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Discussion Starter #1
I would like to share my experience with the N53 engine and how I dealt with all the troubles I had so far.

Lumpy idling and rough running were the first symptoms of the bad injectors in my case. For the first few months car would sound like a bag of nails on the cold startup for the first few seconds, then it was fine.
No error codes or any other symptoms after driving off.

I ignored the problem until the car started throwing Engine Management Light on cold startups and showing Misfire on Cylinder 2 code. Along with Fuel Mixture codes.
Took the car to the BMW specialist and they diagnosed a faulty injector on Cylinder 2. Warrantywise agreed to pay out for 1 injector but this is where their kindness ends.

Garage advised me that replacing one injector is not a solution to the problem and all 6 injectors need to be changed (£1700 job).

After replacing one injector car was absolutely fine for a week. Stady idle on cold startup and no vibrations.
After a week everything went back to where it was. Every single cold startup resulted in EML on, error codes, vibration and rough running.

What's weird is that I got the exact same error codes after replacing an injector on cylinder 2 i.e: misfire on cylinder 2. In my opinion the only way to deal with this is to replace all 3 injectors in bank 1 (cylinders 1-3).
So I ended up buying 2 indexes 11 injectors off eBay and installing them myself.

During installation:

49436051_1201572890018469_2390138386712100864_n.jpg

Some oil found?
The car used 1litre of oil in 10k miles so I don't think I've got a major oil leak somewhere?

49688591_2060583167360298_91501495102472192_n.jpg

Injector 1 out:
Not too bad for index 8 and 10 years?

49808809_1184352458390545_5465585371536424960_n.jpg

Injector 3 out:
Looks bad and the injector was covered in oil:

49673996_2351996011703396_7211573333517664256_n.jpg

I put two new injectors in, coded them using INPA and everything is fine... so far.

The installation process was very easy. Took an hour all in. I used YouTube videos as guidance.

Started the car this morning after 15 hours and in 5C temperature and the idle was steady. Did not move until it reached idling RPM.
This could be temporary so I'll report back here in a week.

To sum up, the car is now running 3 injectors index 8 on bank 2 and 3 injectors index 11 on bank 1.

The main reason I decided to post here is to show that replacing injectors on those engines does not have to mean a £1500+ job.
I know I still have to replace the remaining 3 in bank 2 but even then I'm looking at around £700 for all 6.

Keep an eye on eBay and Facebook because the new injector does not have to be a £160 expense.
 

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On your oil leak, difficult to see from the pic, but could be overspill from the oil filler (or a filler cap seal gone) or (more likely) a hairline crack in the valve cover. Worth doing a thorough inspection of the cover plastic with a bright inspection lamp to identify any cracks...
 

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Discussion Starter #7
I don't suppose you bought off this seller did you?

https://www.ebay.co.uk/itm/GENUINE-...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

I bought 1 for £110 over Xmas as ebay had 15% discount code and the buyer accepted my offer of £130.
I have 3 index 11 fitted and just 1 older version remain in engine.

But if you had warranty for 1st injector why did you payout from pocket for 2nd and 3rd injector.
No it wasn't that one.

The warranty, I've got is with Warrantywise and they agreed to only pay out for 1 injector.
Even though the garage strongly advised replacement of all 6, the warranty company don't go by 'recommendation'.
They only cover 'sudden mechanical failure' which is not the case with all 6 injectors.

In the end, I didn't bother with the warranty because the entire process was painful for everyone involved; me, garage and warrantywise.
 

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Discussion Starter #8
On your oil leak, difficult to see from the pic, but could be overspill from the oil filler (or a filler cap seal gone) or (more likely) a hairline crack in the valve cover. Worth doing a thorough inspection of the cover plastic with a bright inspection lamp to identify any cracks...
I had the BMW specialist to do a compression and smoke test and they found a tiny crack in the valve cover.
I wiped all the oil off the cover when I was doing injectors and I'll recheck it again next week. Hopefully, there won't be any oil deposits.
 

