120.3 22.55 127.92
15.5 5640 118.8 22.14 128.39
16.5 5760 116.5 21.73 126.83
17.15 5800 115.8 21.73 127.25
17.75 5840 115.8 21.73 129.75

Brent V

that answeres my question as well!

dingster

Are you running some kind of custom chip? What does your O2 voltage read? Log block 43 to see if you have enough fuel.

Mike O.

...anything above 14.5ms is considered static (full rated flow). I know that there is some tunability above 14.5 (you can affect the mix in a linear fashion) until above 16ms. The concensus seems to be 16.32ms.

Mike O.

dingster

16ms is the limit for nondbw. dbw is 23ms.

Brent V

Group A: '031 Group B: '003
Voltage Voltage Bin. Bits Bin. Bits RPM Mass Flow Load Ign. Timing
TIME TIME
STAMP V V STAMP /min g/s % °
0.22 0.13 0.495 0 3040 14.94 11.4 37.5
2.01 0.745 0.625 1.71 3120 77.81 36.5 9
2.96 0.775 0.68 2.45 3240 85.56 33.7 3.8
3.97 0.785 0.715 3.47 3440 90 37.3 3
4.97 0.77 0.71 4.47 3640 96.33 37.6 4.5
5.62 0.825 0.77 5.33 3840 98.28 38.4 3.8
6.22 0.825 0.785 5.92 3960 101.86 38.8 3.8
6.82 0.835 0.79 6.52 4080 104.22 39.6 6
7.55 0.835 0.795 7.13 4200 109.67 40.4 3.8
8.57 0.835 0.8 8.07 4360 109.67 41.6 5.3
9.57 0.84 0.8 9.07 4520 114.39 42 6
10.42 0.85 0.81 10.06 4680 116.19 42.4 3.8
11.02 0.85 0.815 10.72 4800 121.06 42.7 3.8
11.62 0.855 0.82 11.32 4880 120 43.1 3.8
12.22 0.86 0.825 11.92 5000 122.31 43.5 3.8
13.17 0.855 0.825 12.65 5040 122.47 43.9 6
14.17 0.855 0.815 13.66 5200 122.08 44.3 6.8
15.16 0.855 0.815 14.67 5320 123.33 45.1 7.5
15.71 0.855 0.815 15.44 5400 123.53 45.9 5.3
16.31 0.855 0.815 16.01 5480 125.67 45.9 7.5
16.91 0.85 0.815 16.61 5560 122.67 46.3 8.3
17.64 0.845 0.805 17.21 5640 126.97 47.1 8.3
18.57 0.86 0.86 18.07 5680 127.03 47.5 9
19.57 0.81 0.79 19.07 5640 9.08 8.6 13.5
20.44 0.025 0.015 20.06 5480 16.19 11.4 12
21 0.02 0.01 20.71 5200 15.11 11 10.5

Brent V

Chip is GIAC J31 with boost controller set to 1.2bar max

dingster

Looks like you're ok.. .85V is around where you want to be.