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-   -   Rough Start, Then Fine - lean engine codes (http://www.bimmerfest.com/forums/showthread.php?t=650555)

thompsonmd 10-08-2012 07:57 AM

Rough Start, Then Fine - lean engine codes
 
Guys, thanks in advance. I always come back when something goes wrong and somebody points me in the right direction right away.

2006 BMW X3 3.0, 85k, fresh off warranty (of course).

Upon starting the engine runs rough for a few seconds, then it is fine. By rough, I mean the RPM fluctuates. As soon as the gas is applied or a few seconds pass, it operates completely fine. Acceleration, MPG, oil consumption, all fine.

It only does this if it has been sitting for a few hours. Always does this overnight, whether parked in the heat or cold, or humid or dry.

Occasionally, anywhere from a few hours to a month, it will throw the lean codes for both banks, P0171 and P0174. Has done this for about 4 months. Never any other codes.

I have replaced the filthy air filter, cleaned the MAF, and even replaced the plugs. I have superficially inspected the air intake as far as I can without removing anything except the air box, or getting under the engine. The rubber all looks fresh and I can't see any cracks, or hear any whistles or leaks when it is running.

I stopped by an indy shop for brakes and told him the issues. He suggested that perhaps a fuel injector slowly leaks when the car is off, building up fuel in the cylinder. Then it is cleared out after a few revolutions.

Any thoughts?

X3-terrestrial 10-08-2012 09:44 AM

Hi There!
I replaced my fuel filter over the weekend and through all my searches for information I ran into this on another forum, and I quote: " Remember to re install fuses and reset fault codes if you have had a lean mixture bank error.

To dispel myths, it is entirely possible for a fuel filter to cause drastic lean conditions and fuel pump noise. It only takes one really dirty batch of fuel, plus an old contaminated fuel filter to cause this issue. Clogged filters will throw up lean codes usually.. If their is fuel pump whine/groan, sluggish performance, feels like theirs hesitations and CEL on try this first.. You should change fuel filter with the pump if it is this bad anyway."

I had some episodes of running rough and even stalling, and before blaming a tired fuel pump, I did plugs and fuel filter to eliminate them from the equation. No codes in my case though.
http://www.bimmerfest.com/forums/sho...d.php?t=648694

mlukas161 10-08-2012 10:07 AM

Quote:

Originally Posted by thompsonmd (Post 7120633)
Guys, thanks in advance. I always come back when something goes wrong and somebody points me in the right direction right away.

2006 BMW X3 3.0, 85k, fresh off warranty (of course).

Upon starting the engine runs rough for a few seconds, then it is fine. By rough, I mean the RPM fluctuates. As soon as the gas is applied or a few seconds pass, it operates completely fine. Acceleration, MPG, oil consumption, all fine.

It only does this if it has been sitting for a few hours. Always does this overnight, whether parked in the heat or cold, or humid or dry.

Occasionally, anywhere from a few hours to a month, it will throw the lean codes for both banks, P0171 and P0174. Has done this for about 4 months. Never any other codes.

I have replaced the filthy air filter, cleaned the MAF, and even replaced the plugs. I have superficially inspected the air intake as far as I can without removing anything except the air box, or getting under the engine. The rubber all looks fresh and I can't see any cracks, or hear any whistles or leaks when it is running.

I stopped by an indy shop for brakes and told him the issues. He suggested that perhaps a fuel injector slowly leaks when the car is off, building up fuel in the cylinder. Then it is cleared out after a few revolutions.

Any thoughts?

Pull the DISA and check for a broken flap with no resistance. I had this problem last year with our 2004 X3. Similar symptoms.

jdauria 10-08-2012 10:52 AM

check lower intake boot, could have a tear. Easy fix

thompsonmd 10-08-2012 11:47 AM

Thanks guys, I'll take off the DISA and lower intake boot, and more closely inspect for bad valves and cracks.

jdauria 10-08-2012 01:37 PM

Quote:

Originally Posted by thompsonmd (Post 7121032)
Thanks guys, I'll take off the DISA and lower intake boot, and more closely inspect for bad valves and cracks.

You don't have to take out the lower intake boot, you can just reach in and feel if there is a hole. Here is a picture of my lower intake boot when I was throwing codes on my e46, yikes:
http://i915.photobucket.com/albums/a...00519-1031.jpg

Supercourse 10-08-2012 01:42 PM

Quote:

Originally Posted by thompsonmd (Post 7120633)
.... Upon starting the engine runs rough for a few seconds, then it is fine.

