I removed my upper intake to rebuild the vacuum and water hoses and inspect the EGR. . . . By default, the trailing injectors got removed. .. The diffusers are located right below the injectors.

I noticed the injector diffusers were really gunky.

Anybody have a great idea on how to clean them in place? . . . I need to pull the leading injectors and check those diffusers as well.

Gasoline and a soft bristle tooth brush?

Below are pics.

 

You can technically remove these if you want to clean them. But, be very careful because they don't like being taken out. The plastic gets old and brittle and chances are you're going to break them. I would say rather than cleaning them, just buy 4 new ones. Saves you the headache

 

maybe a tooth pick? if you try to take them out, just buy new ones first, they are going to be really brittle

 

I've had a few adventures with these, so IMO you basically have two options:

- Clean them in-place (just carb cleaner spray and nothing else).

- Resign yourself to replacing them and just buy a new set.

The best thing to do is buy new, since they have o-rings on them that can't be replaced without removing them. I would do this if possible.

If you really need to keep the old ones I would just use carb cleaner and let the pressure of the spray can do the work. Maybe one of those air-duster spray cans would help too. I wouldn't even use a brush.

Trying to remove them is tough, no matter how careful you are at least one breaks and then youre putting in an order anyways so you may as well buy the set.

 

Managed to clean them but one came out really easy. . .. . Not good considering it needs to seal.

Used a fine screwdriver to ream the holes and blew them out from below with an airgun.

Took my time of course.. . . I had the perfect screwdriver size.

The diffuser that come out will need an o-ring. . I'll try to swap the o-ring but you are probably right, just buy a new pair and use new o-rings.

All three plastic legs on both units were still intact so maybe I use them. . . . . I'm trying to keep the shopping cart from breaking the bank.

How easy are the leading injector diffusers to get out?. . . .. I haven't pulled them yet but I am on the verge.

FYI . . . These diffusers and injectors have 302k miles on them and the idle is really rough. . Hence the reason to do this intake rebuild. (engine rebuilt at 263k)

 

Tougher than the secondaries, unfortunately. The primaries are a bit shorter and have two o-rings per diffuser. It makes them fit much tighter in the bore. The way I've removed them is to just push them out from below, but that frequently breaks them as expected.

Unfortunately there's no good way to clean those in place.

 

are these necessary if you swap to modern injectors with a better spray pattern?

 

the Oring is 9954-10-1252

 

If your new injectors are atomizing fuel properly, you shouldn't notice much difference. They will make a differencewith straight spraying injectors. The other important reason these diffuser stacks are there, and why they have 2 orings is that there is a specific orifice in the collar section that bleeds air in during idle. This serves 2 functions. The first is that these allow a specific amount of air to bypass the throttle plates, same as the oil injectors, and provide the correct amount of idle air. The air adjustment screw on the bac is the only adjustable point for idle air. The second function is to keep air flowing past the fuel injectors during closed throttle operation. They are located with the injectors to aid in getting atomized fuel to the rotors with high velocity air. Without these, you will have little to no air movement around the injectors with closed throttle, fuel wetting on the inside of the manifold, and crappy idle.

Hopefully I can finish my vacuum system tutorial videos after Thanksgiving.

 

The new ones I plan to use are the Bosch style rx-8 (yellow) injectors. So what you're saying is I need to have these either way.

 

Only the top portion with the o-ring. Hypothetically you could break off the three legs and the diffuser bit, so you just have the top part as a spacer with the o-rings. This also preserves the air bleed on the primaries. Not sure if breaking that off is better with the new injectors or if it should be left as stock.

Trying to leave this part out won't work, because the injector tip will be narrower than the port in the manifold. These diffusers also function as a spacer.