E70 misfire on cylinder 1

[ard]

BMW has an issue when voltages get low and their 'intelligent battery management' software fails to provide enough voltage to certain modules. The old days of a solid '13.4V when running' are gone. BMW actually allows the voltage to drop to avoid putting a draw on the alternator and motor during cold start. Emissions I think. (This is the reason you hear about 'short drives' leading to battery issues.) But it can also cause sporadic issues with various modules. I dont think this is likely as yours is very repeatable.

You SHOULD get a CPS error when they fully fail. But we have come to learn that they can internally degrade and lead to shifted values/signals. The DME doesnt run a complete diagnostic on every aspect of the signal: it is there or it is not there. If it is there, but distorted, you get no CPS code but distorted cam timing. Can that manifest as a misfire? Dunno.

In the E39 S62 land we just recommend replacing all 4 CPS as maintenance. Period. Why mess with a sniper-shot diagnosis, when the prepondernace of evidence points to 'you will need to replace these eventually.'

I dont know the part numbers- look them up. If different part numbers then they are different.

[Markyboyslm]

Finally got DIS installed and did a check on the Vanos and intermediate levers tolerances. Both tested ok. It is spring now so outside temperature is warmer. I don't get many misfires anymore... maybe once every 2 weeks. I still notice the acceleration hesitation but it is less severe. Some days there is no hesitation at all and other days it is quite noticeable.

On the days with no misfires I do notice that the car idles higher when first started. Maybe 700-800rpm and then when it warms up it drops down to 500-600rpm. Is this a clue? Temp sensors? What causes the higher idle at startup?

In DIS I did notice that the battery looks like it was replaced with a mileage just before I purchased the car. Maybe someone was trying to fix the misfires before selling the car... Who knows?

[Mongojoe]

Yikes. Had the same fault this past weekend. As part of the N63 Customer Service Pkg, dealer is replacing all injectors, fuel pump, hoses, mass airflow sensor, and plugs. Fingers crossed.

Has your vehicle had this done? Even if it is out of warranty, might they cover it if it was never performed?

[Markyboyslm]

***NOT PROBLEM SOLVED!!!!*** 2007 BMW X5 4.8 N62 engine
keep reading below

Messing around with the DIS software I was able to read something that said "sporadic low voltage DME"
I first went to the battery to check and all connections and voltages looked fine.
I then went under the hood on the passenger side near the firewall and got down to where the DME is located. Poked around a bit to see if any water leaked into any components or looked for any faulty connections. It is a mess of wires in there!! I did unplug the 2 40amp fuses and looked at the 2 relays in the DME compartment. Couldn't find anything visually so I buttoned everything back up and went to start the car.
I thought I should check the codes before starting the car as I unplugged the DME fuse and figured I would get some kind of DME error code.
To my surprise I had "Misfire on Cylinder 1" !!! The car did not have that code when I parked it and I had not even started the car yet.

I then came to the conclusion that there was an electrical problem with the DME that was causing my misfire code.

I went back in to the DME compartment unplugged everything and cleaned the connections with electrical cleaner. I did re route some of the wires as they were overlapping quite a bit with some large gauge red 12v wires with some of the smaller gauge wires. Unplugged the fuses and sanded the ends to make sure they have good contact and are able to transfer 12v properly.

Car has been running amazing since. No misfires in 3 weeks.
My hope is that this info helps someone out there. It is such an easy thing to check and requires no money or tools for that matter.
+1 for ARD as he set me on the right track with the post above Thanks

[Bagherra]

New owner here....what is the DME?
Just starting getting a slight hesitation at idle. CEL illuminated, pulled code and its P303 Cylinder 3 misfire.

Prolly gonna move coil this weekend and see what happens...

[ard]

DME = Digital Motor Electronics

Engine Computer.

