Injector weirdness

[Rittmeister]

Background - my S13 has a redtop SR20DET, stock everything except Walbro fuel pump.

This morning I went to do some running around, and just as I turned onto my street coming home I felt the power drop, felt the chugging we've all come to associate with running on 3 cylinders. Pulled into the garage, still chugging, still reluctant to rev. Left the car idling and did the injector test - unplugged one at a time. Sure enough, the cylinder closest to the radiator (never can remember if that's #1 or #4) showed no change when unplugged, whereas the other three caused a drop in the idle, just as you'd expect.

I shut the car down, took the groceries inside and put them away, went back to the garage and pulled out my trusty multimeter. The three functional injectors all read between 10 and 14 ohms between the terminals, just as the FSM says they should. The last one, that I figured was dead, read 220 ohms, just a little out of spec.

So, being a dummy, I fired the car up again, and here's the strange part - the injector went back to working, and the car idled fine. Shut the car down, checked with the meter again, resistance was down to 18 ohms. Still out of spec but a lot closer. Went for a ten minute drive, where nothing at all was wrong or strange, checked upon return and now the resistance is within spec - 13.8 ohms.

I should probably replace the injector, but can anyone explain this? I've had injectors die on other cars (SE-R, a friend's KA S13) but never die and be resurrected, so to speak. These are the stock 370cc purple injectors, FWIW.

Any thoughts appreciated.

[SoSideways]

Could be the solenoid inside the injector is on its way out.

Or it could be the solenoid got stuck for a bit and threw that resistance, then when you fired it up again, it knocked it loose and thus returned to spec.

[spirit]

I'd prob run a bottle of injector cleaner on the next fill up. And not worry about it unless it happens again.

** I wouldn't worry about it because I myself had a coil pack go out on me once, didn't have a problem driving home the 40miles on the freeway on 3 cylinders. Just get to 60mph REAL slow heh.

[DeatschWerks]

The injector will have to be replaced. The coil is on its way out. There is nothing you can do about a bad coil.

Most of the time when a coil fails the injector completely stops working, staying closed. But there are rare cases where the injector does what you are describing, going back and forth but it will eventually stop working. That is a much worse case than the injector completely stopping because you could get a lean condition as the injector goes in and out from firing and not firing.

There could be the outside chance, very outside, that the connectors are just not getting good contact. You could try cleaning up the prongs.

Don not bother trying to run any cleaner through the fuel system. Cleaning the injector has nothing to do with the coil.

[Rittmeister]

The injector will have to be replaced. The coil is on its way out. There is nothing you can do about a bad coil.

Most of the time when a coil fails the injector completely stops working, staying closed. But there are rare cases where the injector does what you are describing, going back and forth but it will eventually stop working. That is a much worse case than the injector completely stopping because you could get a lean condition as the injector goes in and out from firing and not firing.

There could be the outside chance, very outside, that the connectors are just not getting good contact. You could try cleaning up the prongs.

Don not bother trying to run any cleaner through the fuel system. Cleaning the injector has nothing to do with the coil.

I figured it's on its way out and I intend to replace it, though I do appreciate the technical explanation.

As far as injector cleaner, back when I was messing with FWD SR engines, the conventional wisdom was never to use it because there had actually been a TSB from Nissan to the effect that injector cleaner was somehow bad for the stock injectors.

So, anyone want to sell me one or two stock 370s cheap? :D

[UNISA JECS]

I figured it's on its way out and I intend to replace it, though I do appreciate the technical explanation.

As far as injector cleaner, back when I was messing with FWD SR engines, the conventional wisdom was never to use it because there had actually been a TSB from Nissan to the effect that injector cleaner was somehow bad for the stock injectors.

So, anyone want to sell me one or two stock 370s cheap? :D

Thats true I remember this from my FWD days to on se-r.net and sr20deforum there was a TSB on this.