I've been chasing intermittent injector leaks practically since I bought my 924S. I kept thinking that it was damaged O-rings. A couple of months ago on another forum I saw a vague reference to injectors leaking in the body. When I took a close look at the one that was leaking I discovered that the nozzle turned in the body of the injector... very easily.
So I bought a fuel rail with 4 injectors off eBay, replaced the problematic one and voila - no leak. Then discovered that another of mine was leaking, took it out and the nozzle was loose in it too. One of the four that I bought had some sort of brown sealing compound residue above the nozzle / injector body junction... guess what, that one turned too.

I don't know if there are other places the injector body leaks but before you start changing O-rings give the nozzle a little twist.

 

can you post a pic of what you mean by nozzle?

 

The silver part that carries the O-rings and sprays the fuel.

 

interesting. Thanks a lot. I had a set of injectors on my NA that I ended up replacing because they kept leaking even after I rebuild them thinking it was just an O ring. I thought I damaged them during the rebuild but I think my issue was the same one you described. As a matter of fact I still have that set of injectors, I'm about to go check them out...

 

You could have just bought the plastic cups and O-rings they get old and brittle when you say leaking unless your intake is pressurized a fuel leak won't be visible from the pintle area with the injector installed you might have vaccum leak around the injector. I just put brand new injectors in with new O-rings and I can still turn the after they were installed. The sealing compound was prob used to try to seal up a vacuum leak from old O-ring or a cracked cup.

 

I did replace both the O-rings and the pintle caps and still had an intermittent leak. The the injector can turn once installed (it would turn within the O-rings), my problem is with the silver part (that I call the nozzle) turning vis-a-vis the body of the injector when it is not installed. It is crimped in place and if it comes loose I don't see how pressurised fuel cannot leak out through the resulting gap. Perhaps I don't understand the internals of the injectors though.

 

If you can add ballast resistors to the newer style EV6 injectors I think those would be a better option. I run them on my 968 and one of my 928s however they use high impedance stock. The EV6 injector I feel has a better pattern and the body is less prone to leaks.

0-280-155-865, Ford 24 pounders, might work well with ballast resistors for the 85.0 cars. Maybe late 944 as well? 0-280-155-923, Caddy or late Jeep 4.0 might also be a good choice.

There can be drama (fire!) with the injector clips also, clips should be used or some other means to secure the injector to the rail. You can cut new grooves into some of the EV6 injectors, or harnessing the injectors to the rail with stainless mechanic's wire will work well if done properly. The GM version of the clip can also be investigated, for the 944 the groove position would be different and it might align with the groove in some of the EV6 injectors. Stock 944 clips can be found more cheaply as a BMW part.

-Joel.

 

944 NA doesn't need resistors...NA uses low-z 2.4-2.8ohm coil like lots of other cars.

 

Winner winner...my old injectors also spun. Had no idea about this failure mode. Thanks for the info Elgy.

 

I didn't know about this. So how does this problem manifest, as a misfire? I'd like to take out my NA's injectors and check them, that car has a slight miss when it's cold.

 

The only manifestation I've had is the gas leaking around the injector.

 

Shprtly after pulling my 944 into the garage , I pulled the decrepit things out of the rail and sent them to a local rebuilder for checkout . $100.00 later he told me they were total junk. So since I work at AZ I ordered replacements . I think they are GM and fit some model of Buick. I checked further with our supplier who told me they would work . I haven't tried them out yet, since the engine is still out of the car..nice to know about the resistance levels so I'll check further . I'm open for comments Thanks.

 

I'm interested to see if those injectors are really the same or not. If so, that would be a good find!