1979 930 Fuel Injector Opening Pressure

[madkow]

So I've taken it upon myself to test pop test all my injectors. I noticed that 4 of my injectors opened up at 40 psi, but 2 injectors opened at 38 psi and 39 psi. Is this bad? Shouldn't they all open up at the same psi or is it that the spray pattern really matters more? I'm just curious. These injectors come from a CIS system on a 79 930.

[David]

Since they spray continuously, I can't imagine that the opening pressure would matter much.

[Craig 930 RS]

Your pressure differences are fine.

It (can) matter(s) quite a bit. According to the local guy who does injectors/tested mine, the opening pressure ("crack pressure")




coincides with injector leakage. One of mine opened way too early (about 8 psi too early and 'flowed' a ton more than the rest......and consequently dribbled profusely when the crack pressure threshold was reached on the way down.

[RarlyL8]

38 to 40 pounds cracking pressure is not significanly different. You should be fine as long as they are not leaking when closed.

[Craig 930 RS]

Isn't that what I just said?

[NathanUK]

it's always nice to get a second opinion even if it is worded a different way.