Fuel injector impedence question

[Fierofool]

How much does impedence affect fuel injectors?  What would be the effect of going from 14.3 ohms to 15.9 ohms do with all other perameters being the same? 

[GTRS Fiero]

Heat?  There would be a marginal increase in temperature.

[Fierofool]

Does it change the pulse width or flow rate? 

[GTRS Fiero]

It does not seem so, but it opens more quickly.  Maybe slightly.

There are low-impedence injectors (2-3 Ohms).

[GTRS Fiero]

Thinking about this, fuel pressure is still the same, the injector nozzle is still the same, and the open/close points are the same, so the flow rate should not change.  There may be a marginal change in pulse width, but the computer may well compensate.

[Raydar]

How much does impedence affect fuel injectors?  What would be the effect of going from 14.3 ohms to 15.9 ohms do with all other perameters being the same?

By my way of thinking, none. None at all. They are both considered "high impedance" injectors.

As GTRS alluded to, 2-3 ohm are considered "low impedance" injectors. Which (as near as I've been able to observe) just so happens to coincide with ridiculously high flow rates. 40-50 lbs/hr., etc.

As long as they're in the teens, I wouldn't worry about it. At all.

Edit - To further muddy the waters, there is a difference between "impedance" and "DC resistance". (This is particularly important when discussing hi-fi speakers. Perhaps not so critical, when discussing injectors.) But some engineer, somewhere, might take issue, so... there's my caveat. :p

[GTRS Fiero]

That begs the question: Are you trying to change the pulse width or flow rate by increasing impedance, or are you troubleshooting a rich condition?

Would you believe there are 70-Ohm injectors?

[Fierofool]

In the past I've seen precautions given on PFF that one should be sure the replacement injectors are of the same impedance as the old ones. 

Just by changing out injectors, I now have a bad stumble at normal acceleration.  Also, at idle, the engine will drop to 5-600 rpm and then kick back up to about 2000, slowly getting back to 1100 for a while before near-stalling again.  Sometimes it will stall. 

Sandman07 had the same problem and he had to reset the TPS.  Though we changed nor touched anything else, this issue surfaced immediately after startup.  These injectors flow a little more than the old ones and seem to work well out on the highway.

GTRS, I changed to the upgraded injectors for the 3.4.  The old injectors were 14.3.  The new ones are 15.9. 

[Raydar]

70 ohm? What is the application?

[Raydar]

Charlie... have you got a link / part number to your injectors?

[GTRS Fiero]

In the past I've seen precautions given on PFF that one should be sure the replacement injectors are of the same impedance as the old ones. 

Just by changing out injectors, I now have a bad stumble at normal acceleration.  Also, at idle, the engine will drop to 5-600 rpm and then kick back up to about 2000, slowly getting back to 1100 for a while before near-stalling again.  Sometimes it will stall. 

Sandman07 had the same problem and he had to reset the TPS.  Though we changed nor touched anything else, this issue surfaced immediately after startup.  These injectors flow a little more than the old ones and seem to work well out on the highway.

GTRS, I changed to the upgraded injectors for the 3.4.  The old injectors were 14.3.  The new ones are 15.9.

That sounds like a vacuum leak.

[GTRS Fiero]

70 ohm? What is the application?

Dunno.  I saw that when looking for something else.  Seems like a waste.

[Raydar]

That sounds like a vacuum leak.

I'm thinking it also sounds like what happens when you plug disk type injectors into a Fiero ECM.
But I'll withhold comment until I see what the injectors are.

[Fierofool]

Bosch 280 150 941 @ 14.3 ohms, old injectors flowing 14.1 or 14.4 # /hr, depending upon which Bosch chart you consult.  43.5 psi
Bosch 280 150 415 @ 15.9 ohms, new injectors flowing 16.6 #/hr @ 43.5 psi.  These are Bosch EV1 injectors.  4 pintle.

[Raydar]

Heh... I found your post on the injectorplanet website. And indeed, they should work. All I can think of is that they might be a bit rich at idle.
Did Sandman's TPS reset fix the problem? if not, it might still be a bit "fat" at idle.
Does it get any better (or worse?) after it's good and warmed up? I ran 19s in my 3.4, and it idled okay with a stock tune. (Made my eyes water, though, until it warmed up and went into closed loop. Never did any of the hunting around stuff, though.)