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Discussion Starter #1
Hey all,

Today I took the car out for a quick drive and noticed the CEL came on on the way home. It was city driving, no faster than 60kph. Pulled the code and I got P0491 for the secondary air pump, but not P0492. Every thread I've found people have had both codes come up, whereas I have just one.

It may or may not be related, but I started getting pending codes for P1345, seems like the car is detecting the signs of a cylinder 2 misfire when the car is in second gear and revving up to 5k rpm. This happened on Monday and I've been able to replicate the issue several times since. After the new code this morning I took the car out on several longer drives at highway speed (but not past 4.5k rpm) and neither code came back up.

Honestly I can't tell if the car is running rough at idle. It seems a little rough, but it idles at ~600 rpm and doesn't fluctuate, but the car has a slight rumble, very faint but I can feel it. I'm looking to get the spark plugs and injectors done in about 6 weeks when I can afford to do them all at once, hoping it could solve the issue. Any thoughts? Doesn't seem to be any loss of power or noticeable loss of fuel economy so far.
 

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Discussion Starter #2
Still looking for a solution to this unfortunately :( Last week I ended up getting a misfire with fuel cut off on cylinder 1 and 2, and swapped the coils but still received the same misfires on those cylinders. Car runs rough at idle, at cruising speeds but not necessarily at startup. All roads are pointing to a clogged catalytic converter, but I'm not sure which one. Either the cat at the manifold or the one further down under the front seats. Not only am I finding it tough to find anyone with the replacement parts here but seem to have options between $100-150 for a used part.

A few posts here have mentioned the CPS, but it seems limited to rough idle on cold start with misfires. I replaced Bank2 CPS earlier this year as it was throwing a CPS specific code, but Bank1's isn't new. Is it a waste of time to try the old camshaft position sensor in bank1 and hammer the throttle, or is the exhaust more likely to be the problem.
 

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Discussion Starter #3 (Edited)
Wasn't the CPS, I pretty much figured that.

Decided to try the spark plugs. Picked up two to replace the 2 problematic cylinders. Who knows when they were done last. It's hard to tell if it's reduced some of the roughness, still felt a bit rough and definitely still misfires at 5k rpm.



I think it's safe to say it has to be catalyst related at this point. Unfortunately I'm going to have to skip her trip to the BMW CCC Ottawa celebration next week, can't afford it breaking down 700km from home.
 
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