Can a CIS fuel injector ever be truly "broken"?

[Hotwatermusic]

I have all 6 injectors out of my car right now ('83 SC) and am teetering between sending them off to get cleaned or just replacing them out-right. Is there anything that actually breaks or wears out inside the injectors under normal use? Is there anything that even a thorough, professional cleaning can't fix and would require complete replacement?

I don't want to send them off for cleaning if ultimately I'm gonna need to replace them, but don't want to spend $250 on new ones if a cleaning will get them back to new working order. Is there an at-home test one could do to see the functionality of the injectors? My embarrassingly crappy test for them was taking a can of carb cleaner with a straw on the nozzle, sticking the stray down the intake end of the injector, spraying the cleaner and watching the cone pattern come out the business end of the injoctor. All of them made a decent cone shape, but none made a 360 degree cone, more like 270 degrees or so. It was a nice fine mist though. Still, I have no idea is this is what I'm suppose to be looking for. Any advice?

[dtw]

There's not much point in sending them out - as noted in one of your other threads, they are not serviceable. Any local shop with an ultrasonic cleaner can attempt a cleaning for you.

They build up gunk and deposits internally - sometimes a cleaning breaks it loose, sometimes it doesn't. Corrosion is a factor due to fuel contamination and the years these cars sometimes spend sitting idle. So yes, aside from internal gunk/deposits, actual wear of the parts is also an issue.

A 270 cone is what most shadetree mechanics consider marginal, a pro shop would probably toss. That 90 degree area that isn't spraying often yields fuel droplets especially at lower pressures (think idle and cold start), which is hard to burn.

There is an even easier test if the engine is still in the car - pull all the injectors off the runners. Stick one bank in a safe container, still connected to the lines. Same with the other bank, in another container obviously. Remove airbox lid, turn on ignition. Lift the throttle plate arm manually while holding up one injector (still aimed into your container, though). Evaluate spray pattern at low pressure/idle, and through the range to full pressure.

Check each injector in this fashion, while the other five injectors spray into the vessels you stuck them into. I pull all six at once, so that the other 5 that aren't just dumping raw fuel into the cylinders. Monitor your containers as you test - especially at full pressure, they can fill up with fuel surprisingly fast.

Seems as though most injectors will yield a decent pattern at full pressure, but it is the part load and idle pressures that they fail. Particulary near idle pressure (throttle plate arm barely lifted), bad injectors will often dribble liquid fuel instead of atomizing it. This makes for a cantankerous, smelly, hard-starting car. At partial/cruise pressure, you will often note injectors that produce 'mostly' a cone of atomized fuel, but also spray some un-atomized liquid fuel.

In your case, since your engine is already out, I'd call around Euro/Porsche shops until you find one that has the MFI/CIS injector tester (and the ultrasonic bath, while you're at it). Your carb cleaner effort probably isn't giving you an accurate representation.

[robs]

If I remember correctly, there is a spring loaded metal needle that presses against a metal seat to close the injector. During operation, the needle vibrates and emits a fine fuel mist. The seat can wear out and worn injectors emit "rays" of fuel. BOSCH says the injectors can be still be used if the fuel leaves the injector as a spray, not necessarily in a perfect 360 degree cone. In my case, the injectors were worn out because ultrasonic cleaning did not help. I think it is more important that all injectors emit the same amount of fuel: Connect all injectors to the CIS system and collect the emitted fuel with small plastic bottles or containers. Remove the air filter box, set ignition on. Lift the air meter plate by hand and watch the injectors spray into the containers. Compare the amount of fuel from all injectors with a volumetric flask or an accurate digital scale (cheap). BOSCH says it is OK to replace individual injectors. If you are unsure, you can still buy 6 new injectors, not that expensive.

[RarlyL8]

Injectors do wear out. My rule of thumb is toss if 10 years old or they flunk the pressure test. You'd be amaized at how well a car runs with new injectors.

[Oracle]

Back when I had the SC I found out that a particular SAAB or Volvo (can't remember the details) used the exact same injectors, I bought them for a 1/3 of the price and used them. Since it was the same Bosch part worked perfectly and saved good money.