jnshk

OK, good.

OK, so injectors are rated at 1.4ms at 14v and 1.5ms at 13v, but commonly see voltage varying from 14 to 13 volts.

Wait, I thought it expected the value at 14.0v?

I'm a little bit confused about this one. Based on the published latency values, I'd expect this to be 0.1ms from 14-13 volts at 43 psi (see above). But it doesn't quite match the newly updated battery offset chart posted by DeatschWerks. If I'm reading it correctly--which I may not be--the offset from ... No, I have no idea how that table is meant to be interpreted. Why are there negative values?

I read that in the manual. So thankfully I at least had/have that right!


BTW, thank you for holding my hand a bit on this. Sometimes I think I've got it about figured out and then I get new data that makes me second-guess everything all over again.

jnshk

OK, so to clarify on the value entered into MS:

The expected value is at 14.0v but if your injectors generally see 13.5v, it's OK to use the 13.5v value... as long as the voltage offset value is correct. Right?

Can anyone tell me how to decipher the "battery offset" chart provided by DeatschWerks? [LINK] Why are there negative numbers on the table?

EDIT: I think I figured it out. I think that it's using 12.6v as the baseline for offset and either adding or subtracting depending on the fuel pressure and voltage. Does that sound correct? Can anyone verify this deduction for me?

EDIT2: Ok, the math seems to work out based on the above interpretation, so my next question is:

Based on the provided specs (assuming 43psi fuel pressure), at 14.0v the latency is 1.42ms and at 13.0v the latency is 1.47.
The difference across that one-volt-range is 0.05ms.
So I would enter 1.42 as the injector opening time and 0.05 as the voltage offset?

Does this methodology sound about right? I will need to verify my fuel pressure still and then adjust my numbers if it's above 43psi, but does my method for determining the values sound right?

Braineack

iTrader: (62)

sounds right.

jnshk

Awesome, thanks for the confirmation!

jnshk

OK, so I finally got around to testing the fuel pressure. It matches spec for the '97 at idle (~36), as expected. About 41psi with the vacuum line removed, somewhere beyond 60psi under a few lbs of boost.

Do I use the value at idle or the value with the vacuum line from the FPR removed for my MS latency values?