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I had the BMW specialist to do a compression and smoke test and they found a tiny crack in the valve cover.
I wiped all the oil off the cover when I was doing injectors and I'll recheck it again next week. Hopefully, there won't be any oil deposits.
Hmmm. If it's cracked, it's cracked. The leak won't go away unless it's repaired (or you fit a new valve cover)...
 

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Discussion Starter #10
Hmmm. If it's cracked, it's cracked. The leak won't go away unless it's repaired (or you fit a new valve cover)...
I don't know If I'm going to bother to be honest because the car used 1l of oil in 13k miles (1 year since it had the service) and I've done mostly short trips and town driving.

I'll take the engine cover off tomorrow and see if there is any oil deposit between injectors like it was last time.

After one week of having the injectors done I noticed some things. First one is the smell of petrol inside the car after leaving it overnight. Nothing major because even my wife said she can barely smell anything but it's there. I think when I undone the fuel lines some petrol might have gone over or through the cloth and sprayed over some plastics and it's still there.

And another thing...

When I start the car up in the morning after around 9-10 hours since the last use, the idle goes up to around 800rpm and then slowly drops down to idling speed (600?). But if I drive the car for a short period of time like 10min, turn the engine off and then on again after around 2 hours, the idle goes up to 1000rpm and then slowly drops down to idling speed. Obviously once a engine is warmed up, it starts up at 600rpm as usual.
 

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Your fast idle when cold issue is normal. Mine does exactly the same. When stone cold it initially gives a burst to 1100 rpm then drops to normal warm idle speed. Stop the engine 5 mins later and restart however, and the engine does what I would call a 'proper' cold start (higher initial revs and maintaining around 900-1000 rpm until warm). It's baffling, but having tried everything I can to solve it, I've come to the conclusion it's a software issue and I've had to learn to live with it...
 

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Discussion Starter #12
Your fast idle when cold issue is normal. Mine does exactly the same. When stone cold it initially gives a burst to 1100 rpm then drops to normal warm idle speed. Stop the engine 5 mins later and restart however, and the engine does what I would call a 'proper' cold start (higher initial revs and maintaining around 900-1000 rpm until warm). It's baffling, but having tried everything I can to solve it, I've come to the conclusion it's a software issue and I've had to learn to live with it...
Thank you. I wasn't sure if this was normal and after owning N53 for a year I'm a bit paranoid.

I posted earlier about the fuel smell in my car. Turns out I left my old injectors in the open top box in my boot. Old injectors = strong fuel smell.:sarcastic Silly me.

So far car performs faultlessly. Cold startups are smooth and there is no hesitation in mid range when accelerating. No error codes stored either.
 

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Glad all is well:)
 

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Well at leased you haven't had problems like me 1st engine rough idle so I bought 6 new injectors then i got headgasket symptoms coolant loss 2k for a new headgasket 1 week later same problem engine removed and stripped found a crack in cylinder 6 buy a new engine as a good will the garage will fit it for me for free 1 week later knocking noise engine removed and stripped 5 rod bearings and crank knackered spent nearly 5k on it and it's still in bits and I need an engine again ultimate driving machine
 

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I must say that it is an interesting findings Mahoone. You found a misfire on cylinder 2. Got replaced and a week later you found another misfire on the same cylinder 2 again.

You did not think what was going on. The injector was just replaced and how come it went faulty again? Presumably you did not take that injector out on cylinder 2 to check the condition. You simply fitted two more injectors on cylinder 1 and 3.

This symptom just happened to me as well! I replaced one injector on cylinder 6 two months back and engine light lit on yesterday. The third time I turned then engine on, engine light was off. Just read the fault code and it says cylinder 6 misfired again. Exactly like your symptom.

So, I would just replace injectors on cylinder 5 and 4 then. There is no need to take out injector on cylinder 6 I suppose. Any advice?

It can be concluded here then that with 6 pots engines, replacing 1 or 2 injectors are not enough. 3 injectors must be replaced on one bank. Otherwise, the above symptom would occur.
 

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Yes I would say it’s prety much definite that at least all 3 injectors on the same bank should be replaced.

