[T3mp0]

To start off I have on order a Carly adapter, But I bought a 2008 bmw 335xi with 118k miles for cheap knowing it had a few issues, but am stumped at this point. Bought new coils and spark plugs due to a few misfires. Fixed the misfires but I have a mild misfire at startup. goes away when high idle comes down. Then while driving at about 2k rpms feel a kind of a rough misfire and get a engine malfunction with reduced speeds. Only codes are P0420 and P0430. I have replaced the upper O2 sensors but due to a broken bolt on the downpipe I am going to go in and have them replace the lower 2 O2 sensors. When I bought the car though it did not go into engine malfunction low power. So I am unsure as to why this is? I checked the gas cap and put in fuel cleaner.

2nd problem being the overheating. The engine fan only turns on when the AC is on. Without the AC on it never turns on. I unplugged it which sent it into high fan mode. I read that it could be a coolant temperature sensor. so I replaced it. No luck. Also tested the water pump while off and could hear it operate. Any help and I would be grateful. These cars parts are too expensive to throw parts at it.

[arkie6]

Rough idle at startup could be leaking fuel injectors. That was my problem with my 2008 335i. New index 12 injectors fixed it. Check your fuel injector index numbers to see if they are original or prior to index 10 (index 12 is the most recent). You can check for leaking fuel injectors by removing the spark plugs after an extended run and cooldown for at least an hour. If any plugs are wet, you most likely have a leaking fuel injector on that cylinder. You can also use an inexpensive bore scope that plugs into your smart phone to take a peek into the cylinder after the spark plug is removed. If you have any visible fuel on the piston or fuel pooling between the low edge of the piston and cylinder wall, you definitely have a leaking fuel injector.

Another thing that comes to mind is carbon buildup on the intake valves is very common on higher mileage N54 engines due to the PCV system design and lack of fuel spray on the valves due to the direct injection. The carbon buildup can get very heavy. The most common fix for this is walnut blasting the intakes. If you are not familiar with this, google it. It is a common problem with direct injection engines.

Does your car have aftermarket down pipes without cats? If so, that is the likely cause for the P0420 and P0430 codes (catalyst system efficiency below threshold, bank 1 and bank 2).

[T3mp0]

How would I check the index of the fuel injector? I still have the cats it appears, any advice on the overheating? I am going to look into the fuel injector issue.

[arkie6]

Originally Posted by T3mp0

How would I check the index of the fuel injector? I still have the cats it appears, any advice on the overheating? I am going to look into the fuel injector issue.

https://www.e90post.com/forums/showthread.php?t=1425620

I've never had to deal with overheating issues. I did have to replace a leaking waterpump and failed coolant hose connector though, but these just triggered a low coolant warning and I caught it before the engine got hot. What are your symptoms of the overheating? How hot is your oil temperature running?

[arkie6]

More photos showing injector index number:

[T3mp0]

Thank you for the reply!, I haven't been able to check the injectors yet, I was working on the girlfriends 69 beetle, and since the BMW is more of a fun car for me I put it on the back burner. My overheating happens only when sitting still and with the AC off. With the AC on my fan works. I noticed it because the far notified me of the coolant temp being over 103. to recap I know my fan is not working when the coolant gets hot. I don't wanna throw parts at it. I have replaced my coolant temp sensor below the oil filter on front of engine.

[Bombed321]

I have a 2011 bmw 335i n55 e90 I am having an issue with the car overheating and going into limp mode I've replaced the coolant reservoir, thermostat, a upper radiator hose, and a temperature sensor I've also run a radiator stop leak through it. I have no idea at point

[arkie6]

What codes do you have stored? How many miles on it? Have you replaced the electric coolant pump? Has it ever been replaced? Why did you run radiator stop leak through it?

[Tyc0]

I'm the regard to the overheating, I bet money your water pump is failing. Mine did the same thing, always get overheating engine light on farther drives, but I tested the pump while the car was off and it sounded healthy. Long story short I replaced it and problem solved. Second thing you could check is your battery, these cars start to act weird when they don't have the right amount of power.

[DRUBIO]

Very interesting Tyc0 !!
I have a 330i 2006 with 65K miles on it with the overheating. And is driving me crazy !!
Every other week (more or less) the car shows the overheating sign on dash (yellow) if I keep driving after a couple of mins. turned to "Red". I have replaced the thermostat, water pump, exp tank, coolant etc. but still having the problem with no OBD codes, after several things I realized that when shows the overheating sign I pull over disconnect the fan harness and re-connect it back and the fan start running like crazy and after several secs turns to idle, AC works and the car gets into normal temp. at least until next time. Do you think it's a battery issue ? I do agree that these cars check batt life and act weird if it's not a 100%.

[DRUBIO]

Any Help will be much appreciate it !!

[DRUBIO]

Very interesting Tyc0 !!
I have a 330i 2006 with 65K miles on it with the overheating. And is driving me crazy !!
Every other week (more or less) the car shows the overheating sign on dash (yellow) if I keep driving after a couple of mins. turned to "Red". I have replaced the thermostat, water pump, exp tank, coolant etc. but still having the problem with no OBD codes, after several things I realized that when shows the overheating sign I pull over disconnect the fan harness and re-connect it back and the fan start running like crazy and after several secs turns to idle, AC works and the car gets into normal temp. at least until next time. Do you think it's a battery issue ? I do agree that these cars check batt life and act weird if it's not a 100%.