DSM injector constants

natesully · Post by **natesully** » Sat Dec 03, 2005 8:10 pm

I have some 440cc DSM blue-tops in my Miata. They have 1.7 ohms per injector, so I set MS up for low inpedence. Or so I thought- I had PWM at 75%, and the PWM threshold at 25.5 ms

. The car ran insanely well, other than my spark issues. Now, I tried to set the PWM threshold to 1.0ms, and PWM% to 50%. The car can be made to idle, but when I floor it my fuel goes by-by. Completely. No amount of VE can bring it back.

So I set open time and PWM threshold to 1.5ms, and PWM% to 75%, and the car runs great. I have 15% VE at idle (huh? open time effects it that much?) and my reqfuel is 6.8, as per the calculator. Am I missing something? Shouldn't I be running, like, 30% PWM and really low open times? I have a V3 board, with flyback built.

Does anyone here have DSM injectors w/o resistors, and mind sharing their constants?

AnDrEw · Post by **AnDrEw** » Wed Dec 07, 2005 10:38 am

I'm running DSM bluetops, I thought they were 450cc though. However, I'm running near the recommended PWM% and threshold for low impedance injectors. My cars in storage so I can't see my constants, but PWM% IIRC was around 25 and threshold was 0.9. You might be having problems with your flyback circuit.

The problem I had with these injectors is they make loud clicking noises compared to my stock injectors and another injectors I've messed with. I don't know if thats normal or not for DSM injectors.

Andrew.

natesully · Post by **natesully** » Wed Dec 07, 2005 5:58 pm

Well, mine click, my friend's click (he has a 300ZX) and actual DSMs I've seen click.

Yeah, I'm gonna pull MS and check everything out soon. I think you are right.