...... It only does this if it has been sitting for a few hours.

.... codes for both banks, P0171 and P0174.

.... filthy air filter,

.... He suggested that perhaps a fuel injector slowly leaks when the car is off, building up fuel in the cylinder.

The indy guy's suggestion sounds very plausible except it doesn't explain the lean codes.

A cracked intake boot, or problems with DISA, fuel filter, or fuel pump should present symptoms other than just at first start up.

Was the air filter element very dirty because there was an oil film on it?
Did much dirt come off the MAF when sprayed?
Did the original plugs look as expected after 85K miles?

Could be early waring signs of a clogged crankcase vent valve/oil separator:
- bit of oil on plugs needs to get burned off after a cold start but not enough to affect warm start
- P0171 and P0174 codes consistent with CVV/CCV issues

Even though your oil consumption is not noticeable, might be worth ruling this out by the usual simple tests.
Such as checking underside of oil filler cap for goop, and checking for vacuum when cap is removed with engine running.

thompsonmd 10-09-2012 06:50 AM

I am going to check out everything that was mentioned. I'll give any intake rubber a more complete inspection, and check the vacuum and goop on the oil cap.

I had the CCV replaced on my 2002 330i after a DISASTER...took the car on a trip last winter where it sat for two days with a low of -20F...when it came time to start I guess the valve was gooped shut and sucked oil into the engine, white smoke everywhere, and a lengthy tow back home. Lesson for all...if you see white goop under the oil cap, replace the CCV. It didn't help that my thermostat was malfuctioning so the car never fully heated up on the way there.

thompsonmd 10-09-2012 06:51 AM

And thanks much for the pic. I don't know the names of a lot of that intake stuff...including the DISA.

883sportster 10-09-2012 07:40 AM

So would it be advised for people living in colder climates to swap out the CCV with a climate version? Just wondering since I just got our 2006 x3 and will be leaving it outside this winter (south east PA-Harrisburg area). Not to mention when I visit family in north western PA around Christmas time it can get pretty cold at night.

X3-terrestrial 10-09-2012 08:35 AM

Quote:

Originally Posted by 883sportster (Post 7122562)
So would it be advised for people living in colder climates to swap out the CCV with a climate version? Just wondering since I just got our 2006 x3 and will be leaving it outside this winter (south east PA-Harrisburg area). Not to mention when I visit family in north western PA around Christmas time it can get pretty cold at night.

Some of them already have the "cold climate" CVV version. You would have to actually look at it to be able to tell.
It could be advised to swap to the cold climate version, if you don't mind to pay around USD $800.00 of your hard earned money to have it done. Or invest at least 8 hrs of your time to do it yourself. (Very involved job)

thompsonmd 10-09-2012 01:34 PM

My DISASTER was a long time coming, it was with a 2002 330 (but same engine, I think). And it had been building up the white/tan goop under the cap and consuming oil for a year or more. Then, the heat gauge would never quite reach the 12 o'clock position, it would hover around 11. I asked the Indy guy, he said perhaps it was a faulty temp gauge. He couldn't believe that it was a faulty thermostat. Anyway, combine that with driving up to northern Wisconsin during a snowstorm, and letting it sit for the weekend in -20F, which was so cold that they canceled part of the cross country ski race I was going to race in. That was a recipe for disaster that resulted in CCV replacement, thermostat replacement and of course the awful tow back home. I didn't want to wait around up north trying to find a shop that could get it done reasonably quickly.

jdauria 10-09-2012 02:14 PM

Your entire cooling system may need replacement soon. BMW is notorious for this problem around 100k miles, I did a cooling system overhaul on my e46 way before 100k and haven't looked back. I think it was roughly ~$400 from ECS Tuning for all the parts.

thompsonmd 10-13-2012 12:10 PM

So, I inspected the intake boot again, looks totally fine on every part I can see. I also checked the vacuum on the oil cap, it was strong. I was impressed. I didn't know there would be any suction there.

I decided to start over, and take a look at the MAF again. That is the logical place to start, and when this first happened the first thing I did was get out the MAF cleaner and follow the instructions. Today, looking at the MAF, I saw that there was some rust, or corrosion on the actual sensor tip. I took off the cover and gave it a real cleaning. I used the spray, but also rubbed it with a cloth and a small knife to get the residue off. Yes, we are told how delicate this thing is, but I figure that with that residue I might buy a new one anyway.

But I cleaned it up, we'll see if that fixes everything.

