lakoe

As mentioned above i replaced 3 fuel injectors on my 2008 audi S5 with the magnesium manifold and once put back together and i go to start it, it starts normal and then the rpms go very low and jump and the car sounds very off and is struggling to stay on. The lights inside the car flicker a tiny bit and the dash lights are very slow to get to full brightness so i thought it might need a little jump so i tried hooking up the battery and same thing. Any ideas or help would be much appreciated!



https://imgur.com/a/LLvWSgW

hahnmgh63

I have to ask, when you pulled the injectors, did the end seal come out with it on all 3? You used a new Injector seal kit? Did you use the tool for enlarging the Teflon seal? If you don't use the tool you can easlily deform the Teflon seal.

lakoe

by end seal are you referring to the o rings? if so i replaced all 4 o rings with new ones and oiled them up with brand new oil, so not technically a new seal kit but new o rings. I know the teflon seal is the white circle at the end and i didnt use any special tools for removing or installing the injectors.

https://injector-rehab.com/wp-conten...10/GDITool.jpg is this what enlarging tool youre talking about?

hahnmgh63

Audi Workshop Service and Repair Manuals > A4 Mk3 > Power unit | Direct injection and ignition system (4-cyl. 1.8 ltr., 2.0 ltr. 4-valve turbo - generation III) | Mixture preparation system, electronic inj.,Gas | Injectors | Removing and installing FSI injectors (workshop-manuals.com)
In the 3rd image down of the injector it is part #3, new they are white but used they can definitely look dirty. They must be replaced along O-rings or you can get a combustion leak at the injector.

lakoe

i see, that is the teflon seal and it was never removed from mine when i removed them and installed the new ones. do i 100% need new ones? car is back together and wasnt running right at first but its running and starting good now.. but i did a pull now i have p0171 fuel system too lean and cylinder 1 and 5 misfire.

hahnmgh63

You are supposed to replace them anytime the injectors are removed. I have never not replaced them as the Repair manual says to replace them so I can't say 100% that's your problem but they are obviously not 100%.

lakoe

so if i just took out the new injectors that had old o rings that i reused and replaced them with new o rings and put it all back together, if i went back in once again and removed all 8 injectors would i have to re replace the 4 o rings i just replaced and the other 4 o rings on the other side AND all 8 teflon seals?

hahnmgh63

If you lubricated the O-rings with motor oil (per the service manual) then they should be fine in this short of time. Hopefully you didn't force the Injectors in with dry O-rings as that can cause them to roll or tear.

lakoe

i lubricated them the second time with fresh oil, the first time no... but the new o rings did have oil in and went in smoothly. im thinking i might have to go in again to replace the two gaskets and the other 4 o rings and maybe the teflon seals. not sure yet. as i still get cylinder 1 and 5 misfires as well as fuel lean codes.

lakoe

i saw a video on youtube once saying that if youre car is running and the oil cap has a lot of suction while trying to remove it needs a new PCV, does anyone know if this is true and applies to the magnesium 4.2? because if i remove mine it not only has suction but when i get it off the car almost dies and drops rpms heavily..