[Phil325i]

Jet if you've not already seen it, this video helps you understand how to code the injectors:

http://www.e90post.com/forums/showthread.php?p=18457619

It seems the jury's out as to whether coding makes any difference or is even necessary. My local BMW master tech says he's never coded an injector. Apparently the injectors quickly 'learn' once fitted. This was borne out when I changed my injectors. I did code the new ones in, but it was obvious that the injectors I removed had never been coded.

[Jet1990]

I believe the car has had some injectors changed under recall so potentially they were never coded

[Jet1990]

Just come across this little bit of info on another board

I've had more than my fair share of pain with the N53 530i and so far managed to fix it every time, so I may be able to help. From your description of a problem that only occurs on cold start - it's always been a problem with an injector. If you take to a BM dealer they will say the only way to fix this is to change all the injectors and may well say change the coils and plugs as well - that WILL fix it, but it will cost plenty.

On mine, I have found that the when the DME diagnoses a misfire on one of the cylinders, it's never been the cylinder that misfires that is the cause of the problem - I have a theory about this.

First of all - the engine ECU (DME) controls the engine as two banks of 3 cylinders, the front 3 are controlled based on one exhaust O2 sensor, the rear 3 are controller based on another O2 sensor. These O2 sensors are quite advanced, they are 5 wire known as broadband sensors and they heat up very quickly indeed - the DME starts controlling the fuel mixture based on O2 readings about 5 seconds after start-up. You may notice on a cold start that the engine initially appears OK for a few seconds and then starts to misfire - that is when the "closed loop" control starts and the O2 sensor detects low O2 in the exhaust.

So what is happening? Once your engine has started, the DME detects low oxygen in the exhaust (running rich). It responds by leaning off the fuel mixture of all 3 cylinders at the same time as it does not know which of these cylinders is responsible for the rich mixture. When it does this the first cylinder to misfire will be the one that was running leanest due to a action known as "lean cut". In your case cylinder 3. So your ECU diagnoses a misfire on cyl 3. The problem will almost certainly be with one of the other two cylinders (1 or 2) whose injector is not closing properly and administering too much fuel. The faulty cylinder will not misfire as the ECU leans the mixture as it was already running rich.

Hopefully, you've kept hold of the injector you took out of Cyl 3. It's now a game of chance as to which cylinder to try next. If you have the GT1 software you can take an educated guess by looking at the smooth running parameters of all 6 cylinders at the same time, the one with the most positive value after a cold start is probably the one. Failing that - take a guess, it doesn't take more than a 10~15 mins to change the injector. Try your original cyl3 injector in one of the other 2 cylinders, if it works great, if not try again and you'll be sorted.

In all this - I assume you are using INPA or equivalent to re-code the injector you change and then use GT1 or INPA to reset adaptations?????

Two top tips
1) When changing the injector - lock your car once the bonnet is open, this stops the DME from occasionally re-pressurising the fuel rail and spraying fuel out.
2) When resetting adaptations - don't press the brake pedal when you press the start button next. You want the ignition to turn on without the engine for the first 10 seconds as it needs to re-learn the throttle body servo.

[Jet1990]

Heres what the old injector looked like when i took it out

[Dormermike]

Pity they can't have new nozzles fitted. Exposure to combustion process can't be good for a pecision instrument. Especially if a cylinder is running lean due to an adjacent rich condition.

[old grey steve]

Originally Posted by Jet1990

Heres what the old injector looked like when i took it out

Looks fairly well carbon'd up Jet which is to be fair what I'd of expected from one of these the thing with these as I stated earlier is the longer they are left the more problematic the knock on effects can turn out to be namily one known injector being supported by another injector(s) only for one or more of these to sucombe to failure as they've been playing a nursemaid to a defective injector for some time. But if you're replacing one you'll discover whether everything is stable once everything is in place and coded accordingly and a smooth running test can be verified.

Prey you get the issue solved with the new injector alone. Re coding we always always run this procedure seen some of the alternatives but fir us we always follow specific coding procedure via diagnostic

[Phil325i]

I now realise how bad mine were! The whole of the cone end was thick black on mine...

[Jet1990]

New Injector is in and coded using the snap on verus. Problem still there in the morning misfire cylinder 2 along with a "fuel pump plausability " error code

[Jet1990]

To add to that, i ran through some parameters yesterday on the diagnostic tool and it gave the following...
low pressure fuel sensor - 62 psi
high pressure fuel sensor 2879 psi
coolant temp 110 degrees c
engine oil temp 106 degrees c
MAF 12 kg/h

so as it stands ive swapped out injector two to no avail so im going to have it properly coded with inpa and investigate the neighbouring cylinders at the weekend.

[Dormermike]

As someone said above though the problem could be an adjacent cylinder on the same bank. Apologies if you tried that already.

