Overnight Cold Start Rough Idle N62 4.8iS

[crystalworks]

The o2 sensors shouldn't cause cold start misfires now that I am thinking about it. Vehicle should be in open loop and not using their data. Don't know why I didn't think of that before.

Have you (could you) do any data logging of a cold start where the rough start was present?

[mr_robot]

I can see live data with INPA but can you record with it as well?

[mr_robot]

So frustrated, hate these inconsistent, intermittent problems so hard to properly diagnose.

So this morning, it did it again, started up rough from the start. CEL flashing until it normalized then drove off.

But today, 2 min into driving coming to a stop light, it started flashing for like a sec and went away again. Today was pretty cold, car was covered in frost all over.

I seriously don't think it's my levers now. Because according to the SIB, I should experience rough idle AFTER 60 sec of cold start when it's switching from 6mm to .3/.8mm lift. Mine just starts rough from the start (again sometimes, sometime it does idle normal and goes into rough after 60 sec or so or sometimes doesn't do it at all!)

Does anyone know if when DME adaptation is reset so does the Valvetronic adaptation?

Been reading about E46, E39, E60, E70 guys talking about VVT adaptation reset? Does it apply to E53 N62 or is it all controlled by the DME?

I do see a part number for Valvetronic Module that is separate from the DME.

[X5only]

Originally Posted by mr_robot

As far as I know the N62 in the 4.8is doesn't have a secondary air pump. Just the vacuum pump on the right side of the timing cover.

Or am I not following you?


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Correct, the X5 N62 doesn't have those emission air pumps. They're on 5 and 7 series N62 engines, the air pipes and pumps located under the intake manifold.

I would have thought the issue you're facing is the known intermediate levers problem that requires replacement with updated version? I'm just glad I verified mine are the updated version while doing the valve stem seals.

The other thing to note...was this issue there BEFORE the valve stem seals were replaced? I ask because during valve stem seals replacement, if the rocker arms are mixed up while installing them back (they have different tolerances for each valve stem), or if the spring keepers are installed up-side down, you could have intermittent misfires - exactly what you're describing. I did the valve stem seals myself and I rechecked and rechecked and rechecked yet again that I didn't make those mistakes. Just a thought....

[mr_robot]

This was present before the VSS was done. I did the VSS sooner than anticipated in hopes that any leaks would be addressed, solving this separate issue but it has not gotten worse or better after the VSS, but doesn't smoke anymore though =)

[dadysev]

Coldest day today in Toronto and just had this same issue. went to start, it was rough, ran then shut off.
After i got it started and revved it up a bit the idle was hunting from about 500 to 900 for a bit also.
I didn't check for any black smoke on first start for extra fuel from leaky injectors but i may start to check fuel pressure and leak test the injectors this week. i will let you know what i find.
Also only noticed this on the really cold days. No issues last week.
Also no faults or CEL flashes.

[Emory39]

It happened to me the other day for the first time since I have the X.
CEL flashing and all. I shut it off a restart and held it, at 900RPM for 15 seconds it idle just fine. Codes where the random misfire and what not. I am going to rule out what I have replaced; spark plug,s fuel pump, fuel filter, and CCV. The VVT should not be my problem as my ECM has a tune so lift specification are different ( I will read live data next weekend when I park the X outside again) the only thing That I know is OE, is the Ignition coils.

[mr_robot]

Mine is so random. Like this morning, 9*F and started up without a glitch no flashing CEL.


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[dadysev]

Just fired up the heater in my garage and started diagnosing. Fuel pump recall was done last week, so new fuel pump. Solid 50psi while running.
Did the leak test and it holds about 42 psi over an hour, but at this point the engine was a lot warmer than last night!
I'm guessing my battery was a little weaker than normal, and/or the injectors could have leaked a little over night with these super cold temps, and i also didn't start the truck yesterday at all with close to the same temps as today.
I give up!!!

Also i don't think we have the IVN module in the E70's as i'm trying to diagnose a starting issue with another E70 but a 3.0 where the starter does one click for half a second.
I found the starter relay in the CAS module under the steering wheel with a burnt surface mount diode and a trace by the white starting relay on the board. if I jump the starter wire to the main power supply wire it starts.
This is another issue which i know is caused by bad ground from the body to the engine block.

[bcredliner]

Since the issue is associated with cold mornings, first startup and goes away after a minute or less it could be an open loop problem. When the engine is cold and first starts up it is using a pre programmed air/fuel mixture. It does gather a little info from MAF and water temp but primarily it is using the pre programmed formula. Since your problem goes away and engine operates normally it is not likely the thermostat. I would eliminate the MAF as the potential problem. It is not likely the programming has changed but could have.

Sometimes a vacuum leak seals itself when the engine starts to warm up. I note you have done a smoke test. Was test done on a cold morning prior to starting the engine?