Occasional white smoke with rough cold idle

[Tonyfeb14]

My 4.4 2003 X5, 151k miles has occasionally puffed billows of white exhaust, then cleared up. This happened to my wife twice and caused some emergency calls to me to come and get her.

When I got there, the car started, the smoke cleared and it ran fine. She was scared by all the white smoke and thought it would blow up.

Also, I have noticed in colder temps, just starting, the idle is very erratic until the engine warms up. In fact, it hardly runs, surges at idle and needs a lot of throttle correction until it warms up. Anything below around 60 deg is a problem so something is wrong with the enrichment circuit. I would think that points to the ECM.

On the smoke problem, it threw error codes for multiple cylinder misfires, and a load of other downstream catalytic converter problems, then clears up. I thought maybe head gasket or coolant leak would cause white smoke, but the problem clears up and all seems normal. I thought leaky fuel injector, but I figure that is likely one cylinder misfire, not multi cylinder misfires. I was ready to replace the injectors. I have also seen smoke now on startup when it sits overnight, but it clears quickly.

I started to think in might be an ECM problem since cold idle and sporadic smoke could be a fuel injection problem affecting multiple cylinders.

Out of curiosity I made the mistake of trying to clear all the adaptions in the ECM with my scan tool (because the tool would let me do that) and that just about did me in. It stalled, I got engine malfunction errors on the dash, and it hardly ran at all, lost the throttle response all together, lots of smoke, surging idle. I thought next stop was call a tow truck. Finally, after trying that again and shutting down and restarting, at least it is running again and I have throttle response. But the cold idle is still horrible, now maybe worse, until it warms up. And its not really that great when operating temperature, but a least idling around 750 rpm with a slight drift up and down.

Any ideas? I am leaning towards and ECM problem, and thinking of sending it out to have it tested and repaired. Buying a used 17 year old ECM on Ebay doesnt sound very attractive. There is a place that advertises for $200 they can fix an ECM.

But before going that path, thought to check on the forum for any ideas on what else to check. Always good ideas on this forum so asking to share some wisdom about this beast before I go much further on the ECM.

[tartilla]

I had a 1989 Camaro 305 small block, with the Tuned Port Injection, FI.

The ECM had an issue where it essentially turned on all the injectors. A very odd failure. I got about 1/4 the mileage, and the engine would 'hunt' at idle and lope. An incredible amount of amount of gas going through.

At no point did I have any white smoke.

White smoke typically from lots of oil consumption, or in some cases, coolant consumption, that is more white steam.

[80stech]

I think the V8s are notorious for valve stem seals so I'm guessing by "white" smoke you mean not black. Clearing adaptations is a good thing but NOT with the engine running. AFAIK, very unlikely that the problem is the DME/ECM so I wouldn't start with that.

[Purplefade]

80stech is likely on to it, the V8s are notorious for failing VSS, one test would be to start it and let it idle for an extended period of time, something like 10 minutes, like you were waiting in the driveway for tour kid to put on and tie their shoes (mine are slow as molasses ) and then give the gas pedal a good poke. Not the end all be all test by any means, but if you get a huge plume of white smoke, it will tell your a lot.

You’ll have guys argue that failing CCV valves can cause this as well, they’re pretty easy to access and a simple check. Pop the CCV caps off and check the orange “gasket” for rips, if they are ripped, replace those first, but I doubt it solves yours problem permanently. (Unfortunately)


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[crystalworks]

^ agreed with the above. Likely valve cover gaskets, valve stem seals, maybe other vacuum leak.

What codes is it throwing? Not "P" codes, but BMW specific dtc's?

[ValkyrE53]

I’m having similar issues, very rough idle on cold startup.
I first noticed the issue after flying cross country to pickup a X5 I bought, being stopped at long red light for the first time, and as I accelerated blue / white smoke out the exhaust. The smoke would only be noticeable when starting from a stop, as the oil would leak then burn on acceleration.
Reading up on this issue I found bad seals would cause that rough idle, especially on cold startup.

From good feedback here on the forum, for my issue it sounded much like worn valve stem seals, which for a DIY mechanic I’d have the engine opened up for a month, and I’m not prepared for such a job . . . not having that kind of free time, plus specialty tools (kits run $800+) which I’d need to find much cheaper on a small budget.

