Possible idle control valve diagnosis or something. (Solved)

[stevelp99]

Ok so this morning after getting to work I was met with reduced emissions, car still running fine, I'm not able to pull codes yet as I'm at work, but at lunch I turned on the car and got increased emissions and reduced power, it felt like half of the cylinders were shut off. I had an instance like 3 weeks ago and it went away, the codes pulled then we're misfire 5-8, impairing emission on cyl 5-8. After clearing the codes we did pull precat o2, but that code went away. assumed it was bad fuel as the symptoms went away. But it's back again 3 weeks later, are there any other signs or codes that would point to idle control valve? I'll be taking it to my Indy tech after work for further diagnosis. Any thoughts or suggestions are welcomed, but as of now I'm thinking idle control valve

[JDM_CL9]

Could be throttle actuator on the bank where Cyl. 5-8 are. What's your mileage at?

[vsix]

Allright do me a favour and tell me if it is the same pre cat CEL as mine, this morning.
Here's the link. Did the OBD reading with Carly.

http://www.m3post.com/forums/showthread.php?t=1193871

[stevelp99]

The engine was replaced 1,500 miles ago under BMW before I bought it. Which is why I didn't go directly to throttle actuator, unless those were swapped from the old engine which had 30k on it. I'll have the codes in an hr when I go drop off the car

[vsix]

I will swap the O2 sensors tomorrow, to see if the CEL will also move...if it's not moving my cat went down south.

Best bet would be to just show us an screenshot of your CEL.

[JDM_CL9]

Originally Posted by stevelp99

The engine was replaced 1,500 miles ago under BMW before I bought it. Which is why I didn't go directly to throttle actuator, unless those were swapped from the old engine which had 30k on it. I'll have the codes in an hr when I go drop off the car

They probably just replaced the short/long block and reused all the accessories/parts.

Originally Posted by vsix

I will swap the O2 sensors tomorrow, to see if the CEL will also move...if it's not moving my cat went down south.

Best bet would be to just show us an screenshot of your CEL.

Are you checking the Pre-cat O2 or After-cat O2? The Pre-Cat O2 sensors will not tell you if your Catalytic Converters went bad.

[stevelp99]

Got same codes as last time with increased emissions. Got a reduced power once this morning, but drove to my mechainc fine with just the SES light on.
2729 o2 sensor coast mode before cat bank 2
2b39 misfire with cutoff cyl 5
B2a3 misfire with cutoff cyl 6
2b3b misfire with cutoff cyl 7
2b3c misfire with cutoff cyl 8
2b41 misfire with cutout multiple cylinders
2751 oxygen sensor pump fault current cable before cat, bank 2

It to also be noted that lat time we swapped O2 sensors to see if it changed anything, it did not. We concluded last time that it may of been bad fuel as the issue went away.

Another note, when letting off the gas in say 4th gear, then reapplying gas there was a small noticeable blip of revs before accelerating, kind of like what you you would see with a downshift bit not as big of rpm jump, maybe like 100rpms but definitely a slight delay.

Last time the o2 sensor fault went away after clearing, keeping only the misfires, reduced power, increased emissions.

My tech and I believe it's either the idle control or one of the pipes associated with that have collapsed or bank 2 throttle actuator, I'm leaning toward the actuator now. I'll know more by tomorrow afternoon as they're just starting to tear down and check things out.

[Rat3d ///M]

My guess is bad o2 sensor or throttle actuator. I lean toward o2 sensor because of the o2 sensor faults. My throttle actuator just went out and I had the same thing, but no o2 sensor codes.

That being said, what's with all the throttle actuator cases lately? Ever since mine went out, I swear I have seen 10 cases within the last month.

[stevelp99]

Ok, I finally got my car back, I ended up having to take it to BMW as my independent couldn't figure it out, but I think I figured out what he missed. It was the O2 sensor, and BMW only figured it out after it finally got bad enough to throw another code, O2 adaption limit error and O2 sensor coast mode. They were only seeing misfires when I initially took it in. The other O2 code I got before only showed up once and went away which is why my mechanic and BMW didn't really pay much attention to it. I also think when my independent mechanic tried swapping out the pre cat O2 sensor, he either got a bad o2 sensor out of the box, or forgot to reset the O2 sensor adaption. Either way 750$ later it back and running smooth. I took it on a little joy ride tonight to make sure it was all functioning, and starting up properly at cold and hot start, all is good.

Thanks for help, input, comments and what not.