2008 E90 320i Misfire/Rough Running Issue

[mbwoy84]

Well, as there was so much good knowledge on here in helping to cure the ASC issues with my E38, I thought I'd see if anyone knew much about the E90.

I bought one a while back very cheaply. 2008 320i M-Sport. Nice car, nice spec, with FSH and mint inside and out considering it's just gone over 100k.

Anyway, I picked it up cheaply as it was running very roughly. Flashing EML and shaking under acceleration. Now I know these 4cyl engines are known for coil and injector problems. I read the codes on a full fat diagnostics machine and there were quite a few, so cleared them first and a few kept returning, most notably "Combustion Misfire Cylinder 2".

First thing I did was check the plugs and coil packs. Plugs looked well due for a change (FSH car, but plugs not changed on the last 2, so due now anyway) and Coil packs didn't look too healthy. The plug and coil in cylinder 2 did look the worst. So changed all 4 plugs and coils and the engine seemed to run better than it did, but still misfiring.

Anyway, after clearing the codes again, upon starting the car, three codes appear almost immediately every time. These are:

- 2E30 - Fuel Injector Cylinder 1 Activation
- 2EF7 Map Thermostat Activation
- 2F11 Radiator Blind, Top

Now in terms of cooling I think one of the codes from when I first read the car related to the electric coolant pump if that's another clue as there are radiator/thermostat codes showing.

Additionally, I have read on various forums that there was a recall on these cars for injectors and they updated them. There are 2 outstanding recalls showing on this car, but I don't think either of them relate to injectors from what I can gather from researching the recall codes. Surely I'm not going to get that luck that BMW will change all the injectors for me?!

Otherwise I can order a new injector, but if this is the new type, would that not work correctly with the other 3 if they're the old type? Or vice versa. How would I check? Hoping someone has some knowledge of these engines and their injectors!

Additionally I have carried out a compression test just in case, sort of, in as much as it looks like you need a longer adaptor to suit this engine. I managed to get my hands on one which was longer than what I had, but still not ideal, so had to hold it in place. I got readings of around 110psi on ever cylinder, so which seems low, but the fact that they were almost identical on every cylinder would lead me to hopefully believe that with the right adaptor I would get higher readings and the fact that the readings were consistent across all cylinders would suggest that there was nothing untoward, but just thought I'd add that just in case I'm wrong and low compression across all 4 may point to something else.

Hoping for some wise knowledge in anticipation!

[helix402]

One new injector will be fine if that’s the cause of the problem. A new injector needs a new decoupling element. The code also needs saving to the DME. Special software is needed to do this.

Re the codes, the thermostat one means the thermostat is faulty. You have an N43 engine.

[mbwoy84]

I can code injectors, no problem there, but wasn’t sure if there was an upgrade on the injectors, fitting one which was the upgraded type along with 3 which weren’t would cause an issue.

Would a faulty thermostat possibly throw up the radiator blind fault? I’m pretty sure the car doesn’t have a radiator blind fitted, but will look tomorrow. An online search shows that this fault code comes up a lot as a “bogus” code on cars that aren’t fitted with them, but guess it’s more likely to come up along with a genuine code in the same area.

[helix402]

The injectors are updated, some say one later type will cause problems if fitted with the older type. I’ve fitted single later injectors without problems.

Rad blind fault is probably a red herring as you suggest.

[mbwoy84]

Right, well I've ordered a new injector and new. See what that does. I've left the water pump for now as that's not a code which shows immediately now, so hopefully if that cures the problems then I can start putting a few miles on the car and re-read the codes later and see if anything is still there.

Also booked it into BMW for 2 weeks time for 3 outstanding recalls. One for a new positive battery terminal/cable, one for heater blower and one for something to do with OBD software.

[mbwoy84]

Well, I ordered a new injector and thermostat earlier from Euro Car Parts and before they cam, I had a quick look at the injector in readiness to take it out and spotted that the wiring to it was unplugged and tucked away down below so it wasn't easy to spot without looking closely. It's obviously been like that since before I got the car and someone had been playing about with it. Plugged it in and it runs and drives A1 now, with no warning lights and no misfires.

I had re-read the codes after driving as it's the first time I've ever driven it any real distance and it still comes up with codes relating to Coolant Pump and thermostat. The Coolant pump one seems to come up first. When reading up on this previously some people seemed to suggest that it was common for the wiring to the coolant pump to fail/become damaged, so wasn't necessarily the pump itself. Just wondering if that would be connected to the thermostat as well, as that code doesn't come up always now and certainly not before the coolant pump one and there are actually two codes for what looks like the same thing. Plus they are very closely connected in the car.

- 2E84 - Electric Coolant Pump, communication
- 2EF7 - Map Thermostat, activation
- 2E85 - Electric Coolant Pump, communication

[bmwmike]

Haha nice easy fix. Wonder how that came to be unplugged.

[mbwoy84]

My guess would be that it starting misfiring due to a dodgy coil. Someone started playing around with it and possibly looking at injectors and ended up unplugging it and forgetting to plug that one back in. Either way, it all seems sweet now anyway fingers crossed.