Pulse Widths too High

[pgriffith]

I was A'taping my car today and my Pulse widths are as high as 25ms. They very but usally between 22-25ms. Is this too high? Also my car is running really rich. O2's read about 980mv. So If I lean it out and get the O2 readings where they should be will this lower my pulse widths?

[John_D.]

Yes your o2's are too high and your pulse widths are too high. The high o2's indicate that the pulse widths are too big, because the injectors are being told to stay open too long and driving up your o2's.

Get those down and the pulse widths will be a lot better.

Also, the pulse width can safely be higher at lower rpms, because there is more recovery time before the next cycle. So it depends on what rpms you are seeing the pulse width at.

24ms is 90% duty cycle at 4500rpms, and 100% at 5000.

At 6000, you should be at 18 ms (90%) or less.
At 6000 rpms, each 1 ms is 5% duty cycle.

Duty cycle % = rpms * pulse_width (in ms) / 1200

In an older post I may have said * .0012 but it's really divided by 1200... Slight difference... I don't remember if I had actually posted the formula before or not, but I just ran across it on some notes where I worked it out a while back.

[Arctc Wolf]

bigger injectors will help reduce pulse widths. also, if you're using the stock O2 sensors, it may read higher than it actually is. Wideband O2 sensors will help u see the air/fuel ratio accurately.

[pgriffith]

<blockquote>quote:</font><hr>Originally posted by Arctc Wolf:
bigger injectors will help reduce pulse widths. also, if you're using the stock O2 sensors, it may read higher than it actually is. Wideband O2 sensors will help u see the air/fuel ratio accurately.<hr></blockquote>

Where can I get these?

[pgriffith]

This is what I am seeing at WOT:

Engine Speed(RPM) Injector Pulse Width #1(mS)
2842 11.55
3298 18.27
3848 19.76
4273 19.93
4803 20.45
5306 20.04
5306 2.21
5576 23.43
4768 23.19
3760 21.56
4012 20.81
4287 21.63
4491 21.68
4683 22.08
4892 22.26
5081 21.28
5306 20.87
5461 20.57
5624 20.89
5772 25.95
5928 0
6009 34.63
3848 21.54
4100 21.07
4087 21.36
4245 20.98
4273 21.13
4387 20.89
4461 20.98
4569 21.07
4634 21.16
4717 20.77
4785 20.95
4874 21.38
3060 8.58
4700 23.22
4372 22.66
4416 22.91
4522 22.84
4585 22.31
4683 22.56
4751 22.18
4838 21.82
4910 22
5004 21.8
5062 21.31
5141 21.31
5202 21.33
5264 21.42
5328 20.86
5393 21.33
5461 20.81
5553 21.22
5576 20.87
5672 21.12
5722 21.51
5797 21.65
5849 24.56
2277 13.16
4929 21.89
4491 22.17
4650 22.06
4683 21.77
4785 21.62
4838 21.24
4910 20.99
5004 21.3
5062 21.09
5161 21.36
2186 5.61
2455 17.99
2575 18.33
2713 19.27
2867 19.32
3032 19.68
3233 19.47
2725 17.87
2788 18.85
2867 18.65
2944 18.88
3018 18.69
3104 18.97
3171 18.8

[ March 29, 2003: Message edited by: pgriffith ]</p>

[John_D.]

You need to get your o2's down first. Bigger injectors at this point will just make you run even richer. Once you get the o2's down, then see where your pulse widths fall. Bigger injectors are only needed if the pulse widths are still too long on your current ones.

[Dominic]

5672 21.12
5722 21.51
5797 21.65
5849 24.56

Thats not good at all... Did you get the miniAFC yet??

[DEE97GTP]

Log your MAF frequency, Ltrim, O2. Find out what your fuel pressure is. If your Ltrim is really negative(-15 or higher) then you MAF is reporting alot more air than it should.

DEE

[malloynx#2]

i'm seeing 24ms at 6000 rpms.. i need some lt1 injectors

[Magnus]

yea, lets find out WHY they are so high.

Log things like MAF frequency and LT's.

Did you mess with your MAF setup at all?

When I ditched the MAF post in my 97 TB and just let that maf hang in there, my PW's were really high until the PCM lerned.. but when I put in the 99+ sensor my calibrations were more on scale.