Bad fuel injector??

[xdan1357]

I got a BMW 316i and there's a problem with it. The car struggles to start and when it does it shakes a lot and the rpms go up and down. Now its even gotten to the point where the rpms dip so low on idle that the car almost stalls. The engine light is on all the time. I almost have no power when accelerating now too. Sometimes its really bad, sometimes i get some power back. I thought its the plugs so i replaced all of them but nothing has changed. The guys that changed the plugs said the cyc 1 fuel injector rail seems loose and when they held it down the car seemed okay on idle and when they released it it got bad. So they think its that fuel injector. So my question is, is it possible one faulty fuel injector causes that many misfires on other cylinders too?? Is it possible its not installed correctly? Also i noticed that a lot of thick white smoke is coming out of the exhaust of the car. What do you guys think?

[328 Power 04]

Maybe... but you'd really need to get the error codes pulled so that you'd have a bit more info about why the car is running the way it is.

[MIKYZZ4]

I agree with Abel,
as a guess via the information you provided, I would replace the fuel injector O-rings.
Update us on what you find.

[xdan1357]

I agree with Abel,
as a guess via the information you provided, I would replace the fuel injector O-rings.
Update us on what you find.

Yeah so i brought it to another mechanic. He said on his diagnostics all that came up are multiple cylinder misfires. Just a bunch of misfires. He said there are 3 reasons for that. Compression, ignition and timing. He started off by doing a compression test, which ended up with cylinder 3 and 4 passing the test and cylinder 1 and 2 being low. He said cylinder 2 isnt as bad but cylinder 1 had really low compression. He continued to say the cylinder 1 fuel injector was really bad. He said it was pumping way too much fuel into the cylinder and the spark plug was even soaked in fuel. Apparently it was also very loose and he could see physical movement of that fuel injector jumping up and down. He also said the tray the fuel injectors were mounted on was straight but by his knowledge it should be bent. He also said the fuel injectors were not coded into the car's system. First thing that popped in my mind was that fuel injectors cant cause low compression in a compression test right? So i told him that but he said my car apparently has a direct fuel injection so they arent mounted to the intake manifold, so they can indeed cause a low compression in a compression test. He said first thing he wants to do is replace that fuel injector 1, and the tray that they are mounted on.
What do you guys think? Does he sound right? Should that fix the problem?
-Thanks for the replies!

[MarcoZandrini]

Compression is occurs when the valves are closed and the piston moves upward towards the cylinder head. Doh! The piston rings on the piston create a near-air tight seal between the piston and the cylinder. A leaking fuel injector (too much fuel) causes “wash down” whereby the seal between the piston, its piston rings is lost. Hence, low compression.
Injectors leak for one of two reasons: they are defective or they are dirty. BMW injectors rarely go bad, so I suspect the injectors are dirty. A dirty injector doesn’t properly atomize the fuel (convert them fuel liquid into very fine droplets), and may not fully shut off. The solution is to:
- get the injectors professionally cleaned
- replace the injector o-rings (each injector has 2 o-rings)
- occasionally add a fuel system cleaner such as LiquiMoly or Techron to the fuel tank
- buy gas that keeps injectors clean.

Here in the US gas stations sell Top Tier Gas (TTG). TTG meets the cleaning standards established by BMW and other major manufacturers. You may have some similar standard in Ireland. I’d see if there’s a BMW car club in Ireland and see what fuels members recommend. Also, I’m sure that there are forums similar to this one in Ireland. Ask the members of those forums.

[xdan1357]

Compression is occurs when the valves are closed and the piston moves upward towards the cylinder head. Doh! The piston rings on the piston create a near-air tight seal between the piston and the cylinder. A leaking fuel injector (too much fuel) causes “wash down” whereby the seal between the piston, its piston rings is lost. Hence, low compression.
Injectors leak for one of two reasons: they are defective or they are dirty. BMW injectors rarely go bad, so I suspect the injectors are dirty. A dirty injector doesn’t properly atomize the fuel (convert them fuel liquid into very fine droplets), and may not fully shut off. The solution is to:
- get the injectors professionally cleaned
- replace the injector o-rings (each injector has 2 o-rings)
- occasionally add a fuel system cleaner such as LiquiMoly or Techron to the fuel tank
- buy gas that keeps injectors clean.

Here in the US gas stations sell Top Tier Gas (TTG). TTG meets the cleaning standards established by BMW and other major manufacturers. You may have some similar standard in Ireland. I’d see if there’s a BMW car club in Ireland and see what fuels members recommend. Also, I’m sure that there are forums similar to this one in Ireland. Ask the members of those forums.

Okay so a quick update. My guy replaced fuel injector 1 and the tray the injector 1 and 2 were mounted on... and now all cylinders passed the compression test no problem. He said the car now runs fine on high rpms but on idle and low rpms we are still getting misfires in cylinder 2 and 3. He said since its not a compression problem anymore, and he swapped around the injectors plugs and coils and problem was the same, its not ignition either. So we are left with the timing chain. He said he can move the chain a tiny bit with his finger and according to him it shouldnt be doing that. It should be super tight. He suspects its jumped a tooth. He will perform a crankshaft test tomorrow or on friday, but before that he wants to change the oil and the oil filter, because he said since that faulty injector was spraying so much fuel, the oil is contaminated with fuel and it could be causing this. Now I dont think bad oil can cause misfires, but its worth a try before we go to the timing chain. Do you guys agree? What do you think?
-Again, thanks for all the replies!!

[MarcoZandrini]

If the engine runs fine at higher rpms then the timing chain hasn’t jumped a tooth. Yes it needs to be tight. There’s a tensioner that can be replaced. Typically, when an engine runs poorly at low revs there’s a vacuum leak. Does the shop have a smoke machine? If not you should find a shop with one as that’s the only way to find all of the vacuum leaks.

One last thing, please post the last 7 characters of the car’s vehicle identification number. Your car is an E90 and that chassis was built for many years and underwent many changes.

[dworthy]

Well if the CCV is working properly, then yes fuel vapors are being burned, which can cause a rich condition. You will see this in the STFT and maybe in the LTFT if the tech is looking at live data.

Also since the E-46, BMW hasn't produced a 4-cylinder motor that is worth a squirt. The main issue is the timing chain, would have been better off using a belt, as most of them wear out under 100k miles and need to be replaced.

So long story short, if he can move the chain with his finger, then get it replaced as well as the guides.