The Coupe Quattro
Ongoing Restoration
Info / Data

Audi Type 85 Injector cleaning

By Todd Miller

Remove the big rubber boot over the sensor plate on the air filter housing. Be careful not to break any of the plastic fittings!

Pull all of the injectors and remove them from the lines. Spray them inside with carb cleaner and then tap them repeatedly, upside down onto something like a piece of wood. This will dislodge a lot of the crud in them. Keep spraying them out and taping them.

Next, pour a little bit of ATF in them and put them back on the fuel lines.

Jump the 2 large connectors that are perpendicular to each other at the fuel pump relay. Remove the relay to do this. This will power up the fuel pump and pressurize the system.

With the injectors laying on top of the valve cover, lift the sensor plate using a magnet or a pair of needle-nose pliars grabbing the center bolt head. As you lift the plate all the way up (full throttle position) the injectors should produce a nice rotating fog pattern, and they should "sing."

Any injector that doesn't do this needs to be cleaned better. So first, while the injector is spraying, smack it with a small wrench...like a 14mm open end. As you smack it, the pattern will improve. If it doesn't completely improve and begin rotating, remove that injector and do the carb cleaner, tap out the crud, fill with ATF trick again.

Once cleaned, they will fog, rotate and "sing" at any position of the sensor plate.

Remember, you don't need to have a perfect spray pattern in order for the engine to run. So make sure you don't have other issues keeping the engine from running.

As a final note, whenever you remove the injectors, you should replace the o-rings on them. Otherwise you'll end up with a monster vacuum leak around each one.

A footnote....

There's a rotating goody down inside the tip called a "pintle." There's also a screen. Once the screen gets clogged and/or the pintle stops rotating and vibrating (which is what makes them sing) you get injectors that are peeing in streams rather than fogging.

All sorts of poor performance and driveability issues are the result and if the injectors get bad enough, they will sit and drip when hot. This causes major hard hot starting because the carbon on the backs of the intake valves and tops of the pistons becomes a sponge soaked with fuel....totally flooded engine condition.

But, the ATF/Carb cleaner/full throttle sensor plate/tapping on them trick works wonders.

Follow it up with a full can of BG44K injection cleaner (get it on ebay) in about 1/2 a tank of fuel.

One word of caution. You're spraying atomized fuel!!!!! Don't set yourself or your car on fire!!

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