I had two faulty injectors which unfortunately were in different banks hence changing all 6. Happy to report that that was 6 months ago and I’ve done 5k miles since then with no issues.
 

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Discussion Starter #17
I must say that it is an interesting findings Mahoone. You found a misfire on cylinder 2. Got replaced and a week later you found another misfire on the same cylinder 2 again.

You did not think what was going on. The injector was just replaced and how come it went faulty again? Presumably you did not take that injector out on cylinder 2 to check the condition. You simply fitted two more injectors on cylinder 1 and 3.

This symptom just happened to me as well! I replaced one injector on cylinder 6 two months back and engine light lit on yesterday. The third time I turned then engine on, engine light was off. Just read the fault code and it says cylinder 6 misfired again. Exactly like your symptom.

So, I would just replace injectors on cylinder 5 and 4 then. There is no need to take out injector on cylinder 6 I suppose. Any advice?

It can be concluded here then that with 6 pots engines, replacing 1 or 2 injectors are not enough. 3 injectors must be replaced on one bank. Otherwise, the above symptom would occur.
No, I did not take the injector on cylinder 2 out because I knew if I just replaced remaining 2 in the same bank that will sort the issue.

Basically you can't mix index 11 injectors with lower indexes e.g.: 7, 8 or 9 in the same bank.
Here's why:

"IMPORTANT:
Injectors with index 11 and higher have a different calibration and construction than injectors with index 10 and lower.
Due to this difference, the injectors with index 11 and higher and injectors with index 10 and lower cannot be mixed
on the same engine bank (i.e., cylinders 1*3 or 4*6)."

"The DME assumes each injector in a bank operate the same and thus applies the same fuel trims and adaptation values to all 3 injectors on each bank. If one of them is operating differently, it will skew these values and cause all 3 cylinders to run poorly: 1 too lean and 2 too rich, or vice versa."

Looks like we both mixed the injectors and it didn't work.
 

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I'm glad I found this post, as I have the same issue but cylinder 3 for me. Only had the car 1 month so I am also in the same annoying trap with the warranty only covering 1x injector at a time. I have already had plugs, coils and 1x injector fitted.
I was thinking about fault finding oil leaks and fuel leaks but it more than likely needs 2x more injectors for the first bank to resolve the issue.
Is it possible to check the index number while the injectors are fitted? Otherwise I can remove. I had 6x new injectors in 2012 under a main dealer recall, with 2x full sets of coils done at the same time.
I also thought the fuel smell might be due to reusing old fuel line seals? Do they need replacing if buying second hand injectors?
 

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It’s index 11 injectors you need. The number is printed on the top of the injector so maybe visible without removing? I’m not sure though. The ones fitted in 2012 won’t be index 11. My car was November 2011 and injectors failed at 50k miles.

It seems very common that these issues occur soon after buying the car. The previous owner saw it coming and got rid, unfortunately leaving it down to the new owner to deal with.
 

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Discussion Starter #20
I'm glad I found this post, as I have the same issue but cylinder 3 for me. Only had the car 1 month so I am also in the same annoying trap with the warranty only covering 1x injector at a time. I have already had plugs, coils and 1x injector fitted.
I was thinking about fault finding oil leaks and fuel leaks but it more than likely needs 2x more injectors for the first bank to resolve the issue.
Is it possible to check the index number while the injectors are fitted? Otherwise I can remove. I had 6x new injectors in 2012 under a main dealer recall, with 2x full sets of coils done at the same time.
I also thought the fuel smell might be due to reusing old fuel line seals? Do they need replacing if buying second hand injectors?
Fuel smell in my car was due to me leaving old injectors in the boot and forgetting about it. All good now.

You can just about to see Index numbers on your injectors without removing them. Especially on first cylinders. You do need to take the plastic engine cover off.

I don't think there are seals on fuel lines so nothing to replace. You might be referring to 'o-ring' which sits at the bottom of the injector and needs to be replaced if buying second hand injectors. Same as de-coupling element.

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