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-   -   Misfire E53 2001 X5 3.0i - P0300, P1349, P1347 (http://forum.e46fanatics.com/showthread.php?t=920649)

Dare32 05-09-2012 07:51 AM

Misfire E53 2001 X5 3.0i - P0300, P1349, P1347
Hello, I am posting this tread in hope to find resolution for the issue that I have and to help in future, to everyone who might face same problem.
Here are details on what was going on and how I got these codes. I am not sure if this is related but it is better to mention all the details.

First I couldn't get the inspection sticker as two monitors were not getting ready 1. evap 2. secondary air. I was reading thru many posts and I found valuable information on how to check specific part or system functionality. Because BMW dealer told me not to bother with EVAP, (MA allows 1 monitor not to be ready) and that SECONDARY AIR should be fairly easy to fix, I started on checking secondary air for simplest first as that was suggested by many on this site. I found vacuum lines to be brittle because of the age and exposure to temperature change, so I replaced two pieces, one on the SAP (Secondary Air Pump) check valve, and the other on the back of the engine, on the other side of that same plastic pipe. I also replaced check valve, oil separator (PCV valve) with all hoses. At this point car was working fine, I just coudn't get the monitors to set. Then after more reading and checking I found running valve (DISA) to be broken so I replaced that with new one. I found O2 sensor (Bank 2 sensor 1) to be slow and replaced that too. At this point car started misfiring. I rechecked and rechecked and I can't find anything that I did wrong, unless DISA is bad, which is not likely. Because I get random missfire P0300 and specific cylinder P1349 (Cyl 4 misfire with fuel cutoff) and P1347 (Cyl 3 misfire with fuel cutoff) I tried replacing spark plugs 2 times, swapping coils between 3 and 6 and 4 and 2 and nothing would change these codes. Now there is interesting thing, I don't get codes if I disconnect MAF sensor. What does this mean?

Dare32 05-10-2012 02:58 PM

I see, no one can figure this one out.
Anyways, I'll keep posting until I find resolution and hopefully help someone else.
I tested everything I could,
1. plugs and coils
2. Gas supply pressure and swapped injectors
3. Vacuum is holding
I don't know what else to do.

Also I hooked up my scope to input wires on coils and I was wondering what I am looking at.
Can anyone explain what this might be?



toxicg35 01-24-2013 01:14 PM

Did you ever figured it out what was wrong with your car?? im having the same problems with my x5 and im tired of putting money into it.

Dare32 01-24-2013 03:18 PM

Yes, I found what was wrong...
After almost 6 months of searching, reading, testing, I found small leak between cylinder 3 and cylinder 4. So the leak is from one cylinder to another, no other systems involved so I had no problems with oil, coolant or leak outside.
It was internal leak only and that was determined with the "leak down" test. At this point there is no way to see inside and figure out where is leaking but it's one of the 2 things. Or is cracked head or blown gasket. Many will say gaskets are not going bad on these cars as they are layered metal plates, but that was exactly the reason for this fault. Take a look at the photos. I had to take the head off, resurface it, replace head gasket and other parts when I was at it.
Car is now like new, but taking those exhaust nuts off was pain in the *ss.


I hope this helps, and by the way the original issue, before it started to misfire was O2 Sensor PreCat bank2. It was too slow and once replaced secondary air would get ready on first trial.

Good Luck

toxicg35 01-24-2013 03:45 PM

ok well let me ask you this, does your vehicle was misfiring all the time?? when cold/hot?? because what mine does is that you could drive it for like 20min then check engine turns on and thats when it starts to misfiring but when this happens i turn it off and turn right back on its fine for an other 30min, also when misfiring and disconected the MAF runs fine, i bought an other used MAF thinking that it could be the problem but stll does the same thing.

Dare32 01-26-2013 02:39 PM


my car would misfire only on idling <1000 rpm after only 30 seconds. Because this is manual transmission, I could drive it all day without getting into the "mode".
For example: If I just start the car, when is cold, it would take time to heat up and as soon as rpm's get down to about 800, it would start misfiring.
If car is hot, it would start misfiring within 30 seconds.
But if I keep gas pedal pressed so rpm's are above 1000, it would never misfire, as computer wouldn't complain, and I believe that's because pressure in cylinders are much higher than while idling.
Misfire was because of the fuel cut off by computer, and that was because computer sensing slight misfire, so to protect the cats, it cuts the fuel on those cylinders. I hope this helps.

Sameuro 02-01-2013 10:06 AM

My car misfires only during idling and once the needle settles, I restart the car and it goes back to normal? Does any one have an idea what this is? I got codes for cylinder 2,3,6 misfire and mass air flow. I changed all those parts plus my plugs but, still no difference. I don't want to waste any more money, does anyone experience the similar issue? Is it a vaccume hose leak or seal? No one can figure it out.

Dare32 03-05-2013 12:44 PM

Sameuro, have you fixed it?
If not I would go after the vacuum leak as it's fairly easy and cheep thing to do. Let me know if you need help.

Dare32 03-05-2013 12:54 PM

When MAF disconnected, ECU default values are used instead of real reading from the MAF. At this time you could have increased RPM's and/or other parameters changed so ECU is not complaining. If you drive the car and it starts misfiring at random times (after20,30,50min), it could be that needs to run for specific period of time in certain RPM range. For that reason it's best to test the car while there is no load (or almost no load) in parked position. Test it on idle speed and see if it starts misfiring and repeat the measure if it does.
If not try raising RPM's to 2k for couple of minutes and see if that's going to do it or fix it.
Let us know

Sameuro 03-05-2013 01:19 PM

Well it only misfires when I start it in the morning, before the needle settles it starts up ok and it would run fine for a bit but, once the car starts warming up the rpm needle settles. When the starts settling, it starts misfiring and my engine light comes on so I wait for my temperature needle to increase and when it increases by a bit, I restart the car and it runs perfect; the misfire suddenly stops but, the engine light remains or sometimes it will turn off. It's the oddest issue I've ever encountered.. I'm thinking it might be a vacuum leak or at least I'm hopping.

Dare32 03-05-2013 02:51 PM

I think next step would be to get those codes and post them here. Also if you could clear the codes, once car is hot and see if they are any codes coming back. Record those so you know which codes are actually causing the light to come on when car is hot. Also it will turn off on it's own after so many miles made with no fault registered, but if it's coming back, that means there is problem that needs to be fixed. Even if light is not on, it should be stored in ecu memory, so you should be able to read them.
for long time I couldn't figure out how to test the intake for leaks. It is actually simple thing to do. I remove air filter and housing. Then I remove MAF sensor and put the plastic bag over the boot with some elastics so it's air tight. It doesn't have to be strong as we talking about small air pressure here. Then I remove the service cap, it's the rubber cap on the service port on back side of the intake manifold. (Let me know if you need photos). I put hose about 3-4 feet long on the port so I can start blowing some smoke into it. This is the time where you open beer and light up your cigar or cigarette :). Blow some smoke into it, you should feel pressure buildup. close the end of the hose with your thumb and hold for 10 seconds. when you let it go it should push some smoke back, if it doesn't, you most likely have leak somewhere. If leak is big enough, you will notice where is coming from, as smoke will start showing. Let me know if you need more help.

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