X loves the cold, hates it warm
 

I have been battling a particular issue for about 8K miles now and can't figure it out. I searched on here for a similar issue but no luck.

When it is cold outside (below 50 degrees), my X runs almost perfect. It will stumble at idle a few times at start-up and a few times at the beginning of take off from stop, but otherwise it will accelerate and cruise with no stumble and no SES light.

When it is warm outside (between 50 and 70 degrees), more stumbling at idle and take off and an intermitent SES light.

When it is hot outside (over 70 degrees), rediculous stumbling at idle and take off and constant SES light. The hotter it gets outside the worse it gets to the point where the stumbling will shake the entire vehicle constantly and will hamper acceleration to the likes of a really fast bicycler. The only way I can get it to stop is to turn it off and restart it.

I have pulled the codes in hot weather and get the non-specific misfire code. I've been putting off fixing it since it has been so cold but it is about to get warm again and it will be a pain to drive.

I have checked the DISA valve, it's fine. I don't believe I have an intake leak, none seen. I was thinking O2 or MAF because of the effect of outside temperature but I don't like playing part roulette. Anyone heard of this before?

Part roulette or not, I think the MAF would be a good starting point. Cleaning them is pointless. Do you have an aftermarket intake or filter? If you've got a misfire on all cylinders, random ones, or just one bank (1-3, 4-6) would be helpful information for helping to diagnose the problem.

Intake and filter are OEM, P0300 is the code I get which from what I could find out about it is a random misfire.

I just recently got back from NTB for an alignment check and they gratuitously pulled the codes because it is warm today and SES Light is on and they told me I have a vacuum leak. I asked for more info like where is it leaking from and they could not tell me. They asked if they could charge me $88 to hook it up to the smog maching. This didn't sound too bad to me but I wanted to report back to the forum for what you guys might think a good place to look first would be or if this sounds reasonable. I'm also going to do a search on the forum for vacuum leak culprit areas.

Any ideas are greatly appreciated!

$88 is a bit steep for something that literally takes 10 minutes tops (I have one), but I guess it is what it is.

I have had similar problems on older cars (different make) back in the day and it was due to a vacuum leak.

Thanks guys! I'm going to give it a good looksee. If I can't see anything, I'll start replacing hoses until it starts running right . . . starting with the cheap ones first of course. Hopefully Vineyard wants to buy it, he's looking for a 3.0 sport and I'm getting tired of working on this thing.

At least replacing hoses is cheap, and isn't really a waste either. You've got low mileage, but it's also 7yrs old, so it's can't hurt.

Leaning towards the MAF myself.... if ambient temp is the only change that gets you a fault.

I was thinking MAF too for the same reason but like m5james said the hoses are a cheaper place to start. I'll knock it out this weekend and report back. Hopefully this thread will help someone else out down the road.

You just gonna replace the hoses and skip the smoke test all together? For the cost and small amount of time it'll take, doing the hoses won't hurt regardless. I had a lingering misfire on my 7, and eventually found it on a brakebooster line, and inside of one of the Z folds, the inner corner had a hairline split that came wideopen once I pulled the line of. Good luck and keep us posted.

Any luck Repoman?

Not yet M5james. I intended to climb under the hood last weekend but cold snap came through so it ran good in the cold + it was too cold to climb under the hood.

Had to reschedule hood opening for tomorrow. I will report back with my findings.

OK finally got to tear into it, most/all hoses looked fine. I bent and twisted everyone I pulled and they seemed fine. However, the infamous elbow intake boot with the little slinky hose coming off of it showed moderate cracking on the outside of the bend which I'm sure is allowing some unmetered air to enter. Could that be the cause of my misfires? BTW, codes P . . . 1345, 1347, 1348, 1352, 0300 and 0313 are what the computer gave me.

Also, while inspecting my DISA valve during removal I found that the flap would open and close w/o any spring tension. I pulled the little cover off of the side of it and saw that the shaft from the plunger was not hooked on to the valve wheel. I rehooked it and it seems to be springing like it should now.

Going to go get a new intake boot and hope that is the problem. Going to reinstall DISA and hope it is fine.

:worthless:

What would you like a picture of? I'd be happy to snap a shot of what you'd like to see.

BTW, I just got a new Y-pipe but it seems just as flimsy as what broke on me in the first place. Has this part been updated by BMW or is it the same part that is destined to fail on me again? Is there a better aftermarket part w/thicker rubber?

