Overnight Cold Start Rough Idle N62 4.8iS

[crystalworks]

Gotcha. I'm kind of stumped then. Misfire codes by themselves don't really give you a ton to go on.

BTW I posted fitment pictures of that head unit in a thread I just started.

[mr_robot]

Just another update, I started the car this morning and perfect. No rough idle or flashing cel.

This was after sitting over 24hrs as I didn't drive it at all on Sunday and mornings are colder than ever now. Really stumped on this.

The only change is that I put a solar battery tender via the rear cargo 12v outlet since Saturday morning.

I put a solar charger because of "possible" weak battery issue. But have no other symptoms of a bad battery.

Will report back if this is due to a weak battery.

So is it possible that a failing battery could cause this? Doesn't the alternator take over as soon as you start the car?


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[crystalworks]

^Could be coincidence. Usually once the car is started, provided the alternator is providing good voltage, and the battery isn't TOTALLY shot... it should idle just fine.

I was going to ask if your o2 sensors had ever been changed.

[mr_robot]

As far I know it has not been changed. But from my experience o2 sensors either work or they don't. And would definitely throw a fault code either via obd or bmw scanner as soon as possible.


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[crystalworks]

^Normally I would say the same. I just replaced mine @ 118,000 miles with no CEL. First startup was fast and smooth. More so than "normal." I've also read here reports of others getting better gas mileage after replacing the front o2 sensors. I had them here and was under the vehicle so figured I would do them. Was surprised at how fast and smooth the first start was.

That's just one start so far though... and is just anecdotal. Nothing concrete yet that the sensors will provide any better service than the ones I removed.

[mr_robot]

Yes I'm sure a new clean o2 will perform better than a used one. I was thinking of changing mine too ever since doing the vss job. I don't know how long it's been going on because the previous owner swore it never smoked. But judging by how little it smoked I'll give him the benefit of the doubt that he probably didn't know.

So I have been doing a lot of the "Italian Tune-Up" lately or any chance I ever get since the VSS was performed LOL


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[crystalworks]

Gotta blow the carbon off those valves right!

[X5only]

Originally Posted by crystalworks

^Normally I would say the same. I just replaced mine @ 118,000 miles with no CEL. First startup was fast and smooth. More so than "normal." I've also read here reports of others getting better gas mileage after replacing the front o2 sensors. I had them here and was under the vehicle so figured I would do them. Was surprised at how fast and smooth the first start was.

That's just one start so far though... and is just anecdotal. Nothing concrete yet that the sensors will provide any better service than the ones I removed.

What O2 sensors did you install - OEM? Mine are original and at 120k miles, I think I better change them now.

[crystalworks]

I used Bosch sensors from fcp so that if I ever have to do them again... They're "free.".

[jsoto]

mr_r

I can see how if one was leaving the car at the airport and throwing the solar charger on it just because. Personally, I can't see how much juice it could be putting back into the lead acid- in the mah range. If it's a short tripper daily driver, even in this current chassis or ones with [email protected]% SOC, I'd err on just a 120V charger as any lead acid is most happiest when @ full SOC

btw, I might have missed it. did you get around to charging and then doing a load test post charge.