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BMW 645 E64 - Engine Misfire

1K views 9 replies 5 participants last post by  blackdaemon 
#1 ·
Hi all,

My 645 has been sat on the drive since lockdown. This week before driving for MOT, car sluggishly fires up but looking at the Live data on Carly app, I saw the voltage was dropping, generator not working and slowly the car went to limp mode. As the revs was dropping I tried to rev up. I Was trying to keep it alive but it died anyway.

long story short, the battery has now been charged up, generator working ok. Only, when I reverse, the car shakes a lot and surges. When on the motorway and I put my foot down, it surges a lot before revving up to desired speed.

I thought I’d use INPA to check for engine backfire but it look ok. I said ok because it doesn’t return any code for engine backfire. I did live running data on INPA looking at the analogue 1, 2 and 3 data.

I have some pictures attached and I’ll appreciate if someone with experience of INPA and backfires to help explain if the analogue readings are ok or I’ve f*ked sheet up by revving the engine when in limp mode.

The MOT guy says the car is in good shape which I love to believe but having used 3 of the 645’s I can sense when something ain’t right.

I’ll appreciate your opinion. See attached photos.

Thanks!

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#2 ·
There's nothing wrong there - all screens show good running conditions. So, it sounds more like a gearbox problem to me - try running INPA on that and see what you get.
 
#3 ·
Hi Tim,

Thanks for the reply. I checked the transmission and had 2 errors in memory but in German. I’ll try and translate what they are.

can you make anything out of the screenshots attached other than the error which I’ve now cleared? The engine was in idle so some data were no on or trending

Let’s know thanks

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#5 ·
Belt and braces and bearing in mind I know nothing of this particular cars handbrake characteristics, but I had the thought that if the car's been stood, presumably with hand brake on, and it now judders in reverse, I'd have a check of the handbrake to see if the pads or shoes haven't stuck on, or just not fully released.
 
#7 ·
just an update on my car. Still getting the old roughness and today while out at the Riverside, the MIL lamp comes one and it threw a fault code - 274E and 2742 on Carly diagnostics. The code description being misfire in Cylinder 1. Bimmerpost gives further descriptively (attached).

It cleared itself before I could.
Unfortunately I didn’t have my laptop with INPA in the car.

Got home, checked with INPA and the roughness is still there but no stored errors in memory. I put it in reverse and it shakes like crazy. I put A/C off and settles ok without roughness

Could it be the spark plugs for cyl.

many thoughts please look at the attached photos
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#8 ·
More likely to be the coil-over-plug unit, swap it with cylinder 2 and see if the error code follows the coil. Plug and coil removal here:


....and the Lambda sensor before the cat on the RHS (when viewed from behind) has failed and will need to be replaced
 
#10 ·
Make sure your battery is in top notch condition.
Sometimes the battery is so bad that charging it helps just intermittently and it needs replacement anyway.
It can cause all sorts of strange unrelated problems like it did on mine, when car demands voltage and the battery can't handle the peak:

  • Transmission errors on CCC, car going into limp mode. No transmission related errors in INPA
  • Rough shifting ocasionally, again no transmission errors in INPA
  • Sometimes loss of power, no reaction on gas pedal
  • Rough idle

All that resolved with brand new AGM battery, properly registered.
 
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