Help with misfires
 

Hi. I have a 2001 4.4 sport (133,000 miles) that is running really rough and the check engine light flashing. It seems to run smooth until it gets warm, then the idle gets very rough and misfires. I pulled the codes and I got: P1341, P1343 and P1345. I thought maybe a good tune-up could be the culprit since its never had one. So I changed all the plugs, all 8 coil packs and both left and right camshaft position sensors. Once I finished I started up the car and it still runs rough and I'm seeing the same codes. I purchased 4 new O2 sensors and am going to try that route next, but before I ruin those with possibly more misfires is there anything else I could try? I need to get this back on the road soon so any help is GREATLY appreciated. Thank you.

You may want to check the oil separator hoses. They tend to get mushy and split causing engine misfires. See the following thread for details:

http://www.xoutpost.com/bmw-sav-foru...ause-pics.html

I appreciate the tip, but I just replaced them a couple of months ago, so it has to be something else. Ill give them a look tonight when I get home to see if they are connnected properly, but Im wondering if it has to do with the emmissions/obd since it only gets rough once the car warms up?

Check for vacuum leaks or ignition coil(s) needs replacing.

I just changed all 8 coil packs with new ones last night with no change in performance, but how can I test vacuum leaks at home? Do I need special tools?

Just checked the two oil separator hoses and they seem tight on their connections and in good shape. Any ideas? Is there a common place where there could be a big enough vacuum leak that would cause my problems? I have noticed a small amount of oil smoke from the back of the engine for a short while while it's warming up. I will be replacing my valve cover gaskets eventually but there was not much oil near the plug boots so I don't think that could be the issue. Is there something in the back of the engine that could be leaking that I have not thought of? The OSV doesn't seem to be leaking. Do you think I should do the valley pan gasket?

you mentioned the coil packs, but did you pull the plugs?? Try the plugs.

:thumbup:

Well that depends. Does the smoke look bluish at all? Is the smell like burning oil or something sweet? I already forgot in the thread, but you said a SEL light was blinking, did you ever get a chance to pull the codes? Let us know.

Rough idle can be a sign of a failed PCV valve on the back of the inlet manifold. If the hoses where bad enough to warrant changing then it a good chance the valve has failed or is failing. There is a vacuum test you could try on the rocker cover, but this needs the right equipment that the average Mechanic won't have. A lot of people in the know consider this valve to be a service item as its very important in the correct running of the car.

I know this is an old post, but did you ever fix the problem?

Yes. Apparently fuel wasn't getting to the fuel pump when I had the front end on a jack while running (I only had 1/4 of a tank at the time). Fill up your tank with gas. That was my problem. It was a simple fix for me

Never a good idea chasing a problem with new parts. Troubleshoot, troubleshoot, troubleshoot. Are there any other symptoms such as loss of power? as asked, what color is the smoke? White and sweet smelling is coolant, blue is oil, black is excess fuel.

I don't see where you have installed the new O2 sensors. The precat sensors help regulate air/fuel mixture. If they haven't been replaced they are overdue. When you replace them be sure to check for corrosion or bad wire.

The codes indicate misfires with fuel cutout. Just because codes can be misleading and it is easy and cheap to do I would clean the MAF sensor with MAF cleaner. I would do a fuel pressure test and a smoke test to verify there is no vacuum leak. Check the coolant level and see if the color is normal. You can try spraying brake cleaner around the engine, sometimes a vacuum leak will cause the engine to increase rpms for a moment. You can try disconnecting the MAF connection. If the idle does not change the MAF is not working properly.