Why Tuners Hate 60lb Siemens Deka's

[bradles024]

I take it that's not a good idea then. So what would be the right way to use these injectors? I had used the stock battery offset and had a low slope of about 130, and that didnt idle very well. This way seems to idle better, but with AFRs of around 12 its too rich.

[IH8TOADS]

This is what's happening in your case. You're getting 1.391ms from the min_pw and 0.5ms from the deadtime ADDER. The minimum pulsewidth is effectively 1.891ms. These cars idle at 1.6ms so the PCM can't even pull fuel to reach stoich....hence why I asked what your LTFT is.

The minimum pulsewidth in the software is used to ensure the vehicle gets a delivered amount of fuel, however it's actually a statistical figure in which below the stated min_pw actual fuel mass delivery will deviate >5% from the calculated fuel mass delivery. Therefore it's not recommended to run an injector below its min_pw, but in the case of an XR6T at factory idle, you have to if you want to run it at stoich AFR.

The deadtime figure you run at operating voltage will determine what min_pw you can use to achieve stoich.

For everyone wondering why the Injector Dynamics range is so good....have a look at how low the min_pw figure is. Essentially at very very low commanded pulsewidths.....your engine gets that commanded fuel mass within the 5% tolerance limit :-)

[bradles024]

LTFT B1&2 are both at 0.0 at idle. STFT 1 is at 6, STFT 2 is at 42. So how do you get these to idle at stoich? AFRs were at 14.6 when the different scaling was used, but the idle wasnt as smooth.

[IH8TOADS]

Scaling alone won't make the idle perfect at stoich. I get asked this stuff all the time.....I suggest you go to your software provider and get them to teach you how it all works.