Supercourse 10-13-2012 01:47 PM

Quote:

Originally Posted by thompsonmd (Post 7131901)
I also checked the vacuum on the oil cap, it was strong. I was impressed. I didn't know there would be any suction there.

I'm not an expert on this oil filler cap removal test, so someone else can chime in, but as I understand it:

1 of 3 things can be observed.

1. air blowing out which indicates a failed CCV

2. nominal suction which indicates everything working normally

3. strong suction which indicates a blockage somewhere in the CCV system but the valve itself still working

In addition, the revs should drop a bit as you are introducing a vacuum leak, and if it stumbles it should recover itself.

If you already have a vacuum leak, I suppose that either any further drop in revs might not be noticeable, or it will to the extent that it stalls.

fivepointnine 10-14-2012 08:57 PM

strong suction and car stumbling whith oil cap removed indicates a failing CCV.....I went thorough this issue last year. Fluctuating idle at startup and then it smoothes out. Lean codes on both banks. About $500 later at an indy shop and it was solved.

thompsonmd 10-22-2012 01:14 PM

For anyone that is following, ugh. My engine was fine for a few days, then the old damn light shot back on. So perhaps my rough cleaning of the MAF did not do the trick, maybe it's blown, maybe it's defective. But I can't get over the fact that the symptoms point to a bad intake issue, that my air filter was filthy, that my MAF was dirty...so I went ahead and ordered a brand new one for ~$250 from oembimmerparts.com. If this fails, I'll pay the Indy guy for a CCV.

In other news, climate control issues, which I'll start another thread on. Actually made me check the kbb.com value of this beast to see what I could get on a trade in. Nothing is better than spending a few hours and fixing a problem yourself, but nothing is more frustrating than spending a few hours and being back where you started. Updates to come.

AzNMpower32 04-14-2013 06:42 AM

For the past week or so, a similar situation has been cropping up in my X3.

When starting the car, it's a little rough and the revs fluctuate a bit for the first few sections, and then settles. Occasionally (usually after sitting an hour or so), some white smoke will come out from the tailpipe.

The vehicle itself drives fine with no detriment to fuel consumption or oil consumption. Engine coolant temperatures are normal. When it first starting occurring, I went to Autozone and no codes were found, and no warning lights have illuminated. I just did an oil change last weekend (after this started happening); the oil filler cap is clean- no unusual colours or gunk.

Ideas?

thompsonmd 04-15-2013 06:38 AM

Thanks for bringing this topic back up. After trying all sorts of mumbo jumbo, the simple answer for me ended up being to replace the intake boot. Yes, it's a bit of a pain in the ass, but it's only a $36 part and easy to tell once removed if it was the problem.

I cleaned the MAF (did nothing); replaced the MAF, cleaned and replaced the air filter (filthy) and even changed out the plugs.

The engine code would disappear for a while, once for even about 6 months, but the rough start never changed.

Two weeks ago I bit the bullet, followed a DIY and replaced the intake boot and inspected the DISA. DISA was filled with carbon, but seemed to work fine. Intake boot had a tear in the smallest, impossible-to-see-unless-removed hose. Two hours total.

Now I'm finally running legit.

jdauria 04-16-2013 04:37 AM

Quote:

Originally Posted by thompsonmd (Post 7519240)
Thanks for bringing this topic back up. After trying all sorts of mumbo jumbo, the simple answer for me ended up being to replace the intake boot. Yes, it's a bit of a pain in the ass, but it's only a $36 part and easy to tell once removed if it was the problem.

I cleaned the MAF (did nothing); replaced the MAF, cleaned and replaced the air filter (filthy) and even changed out the plugs.

The engine code would disappear for a while, once for even about 6 months, but the rough start never changed.

Two weeks ago I bit the bullet, followed a DIY and replaced the intake boot and inspected the DISA. DISA was filled with carbon, but seemed to work fine. Intake boot had a tear in the smallest, impossible-to-see-unless-removed hose. Two hours total.

Now I'm finally running legit.

I win. Congrats on getting her back in shape. Keep motoring :thumbup:

AzNMpower32 04-18-2013 07:21 PM

The X3 finally tossed the lean engine codes today, after over a week of intermittent symptoms. I guess replacing the intake boot would be the best first step, since I can't readily tell if its the cause but is the cheapest potential solution.

Update: Got a diagnosis today from an indy shop. Sadly they determined the cause to be the CVV so that's $930 on top of the $1400 I spent just a month ago for repair/maintenance. I realise that this past winter was cold and the CVV hoses crack with age. At this rate, I'll never save up enough money to replace the X3 next year :(


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