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Got this one for not very long. It's a 99 A4 2.8 AHA. was suffering rough idle, misfire and low responds on low rpm. I checked couple of things: coil pack, spark plugs(new), and fix some crack vacuum hose, and a loose cam sensor connector. Car's getting better. but still get some missfires while traced by vag-com. then check the fuel system, first, No 3 injector top o-ring has a leak. So I decided to do a fuel system tune up. fuel filter and o-ring plus fuel injector cleaner in fuel. I first changed the fuel filter, that's harder than I thought, took me 2hours, this car's fuel filter must never been changed, muddy fuel in both side of filter, unbelievable, the car still runing.

So I suspect fuel injector gonna very dirty. I was right,I removed the fuel rail with injector, and did a injector test(our vag-com has such function), injectors spray pattern was nightmare even after change the fuel filter. without doubt a injector flush is necessary. So here I come.

I did some research, here is a good article Ford Fuel Injection » Fuel Injector Cleaning but wasn't complete apply to me as I don't have compress air. So I use vacuum instead.

My injector is 078-133-551L(216cc@3bar 15ohm 21lb/hr) which made by siemens instead bosch. but things are very similar. same size O-ring(7.52x3.53mm) and same size micro filter(6.07mmx12mm) which you can order from ebay for cheap.But I don't have time to wait, so change o-ring and flush injector only.

1. take out injectors from rail by remove the clips, mark them for installation to original place.Remove the o-rings on both head. clean the surface by brake cleaner and a brush.

2. buy a bottle Injector cleanner, any brand, about half - one liter. soak the injector in about 1-2 hours or more, if you have ultrasonic cleaner, that'll faster, about 15-30mins enough.

3.build you own injector sucker system, You can see the picture, a brake bleeding system and a remote starter switch. power source could be a battery charger or just a 12v digital switch type PU, don't use analog type as empty load voltage may too high.

4.take out one injector from dirty fluid, clean and dry. and hook it in the system you build in 3. just like you bleed your brake. first test by 5mmhg, see if there's leak, then raise to 15mmhg or 20mmhg. then suck clean injector cleaner fluid from another container by press and release the switch intermittently till to clean fluid pass by for few second. then take the injector out, and make a vacuum to 15-25mmhg again, press and release again to such air till tube dry, this just for clean the fluid out of injector. Do each after.

5, put the new o-ring one with light clean ATF or engine oil. which just make installation easier.

6. install back and do a injector on car test again, You'll see quite difference. check leak and install back.

Now, my car's idle and low rpm responds are great, and gas millage improve quite a lot.

Use this information on your own risk, Good luck.

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