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135i N55 misfire

6K views 26 replies 6 participants last post by  Jemaine 
#1 ·
I am experiencing misfire on my car. I had the garage change the plugs with the new original BMW. While monitoring the data through MHD I get random misfire on all cylinders and it occurs randomly. Sometimes all cylinders misfire sometime just couple. There are no codes apart from 387F and some shadow codes. It came on after I changed 3 new coil packs. The car misfires more frequently stationary at 1k rpm.

I have also noticed that my fuel rail pressure is jumpy at idle approximately 20psi (704.5-724psi). Not sure if this is normal or should it remain constant.

If anyone might have some input it will be much appreciated.



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#10 ·
Unfortunately I keep getting random misfires in all 6 cylinders and there is no patern in recurrence. Initially my misfiring was related to the wrong plugs that mechanic installed for me (N54 plugs). I have changed all 6 plugs to Bosch ZR5TPP33S, gap untouched, all was good and then again there were couple of misfires in cylinder 5. I removed all the plugs and reduced the gap to 0.022 after putting everything back I get misfires across all 6 randomly. There are no codes, only when monitoring through MHD live data. I don't know what can be the cause. Can someone please guide me where else to look? It's becoming very frustrating.

Many thanks,
 
#11 ·
Have you done a full log with all the nannies off to see if you get misfires then?

I get random misfires when just logging live but when I do a full log with dtc off and full throttle no misfires
 
#13 ·
steveo08 said:
Have you done a full log with all the nannies off to see if you get misfires then?

I get random misfires when just logging live but when I do a full log with dtc off and full throttle no misfires
Thank you for the reply, after changing to the right plugs I haven't done proper log with dtc off, certainly will need to. The misfiring is inconsistent it can happen at idle, normal driving, or full throttle,I cannot undestand what could be the trigger. As there is no pattern (to my believe) in misfire it might not happen during the log. Can you please kindly tell me more about your logging live misfires do you get occasional random misfiring across all 6 cylinders? Is your fuel pressure constant at idle or a bit lumpy like mine?

Thanks
 
#16 ·
Zutm710 said:
steveo08 said:
Have you done a full log with all the nannies off to see if you get misfires then?

I get random misfires when just logging live but when I do a full log with dtc off and full throttle no misfires
Thank you for the reply, after changing to the right plugs I haven't done proper log with dtc off, certainly will need to. The misfiring is inconsistent it can happen at idle, normal driving, or full throttle,I cannot undestand what could be the trigger. As there is no pattern (to my believe) in misfire it might not happen during the log. Can you please kindly tell me more about your logging live misfires do you get occasional random misfiring across all 6 cylinders? Is your fuel pressure constant at idle or a bit lumpy like mine?

Thanks
Mine were across all cylinders no more than -3 and they happened when wot. I thought it was my coils but I get no misfires with dtc off so put it down to traction control interference.
 
#17 ·
Thanks, It looks like I might have something else. Today, I turned off the DTC and drove normally and unfortunately misfire occurred in multiple cylinders. What I also find strange is why there is no fault being registered? Could it be issue / glitch with MHD monitoring?
 
#19 ·
Zutm710 said:
Thanks, It looks like I might have something else. Today, I turned off the DTC and drove normally and unfortunately misfire occurred in multiple cylinders. What I also find strange is why there is no fault being registered? Could it be issue / glitch with MHD monitoring?
Does MHD block or clear some engine codes in a similar way to the JB4?
 
#20 ·
Toed64 said:
Zutm710 said:
Thanks, It looks like I might have something else. Today, I turned off the DTC and drove normally and unfortunately misfire occurred in multiple cylinders. What I also find strange is why there is no fault being registered? Could it be issue / glitch with MHD monitoring?
Does MHD block or clear some engine codes in a similar way to the JB4?
That is interesting question, I have never used JB4. As fas as I know MHD does not block or clear any codes. If there are any errors you can scan for it and it gives you an option to clear it.
 
#21 ·
Hi @Zutm710,

I am Jemaine,

I'm having this exact issue with my 135i N55 and I've tried just about everything.

- New plugs and coils.
- Bench tested all injectors
- Tested O2 and MAF sensors

I'm still getting misfires on random cylinders under load.

I'm hoping that you've gotten to the bottom of your issue and that you can advise me.

Thanks.
 
#25 ·
Thanks for the response Artur.

My car is 6mt.

We've tried running various diagnostic tools including BMW ista without any conclusive results.

Unfortunately my DME is locked and it is a bit difficult for me to spend more to get mhd working without knowing if it's even going to help the situation.

In terms of the new spark plug gap - I was informed by BMW that they come pre- gapped so I did not check this - though by inspection I don't notice any deviation in the gap between the plugs.
 
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