I like taking before/after pics for those who like to see what I'm talking about when I do repairs, upgrades, etc. Maybe take some shots of the DISA valve and where you had vacuum line problems so other's can look in case it happens in the same areas on other vehicles.

10/4, I'll snap photos tonight to show before and afters, also will snap photos of my 6 oil puddles sitting around each coil. Pics a comin.

Pics below:

1st pic--old and new y-pipe. It is easy to see the poor design and why they all split. The rubber should be molded in the shape of the bend on the small pipe, instead it is molded straight and must be stretched into a bend permanently to be attached to the manifold. Add a little heat and you've got splitola.

2nd pic--splitola of the old y-pipe.

3rd pic--DISA valve what I saw when I noticed no movement of the butterfly, arm not hooked to butterfly shaft.

4th pic--DISA valve repaired by me, hooked arm back up to butterfly shaft to regain butterfly movement.

5th pic--see the pools of oil around each coil collected in the partitions.

Pics were taken at night so may be a little crappy, can retake tomorrow in sunlight if needed.

Yeah, that is a poor design for that little neck.

I've read somewhere about how people have been able to fabricate something in order to prevent the DISA valve arm from popping off again.

That is quite the puddle you've got there.

So is anything running perfect again?

Too late to install it when I got home tonight, going to put it on in the morning and report back. I also learned that the puddles of oil are probably from a cracked valve cover that can only be seen from the inside of the cover when taken off. If that is true I'm going to be sooooo pissed.

Well got the new y-pipe in this morning and got it all back together. On initial start up, lots of stumbling like usual but it seemed to get better as I let it idle. It idled for a few minutes w/o stumble then I took it for a quick run around the block and still seemed fine. Put it back in driveway for 15 minutes and started again, no stumbling. Backed out of driveway and put it in D, as soon as I touched gas pedal I got some minor stumbling but it went away again. Do I need to reset anything after doing this. It seems much better but still lurking. Or will the computer correct itself after a few miles? I cleared all codes and will drive for a while to see if they come back.

On another note, doing this repair showed me that I have a valve cover/valve cover gasket issue and also while underneath I saw a few chunks of grease on lower control arm so it appears that my driver side boot is giving way. First one at 55K, second one just short of 65K.

So what was the verdict on the DISA valve?

I'm here in Houston too and have been having a boatload of trouble since it's started warming up... I've got the 1800-2000RPM whistling, misfire codes, crap acceleration and rough idle on my '02 3.0i... I've checked the boot and that looks kosher, so I'm leaning towards the DISA or a MAF that is going out.

PM sent

Well I got the new boot on there and repaired the DISA valve but really didn't have a chance to drive it before I discovered fails with a window regulator, front cv boot and valve cover at the same time. I had it in my garage for a week waiting on regulator part. Got the window fixed, now waiting on new half shaft assy and pricing a valve cover/gasket now. I have driven a few times since and same old crap . . . just like what you've got. Misfire codes, rough idle, crap acceleration and still a whistle.

Evidently I've still got a vacuum leak evidenced by the whistle . . . probably around that crappy seal on the DISA valve. Sounds like you've got a vacuum leak too. I wanted to get that fixed first before I started spending more money on hard parts. I was thinking of doing one of those smoke tests because I've been through every other hose on the damn thing and didn't see any problems.

One method of finding vacuum leaks is to use some WD40 spray or an unlit propane torch. You selectively spray the WD40 around possible vacuum leak areas, or hold the unlit propane torch nozzle, and if there is a leak in the area, you should hear a change in the engine speed when it sucks some of the WD40 or propane gas into the intake system.

Of course, since the vacuum leak you are looking for is after the MAF, do not spray WD40 into the intake system ahead of the MAF, as it could potentially foul the MAF.

And yes, I know this is a shade tree method and that hooking it up to a smoke machine is better, but this is a cheap alternative method that typically is quite successful in finding leaks.

Vacuum leak somewhere on the intake side or idle control valve. Sealed when cold and as it warms up becomes more pronounced? Check your oil separator hoses, they could be mush back there. My .02

I have suspected that my oil seperator has crapped out. How strong should the vacuum be when you pull the oil cap? It seems pretty strong to me.

So, what happened here? Was it the Disa and Hose that fixed your issue?