Google DME and BMW:

BMW Technology Guide : Digital Motor Electronics (DME)

[Markyboyslm]

After months and months of no misfires. Cold weather has returned along with the misfires.
Still only misfires on cylinder 1. Start the car it idles smooth, let it idle for 15-30 seconds, pull out of the driveway by the time I hit the end of the street and start to accelerate BOOM misfire and I can feel it running rough. Pull over shut the car off and turn it back on and it runs fine the rest of the day. The kids down the street at the bus stop must think I am weird stopping and starting every morning lol.
Took the car to a local shop and they did a smoke test which showed no leaks. They wanted to change coils and plugs which I declined. I have moved coils around and changed plugs already. They said maybe I need a software update and suggested I take it to the dealer to check out.
I may take it to the dealer. Just hope they don't tell me to change my coils like the other shop.

[bignasty27]

Did you find a solution to your issue?

[e70jane]

Originally Posted by Markyboyslm

After months and months of no misfires. Cold weather has returned along with the misfires.
Still only misfires on cylinder 1. Start the car it idles smooth, let it idle for 15-30 seconds, pull out of the driveway by the time I hit the end of the street and start to accelerate BOOM misfire and I can feel it running rough. Pull over shut the car off and turn it back on and it runs fine the rest of the day. The kids down the street at the bus stop must think I am weird stopping and starting every morning lol.
Took the car to a local shop and they did a smoke test which showed no leaks. They wanted to change coils and plugs which I declined. I have moved coils around and changed plugs already. They said maybe I need a software update and suggested I take it to the dealer to check out.
I may take it to the dealer. Just hope they don't tell me to change my coils like the other shop.

I know this is an old thread but I've been going through similar issues with my 07 4.8l but I don't get the cylinder misfire fault. I use Carly which gives me a bunch of CAN faults. I have the hesitation and cel also. When it first started, it was the cel and just a little bit of hesitation at the throttle. Once I clear the faults, the cel goes away and it drives normal again. However, after a good few miles of driving, the cel and hesitation returns. It's gotten worse overtime as now the Cel comes back at every other startup. I changed and tested a bunch of stuff, even thought it was a voltage issue at one point, nope. Got ripped off by the stealership by replacing the IBS and negative cable. Then I replaced the alternator myself, checked and cleaned the vanos, replaced the battery, still the same. Then I replaced the eccentric sensors, which were fine, but along the way I discovered a fallen rocker arm on bank 1. I was for sure that this was the problem but it wasn't! So this weekend, I'm going to check the crank sensor and replace the dme relays and hopefully this will solve the mystery. If it still doesn't solve the problem, I'm getting rid of the POS!!

[Baby Unicorn Taco]

Originally Posted by e70jane

I know this is an old thread but I've been going through similar issues with my 07 4.8l but I don't get the cylinder misfire fault. I use Carly which gives me a bunch of CAN faults. I have the hesitation and cel also. When it first started, it was the cel and just a little bit of hesitation at the throttle. Once I clear the faults, the cel goes away and it drives normal again. However, after a good few miles of driving, the cel and hesitation returns. It's gotten worse overtime as now the Cel comes back at every other startup. I changed and tested a bunch of stuff, even thought it was a voltage issue at one point, nope. Got ripped off by the stealership by replacing the IBS and negative cable. Then I replaced the alternator myself, checked and cleaned the vanos, replaced the battery, still the same. Then I replaced the eccentric sensors, which were fine, but along the way I discovered a fallen rocker arm on bank 1. I was for sure that this was the problem but it wasn't! So this weekend, I'm going to check the crank sensor and replace the dme relays and hopefully this will solve the mystery. If it still doesn't solve the problem, I'm getting rid of the POS!!

I don’t know if you have already changed the plugs but a bad/out of spec plug can cause this issue. A bad plug won’t always set off the CEL. I was able to use my scanner and look at fuel trims on each cylinder. I ended up replacing all my plugs but the cylinder that had the worst plug had a measurably different fuel trim. This was the cylinder causing the hesitation.


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