CIS Injectors

[arbita1]

As my engine is out for rebuild I'm going through my CIS components to find any issues before reinstalling. I decided to send my injectors out to Special T Auto for cleaning and testing.

They called me the other day and asked if the car had been running. I told them other than some hot idle issues it had been. He was surprised. He said the spray patterns were awful and he was only able to get one injector to spray correctly. He's going to soak them for a week and try again. I may have to replace them with new ones.

I was under the impression that not much could go wrong with a CIS injector. These have over 200k miles on them.

[75 911s]

Not sure what it cost to clean, but $234 buys you a new set. I would recommend replacing the o rings and sleeves too. If you do just the injectors, you only need one o ring. If you replace the sleeve, there is another o ring on the sleeve to replace.

[arbita1]

Originally Posted by 75 911s

Not sure what it cost to clean, but $234 buys you a new set. I would recommend replacing the o rings and sleeves too. If you do just the injectors, you only need one o ring. If you replace the sleeve, there is another o ring on the sleeve to replace.

About $90 to clean and test. I already replaced sleeves and have new rings for the injectors.


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[Dale Durbin]

Was wondering the same thing about the CIS injectors as my car has been sitting idle for 12yrs. And I am soon tear into it.

[Bphawk1]

I had the same issue. I just replaced mine with new ones along with the o - ring rubber gasket and the sleeve rubber gasket. Seems to run much better . Not that expensive to new. My car is a 83 SC coupe with a 3.0

[72911]

Wow, 200K miles? I check mine myself with 6 old glass ice tea bottles with holes poked in the metal caps. Put each injector in the top and lift the air flow plate, let the fuel flow for about 10-15 seconds and you're done. This allows you to see the pattern but also just as important is to measure the fuel flow amount to make sure each cylinder is making the same amount of power. I do this about every couple of years (maybe 5k-8K miles). I change my fuel filter on the same schedule. A slightly bad spray pattern to me isn't always a reason to reject an injector but uneven fuel flow with a bad patten is definitely. There are acceptable values in the factory manual for flow and pattern but if it doesn't look right to me, that injector doesn't go back in. I have PILES of used injectors. Wow 200K miles....

[Charles Freeborn]

It's not a complicate part but it is a critical one with pretty tight specs. They do get a varnish like build up that can change their orifice specs. Cleaning is pretty simple - soak in acetone and gently back flow with compressed air. I had to replace one because it looked like this:


The rest were okay. As I recall replacement was about $40 each.

[arbita1]

That one is pretty bad. I had to replace one due to it being seized on the fuel line. When I got it off the threads were damaged. Also had to replace that fuel line. All the others looked to be in good shape from the outside. Guess not. We'll see what they can salvage and I'll replace the others that are bad.

[diy83sc]

Originally Posted by Charles Freeborn

ICleaning is pretty simple - soak in acetone and gently back flow with compressed air.

What you using to keep,the pintle valve open when you backflush?

[T77911S]

200k, replace them.

they are pretty robust and it is amazing that the engine will runn pretty good with a bad set of injectors.
I eventually replaced all mine in my 930 with 60k miles.

[Walt Fricke]

diy83 - I've used very thin wire, but haven't developed a technique to do this easily. A hemostat helps. There must be a better way (if you are being paid to do this you'd certainly find a way to make it easy), but I don't know what it is.

I think that after 200,000 miles just the flow of gasoline would erode the valves and seats enough to make the spray pattern be less than optimum. Bosch literature shows ideal (a nice cone), OK (maybe a 3/4 cone), and time to replac (nothing conical there).

[arbita1]

Can anyone confirm if these injectors are the same. I know the blue box works for my model. What about the yellow box.




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[diy83sc]

Looks like same part number. When in doubt, pull the injector and check the part number. This one ends in 004 as do both boxes.

[schoward]

^^^^check the markings on the actual injectors themselves against your current and each other. Just burned up a Christmas gift card getting new ones that came in blue box. Confirmed numbers etched on new ones were exact to existing before install.

[arbita1]

Main part numbers match. It's the other numbers that were confusing. Not sure what they mean. However I went on the Bosch website and it seems these are correct. They fit and look the same. Apparently the 911 and Saab 900 use the exact same injectors.