[riso1988]

Originally Posted by riso1988

Solved!

I performed the smoke test and ruled out a vacuum leak. Frustrated, I pulled the throttle body. It looked pretty clean (cleaned it probably 40k ago) but under the valve it was dark/dirty. Also I had a leaking valvetronics motor gasket so I replaced that.

Put it back together and have a steady idle! No more hiccups/surges during idle. Assume it was the throttle body cleaning but maybe the leaking gasket was influencing oil pressure?

Only issue now is it's still a little rough on a complete cold start for a second or two. Can live with it for now, going to try and replace the oil filter and see if that changes anything.

Well that wasn't the root of the issue. About a week or so later the idle hiccup / roughness on cold start came back.

I read a bit more about the DISA valves in the 330i's 3-stage intake manifold falling apart and clogging the intake so today I bit the bullet and pulled the IM to take a look. I couldn't believe it! The flap from the outer large valve was spit in 2 and in the head, almost down to the valves! I pulled it out, installed a new DISA and it's smooth as butter.

Hope this helps someone in the future!

[ro881e]

Well fuck me... People always talk of this 'theoretically' happening but this proves it. That was so lucky! Good catch my friend.

[2one3E90]

Hows it running AND WHERES THE PIN? WHATS THE NUMBER ON THE DISA VALVE? ITS EITHER A METAL ONE OR PLASTIC!

[stephens_7112012@yahoo.co]

We have the same problem, 1 and 4 keep coming up, it was the injectors. We would delete and they will come back, it will just get worse so we purchased injectors.

[riso1988]

Welp, the idle surge/hiccup is back again. Not sure if it’s a separate issue, the new DISA fell apart of the pin from the old DISA dislodged and is loose somewhere. Will probably pull the intake again when I get some time.

If anyone has any suggestions of other potential causes for the idle jolt/surge I’m open to hearing!

[2one3E90]

Lol happened two weeks ago. Replace two coils and all good

[fodder031]

Just came through a similar situation. Misfire started popping up, swapped plugs. All was fine, week later misfire came back. Pulled coils and found the smallest imperfection in coil 2. All better for about a week.
Suddenly, starting was an adventure, car bucked and spit. Valvetronic codes .
Unplugged the valvetronic sensor car ran smooth on shut down it was not as smooth as usual.
Not sure which to replace and due to cost, went to a u'pull lot in town and pulled valvetronic motor and valvetronic sensor from an older model. Replaced motor first, same issue. Swapped the sensor plugged it in an all good.

[rt7085]

I saw this thread and I wanted tell you how I finally fixed the rough idle issue as shown by the OP. I had the same symptoms on a WARM start (but not particularly a COLD start). And during a little driving or even after a simple bit of revving, it would stop. Sometimes when the engine was not fully warmed up it would start rough idling at the first red traffic light, especially in the winter (in New England) when you start from a much lower initial temperature; warm up takes longer.

I replaced the tank cabin canister purge value a while back. I had a suspicion that this could be causing these rough idle issues. I had bought cheaper than BMW OEM "URO" replacement part before (RockAuto), put it in and ran the DMTL tank leak diagnostics test in ISTA+ and it failed again. I knew it was the valve because when I "blocked" the old valve with a rubber stopper, it passed the ISTA+ diagnostic test! Turns out I had a bad part and had to return it. I was pinched in the moment and put the old part back in until I would get the new part; I needed my car the next day. Then I got lazy because the old valve was behaving a little better, probably because I tested it on the bench with a power supply, cycling it a bunch of times and blowing through it. I thought I simply cleared it.

One year passed. Then recently I got an engine light for a DMTL 'minor tank leak detection' (P0440) by the DMTL diagnostics. I knew that it had to be this valve again. Bought an original BMW version this time. I also started having this issue where the car would not start after a tank filling! That was new. I sometimes had to crank it 4-5 times to ECU timeout at the gas station. The valve was stuck open. This caused the DMTL leak, and moreover, the fuel vapors that were pushed out of the tank when filling it up, ended up in my intake volume. It basically was close to "flooded" albeit that it is just a super saturated hydrocarbon charge (not liquid fuel!): no air/oxygen, so no burn/start until the pumping of the engine pulled enough oxygen back in. Interesting.... By the way, when the valve came out it was nicely fully closed and seemingly operating to fool me. Not this time! See picture of the old valve on the unit where I stored it :-).

I replaced it today (in 15 min when you have done this before albeit that it is in a terrible location). Ran the DMTL ISTA+ test and in now passed. And... the rough idle, which I had sort of ignored and forgotten about by now was also gone. Filling the tank is again without problems.

The rough idle makes sense as the ingress of fuel vapors during the shorter warm start phase will disturb what the ECU 'thinks' it has for a lambda value, e.g. what it reads from the MAF. It goes 'lambda control closed-loop' fairly quickly at warm start while not at cold. Especially when the valve opening fluctuates a bit I suspect, but I could not confirm that. It can also be that the ECU is trying to correct for the error it observes with the O2 sensors and its own time constants cause the 'hunting' fluctuations. There appears to be an ECU software update for this, but I do not have that installed.) Anyway, engine idles super clean right now. Also, it explains that revving the engine may stop the fluctuations as the vacuum pulses purge the carbon canister (which should be close to purged already on a warm start). No excess fuel vapor enters the throttle body to confuse the ECU after that and the ECU is happier.

Be sure to replace the throttle body gasket when you are at it. Bolts go in with 9 Nm on the throttle body.

I hope this helps somebody out there. I see reports on this kind of issue a lot with people trying to replace half their engine to fix it. As is evident from this thread as well.

[riso1988]

Just an update - took the E90 on a 2K mile road trip, mainly highway driving. Has been fine ever since (month or so). Wondering if it was a carbon buildup maybe?

[Ehdez99]

So I just did an oil pan gasket replacement myself for the first time and well it went how'd you expect, something went wrong but before anything I had just changed the gasket on the valve cover and oil housing filter gasket. So I'm pretty in getting this 328i running good. It's an 08 328i n52. I got it non operating and I since changed the starter and the crankshaft sensor, spark plugs changed coils works probably need new ones and today I finally finished the oil pan gasket. And when I started it i it felt good for a minute then total failure and it dfrjbtuhry started shaking. I started it a few times after that to see if went away obviously I'm not that smart to know when something went wrong. So I have the car lifted I don't know what I did wrong. I had to pry the oil pan off but nothing was broken or at least I think. Could I have hit the engine from the bottom and messed up the engine completely. It had all cylinders misfires 1-6
And some other could like exhaust crankshaft, something about the solenoids and I just got the car at 208k for 1100 so I'm trynna see if any other things I need to change to keep this 3 series running. Anyone can tell me if I might've had a sensor disconnect or a fuel line maybe ? I did see a tutorial on it. Pretty good if I do say so myself. My setup was similar to his. Please help!