2000 BMW 528 Rough idle

MAGGIEELAINE

MEMBER
2000 BMW 528
6 CYL
RWD
AUTOMATIC
180,000 MILES

At idle car runs rough, worsens when in drive and stopped (like at a light). Seems to run ok at speed. Went to Autozone and got the following codes- P1250 (x2), P1188, P0306, P0170, and P0442.

We did change the plugs, #6 did have light oil on the threads. Several plugs (2 and 5 were the worst) had oil above the hex nut of the plug (in the coil pack tube). Some oil remained at the bottom of the tube. We're having trouble finding a place to get a gas cap, probably the dealer but I don't believe that is the issue as it seems to click properly. It is a factory/oem cap.

I'm leaning toward a vacuum issue but I have absolutely no clue where to start other than a stick of dynamite.

Any thoughts? My wife lost her job so it is shadetree mechanic time.

1 Reply

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MECHANIC
1,136 POSTS

The 1188 code is for the bank 1 sensor 1 O2 sensor code. That will cause these driveability issues. Get the cap from bmw or Bavarian auto online. Great company. You can test for a vac leak with the engine at idle spray around the engine bay and listen for rises in the rpms noting where youre spraying and that can help find it or eliminate the possibility of one. Id replace the O2 sensors if you've not done so as they are a serviceable part like plugs or belts etc. That may eliminate your problems. If not its a good place to start. Buy good bosch sensors. You should see better performance and efficiency. Call bmw with your vin for the 1250 code as its a bmw proprietary code. Ive found multiple answers for this code but still believe that most of these codes stem from the O2 sensors