I did check & replace the (easy to access) PCV’s Crankcase Vent Valves . . . passenger side rubber had hairline cracks, but very little carbon buildup. Replaced that side with Bosch (oe) found on eBay @ $25.
The drivers side still looked ok, but I had found a Febi on eBay @ $16, and the curiosity of me always wants to see how an aftermarket holds up -vs- an OE brand.

Since I just bought this X5, I decided to take it to the BMW Stealership for State Inspection . . . plus see what kind of other troubles I purchased.

They advised the blue smoke is likely the Valve Stem Seals, but I could still pass Emissions, which it did. They thankfully advised I could still drive it no problem, but just maintain the oil level. Then the quotes crushed me, $7k to lower the engine from below, clean out the carbon and replace the gaskets and valve stems! $5k to open the engine from above and just replace those valve stem seals.

I explained I was concerned about dumping that much into such an old vehicle which I knew little about it’s history, care by previous owners, etc.
They then suggested a Pressure Test (they would need a whole day to perform) to see if it’s just those seals, or if other issue areas are present.
I didn’t schedule that yet, hesitant as I’m concerned that test might speed up the failure of other seals, or blow out the valve stem seals even more, leading to an insane oil burn rate.

I’d suggest doing the PCV’s, if the smoke still persists, decide for yourself based on how long you’ld like to keep the X5 if the valve stem seal replacement is worth it, because if that’s what it is, it’s not terrible to continue to drive it, just so long as you check the oil level weekly, and carry a funnel and some cheap fully synthetic oil with you at all times, just incase.

I typically swear by Mobile1 0w-40 (one of the last true synthetics) for my bmw’s, but when topping off a engine that’s leaking / burning oil I’m using this Walmart brand as it’s insanely affordable $31 for 12 quarts . . .

https://www.walmart.com/ip/Super-Tec...arts/937402631



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[Tonyfeb14]

Thanks guys. I will check out seals first. I have been using Mobil 1 0-40W for the past 100,000 miles and the inside of the engine is clean as a whistle. I also had changed valve cover gaskets when I did the valley pan last year. But if VSS are the problem, I MSU just drive it for a while before the next ride...maybe electric ��

[ValkyrE53]

Originally Posted by Tonyfeb14

Thanks guys. I will check out seals first. I have been using Mobil 1 0-40W for the past 100,000 miles and the inside of the engine is clean as a whistle. I also had changed valve cover gaskets when I did the valley pan last year. But if VSS are the problem, I MSU just drive it for a while before the next ride...maybe electric ��

Yeah, If I have to add 1 quart of cheap oil a month, I’ll deal with that until I decide next spring on either selling it or overhauling the engine myself.
Leaning towards selling, as I’ll continue looking for a 4.8is with 2-tone interior.

Speaking of Electric, just placed my reservation on a VW ID.4 electric RWD suv.
Test drive a Model 3 RWD last month, loved the acceleration but struggled to power slide it, so hope VW didn’t add any of that traction control garbage, or at least gives the option to disengage it, like bmw had.

[stiubhartach]

White smoke is usually the CCV system blowing oil into the intake manifold. Sometimes it’s the valve stem seals, but that’s expensive so should be looked at last.

Here’s a write up on fixing my problem.

https://xoutpost.com/bmw-sav-forums/...lem-fixed.html

[johnnyzcar]

I have been dealing with these issues for about 1 year now. Started with cold rough idle and sometimes white smoke on startup. I also had the alternator bracket leak that you will have if not already. I have replaced cams and eccentric shafts immediate levers to spark plugs to DME and coils. Used parts not new, new would cost 2 3 times what the car is worth.

The valve stem seals go bad in these motors, all of them, meaning v8s.
The job to replace them takes a while and I could prob do it in a weekend in my garage. I have had the heads apart in mine probably 5 times now and I am pretty proficient in it, not to my choice though.

It's cheaper to buy a replacement motor however if you try to get one for our age car it will have the same issues. I looked into getting the newer 4.8 which is doable but there could be some issues with harness and if the motor is out of a car you need to swap the oil pump and oil pan etc.

I removed the cats on mine and tricked to post O2 sensors with a defouler. It runs better but still has same issues.

I am at the point of cutting my losses and selling the car as I don't like throwing money away. I have learned a lot though.

Members feel free to chime in but sometimes the turth hurts. I see these V8s in BMW cars all the time and guess what, they are all smoking white smoke out of the tail pipes. It's a shame that an old chevy would last longer than what is supposed to be an upscale, highly technical engineered machine. Then again the did loose the war for this very reason.