I had a separate thread about my car same engine and it went in with cyl 2 misfire, replaced injector etc and the misfire moved to cyl 6. They replaced cyl 6 injector and the misfire popped up somewhere else. In the end the dealer opened a puma case as they've "never seen this before" (lol) and BMW said to replace all injectors so I now have 2 new coils and plugs and 6 new injectors. Got dealer to warrant the injectors for 2 years.

I did try to keep the old injectors but they wouldn't let me. I doubt all were dead. I want to try and soak the nozle end in Mr muscle or similar. Anyone tried that?

[Jet1990]

Originally Posted by Dormermike

As someone said above though the problem could be an adjacent cylinder on the same bank. Apologies if you tried that already.

I had a separate thread about my car same engine and it went in with cyl 2 misfire, replaced injector etc and the misfire moved to cyl 6. They replaced cyl 6 injector and the misfire popped up somewhere else. In the end the dealer opened a puma case as they've "never seen this before" (lol) and BMW said to replace all injectors so I now have 2 new coils and plugs and 6 new injectors. Got dealer to warrant the injectors for 2 years.

I did try to keep the old injectors but they wouldn't let me. I doubt all were dead. I want to try and soak the nozle end in Mr muscle or similar. Anyone tried that?

Going to take a look this weekend at the neighbouring injectors. I homed everything in injector 2 and now that it hasn't solved the issue im scratching my head. I'm hoping its just a case of having to recode the new injector even though i did it with my scanner, I'm going to get it done with INPA

[Jet1990]

Got INPA up and running yesterday, now although im pretty clued on with my snap coder i knew i had to tread carefully with this. First thing i did was to check if injector 2 ( the newly replaced one) was properly coded to the car in which it was so i cant fault the coding as the reason for the symptoms still showing.

attached are two pictures of the rough running figures - one from last night when the car was running as normal and one this morning after about 1 min of a cold start ( note cylinder 2 figures have entered the red area)

also, whats i find odd - with the car running and hooked up into INPA, as the EML came on and went into a misfire mode i cleared the fault codes in which the light turned off and the cylinder was running normal and then about a min later light came back on and misfire occured. It seemed that i had to physically turn of the engine and restart it to keep the light and misfire coming back.

[Jet1990]

Took the spark plugs out in the bank today before driving it anywhere. The plugs are all in the same condition with no visible sign of wetness. Pretty stumped as to what the issue may be now.

[old grey steve]

Originally Posted by Jet1990

Took the spark plugs out in the bank today before driving it anywhere. The plugs are all in the same condition with no visible sign of wetness. Pretty stumped as to what the issue may be now.

May sound way off the beaten track this...... But if the misfires there and you've exhausted what you feel is all options and if all routes re looking at injectors have a look at a compression test sounds awfully old fashioned but there are times and we've seen it where old school actually pinpoints the issue perhaps a tad more so when cold.....usually if something is found you can look at the series of events and perhaps what may/could of happened but it might be IMO now be worth exploring this as it does take too long really to do especially if it's still cylinder 2 specific and you have explored all other routes. Sounds drastic but yes seen a few modern lumps with issues relating to compression.

Other areas can centre on looms and ECU's you're looking for pin issues such as corrosion and loom break down, but these are shall I say rare.

[Jet1990]

Originally Posted by old grey steve

May sound way off the beaten track this...... But if the misfires there and you've exhausted what you feel is all options and if all routes re looking at injectors have a look at a compression test sounds awfully old fashioned but there are times and we've seen it where old school actually pinpoints the issue perhaps a tad more so when cold.....usually if something is found you can look at the series of events and perhaps what may/could of happened but it might be IMO now be worth exploring this as it does take too long really to do especially if it's still cylinder 2 specific and you have explored all other routes. Sounds drastic but yes seen a few modern lumps with issues relating to compression.

Other areas can centre on looms and ECU's you're looking for pin issues such as corrosion and loom break down, but these are shall I say rare.

A strange little thing happened today. Started the car, no issues...no rough idling and no misfire. Could this be due to a warm morning ( 20 degrees c in the shade)

[old grey steve]

Originally Posted by Jet1990

A strange little thing happened today. Started the car, no issues...no rough idling and no misfire. Could this be due to a warm morning ( 20 degrees c in the shade)

Stranger things have happened however don't take it all's well I'd still look in to things

[Jet1990]

Just abit of an update. Had all 6 injectors and coils replaced over the weekend and the misfire is still there so the cars gone back to bmw for further investigation, sigh.....

[Dormermike]

Looking forward to hearing what they find. Mine had six new injectors recently and I was on a 2hr drive today and I could feel it missing when I was cruising. Under load it's fine.

[richk84]

Which dealer has it gone too?