Rough idle, 5 check engine codes

[Brian 328is]

1 month ago, rough idle, so I cleaned the ICV. I also checked the ICV for proper resistance. ICV was OK. Idle improved, but was rough now & then.

Now, very rough idle (it stalls), and 5 CE codes

P1250
P0505 Idle Control System Malfunction
P1188 Fuel Control (Bank 1 Sensor 1)
P1189 Fuel Control (Bank 2 Sensor 1)
P0173 Fuel Trim Malfunction (Bank 2)

Any help?

Brian

- - - Updated - - -

Did some web research - vacuum leaks, bad MAF, O2 sensors...

[Eric93se]

Check that the IACV hasn't become dislodged from the manifold (the grommet that holds it in the manifold). Did the arm inside the IACV swing freely?

[Brian 328is]

I unplugged the MAF wiring harness. Car idle perfect. So, I replaced the MAF with a known good MAF (sometimes it helps owning two E36's), plugged in the harness, and car idled rough!

[Eric93se]

The codes are telling you that both pre-cat sensors have to be replaced. Make sure you get the right ones, you cannot use the sensors that older E36's used. Good prices on rockauto.com 5% off code should be on retailmenot.com

[Jamie39571]

I have the same thing going on with a 1998 Z3 (M52) 2.8. I pulled 6 codes, P0130 (O2 sensor bank 1 sensor 1), P0150 (O2 sensor bank 2 sensor 1), P0170 (Fuel trim bank 1), P0173 (Fuel trim bank 2), P1188 (Manufacturer Control), and P0101 (Mass Air Flow A Circuit Range/Performance). I have replaced both upstream O2 sensors, new MAF, cleaned intake and injectors, DISA, etc. and put new spark plugs. It still idles rough, and when driving from a dead stop the car falls flat on its face with hesitation and sputtering. When it does this, I disconnected the MAF, and it runs much much better. You guys have any advice?

[Brian 328is]

When you disconnect the MAF, the ECU goes into "open circuit" mode, as opposed to using the MAF (intake) and O2 sensors (exhaust) in "closed circuit" mode. It will still run, but far from ideal, with poor acceleration.

I was ready to replace the O2 sensors, but I bit the bullet, and took it into a mechanic.

Cause: Vacuum leaks, in two places, caused by two defective hoses.
$50 parts, $60 labor from the mechanic, $110 total

At $80 per O2 sensor, a huge savings in time & money.

Brian

[zachdude1100]

^ right on. If you have a ton of check engine codes related to air fuel stuff it's probably just a monumental vacuum leak. The engine will try to read every sensor value and take it into consideration, but the computer already knows what the values are theoretically supposed to be within a margin of error. My roommate was about to go buy new o2 sensors for his Taurus when it all of a sudden ran crappily and had 2 o2 codes. Sure enough opened the hood and found a huge vacuum leak within 10 seconds, patched it up, and codes went away.