06-18-2014, 01:58 PM

This is going to be a long post. I've spent a ton of time scouring over tons of posts on the various forums, but have not found one conclusive post on my issue. BUT, I pieced many, many other posts together, I solved my stubborn idle issue. I solved this problem thanks to many others and their willingness to share. This is me giving back as much as I can.
I bought my 2007 530i auto (N52) in Jan 2014 w/ 54K from a BMW dealership in greater Los Angeles. I searched for a long time for the perfect color combo and options with low miles and finally found this one. This one had sport, premium, HUD, L7, Nav, shades, PDC and low miles. The car is sweet but for one stubborn issue. It had a nasty stumbling idle after driving for 5-10 minutes, among other closely related issues. Specifically:
1) Idle would drop and shake when sitting in D or DS, after 5-10 minutes of driving. same with AC on of off. No issues when cold. One way to describe it would be to say someone lightly rear-ended me at about 2 miles per hour. The first several times, I would look in the rear view to see if someone bumped me, but no one was there. :-)
2) It never let up even after longer trips
3) Weak power and/or hesitation between 1500-3000 RPMs
4) MPG was a low 18-20 MPG
5) Moderate smell of gasoline upon start up
6) No codes, no SES, nothing from bavarian technic laptop software.
The mid to top end power was great. It shifted perfectly.
I first spent days and days reading forums and came up with about 5-10 different possible problems. I'm relatively handy, so I wanted to fix this myself..I do much of the basic maintenance, but stop short of removing an intake manifold or anything 'harder' that that. Several possibilities:
- bad coil(s)
- bad spark plug(s)
- bad/dirty MAF
- A/C compressor or recharge needed
- CCV
- too much oil
- vacuum leak
- clogged filters
- bad gasoline
- bad fuel delivery
- DISA valves
Things I did:
- Cleaned MAF
- Changed oil and all filters
- Reset adaptations (local San Diego Indy)
- Replaced Vanos solenoids (BMW strealership)
- Tricked out ECU, but unplugging MAF and driving around for a few days
- Chevron techron fuel additive
- Liqui-Moly fuel injector cleaner
My local indy could successfully replicate the problem, but could not figure out a root cause. They claim to have worked on it for 2-3 hours, but only charged me half an hour for diagnostics and only reset the adaptations. This helped a bit, but the issue came back in 2 days.
BMW stealership: The shop foreman drove it with me for 15-20 minutes. We replicated the issue. They replaced the Vanos solenoids. Issue came back in 2 days. $600 parts and labor.
I read somewhere that you could 'trick' the ECU into resetting the air/fuel trim by unplugging the MAF. This was the best so far. I unplugged the MAF, restarted and immediately felt more low end power, almost no idle shake, but MPG's sucked (in the short time I left it in that state). Of course it triggered the SES, but I shut it off with the Bavarian Technic SW. After bringing everything back to normal, idle shake got even nastier after 3-4 days. It would happen more often and with more vengeance..almost stalling out.
I did not want to go down the standard BMW path of throwing parts at it. I am out-of-warrant and non CPO. I have two little kids and I didn't want to squander their college money at the BMW parts counter.
I was about to try replacing 1 coil at a time, but that would cost me a bunch of time..like changing one every few days to see which one was bad..yes this is goofy and desperate, but I was willing.
FINALLY, thanks to many other peoples time effort, blood, tears and money, I decided to risk $330 on a new DISA valve. The outer one on the drivers side. (not sure if it's DISA #1 or DISA #2) Took me 45 minutes to swap it..Fixed. Done. Put to bed. Amen. Idle is perfect at around 600 RPMs. Low end power is back and MPGs are up.
When I took the old DISA out, it had a very small bit of oil on it and it was stuck in the open position. The new DISA was closed. I know there has been a lot of questions about what is what, so I figured I should just note that. The pin was NOT broken and the seals were all good. It seems to me that the DISA valve was simple stuck open. As I understand it, the DISA is supposed to close at the low end and open up on the high end. A stuck open DISA would perfectly define my issues.
I'm a bit peeved that neither a very, very reputable indy nor a BMW dealer could not fix this. I'm just a lowly software developer, but I was kinda determined to fix this myself without spending $$$$ on it. I didn't pay enough for the car to justify 2000-4000k bills for a single issue.
For ~$350 this is an easy fix. I assume because it threw no codes and is apparently not easy to troubleshoot, I hope this helps anyone else in the same predicament.
Chris

06-24-2009, 10:07 PM

Anyone else have a slight vibration at idle? The vibration can only be felt in the steering wheel and the shift knob. I sat in another 525 with manual tranny and same thing.
if i give it a bit of gas and raise the revs the vibration goes away. no error messages. doesn't matter if car is cold or warm.
my e46 is like a rock at idle and it's 8+ years old.
the best description is it feels similar to having the AC on in the e46 where the engine struggles a little bit due to the extra load. but in the case of the 5er I have all accessories off and the vibration can still be felt. as a passenger you would never notice it as it can only be felt through the steering wheel/shift knob. no fluctuations on the RPM either.