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Discussion Starter #21
Hi Op,

I have a 99 540 with the exact same symptoms and codes. From the research I have done, I am leaning towards the throttle body gasket first, which I have already purchased, just haven’t had the time to replace it yet. If anything, the throttle body gasket is the cheapest of the parts referenced above, which is where I like to start anyway.

Anyway, I guess all that to say it would be very appreciated if you could update this post with the results from whatever route you choose.

Thank you in advance,

Lance
Hey Lance,

Thanks for your reply. Although I’ve narrowed it down to many different causes, I still have not come to a final conclusion. I’ll definitely update this thread once I’ve determined what it is and the issue is resolved. Hoping it’s done this weekend...

-Alan
 

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The first thing you should do is replace your fuel tank breather valve as Sailor mentioned earlier. You have a code for it and if it's stuck open there's your leak.
 

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Discussion Starter #23
Hi Op,

I have a 99 540 with the exact same symptoms and codes. From the research I have done, I am leaning towards the throttle body gasket first, which I have already purchased, just haven’t had the time to replace it yet. If anything, the throttle body gasket is the cheapest of the parts referenced above, which is where I like to start anyway.

Anyway, I guess all that to say it would be very appreciated if you could update this post with the results from whatever route you choose.

Thank you in advance,

Lance
Got the car diagnosed by a BMW Indy shop. Faulty Intake Manifold Gaskets.
 

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Discussion Starter #25 (Edited)
Hi Alan,

Thank you for the response and information. If/when I ever get around to replacing my TB gasket, I’ll report back here. Good luck with your repairs.

Lance
Thanks Lance, I need the luck!

Unfortunately, I am still back to where I started. The Indy shop I went to smoke tested my car and showed me the vacuum leak. The smoke came out of the gasket in the front of the intake manifold. It was ONLY this gasket... I saw with my own eyes that this was where the leak was. I went ahead and bought the front gasket and throttle body gasket (Genuine BMW parts from FCP). I removed the throttle body, cleaned it thoroughly and swapped the gasket. I removed the front gasket on the intake manifold and installed the new one, put everything back perfectly after cleaning it all.

The car is driving better but is still "puttering" or "Hiccuping" at idle. It is driving me insane. I used my code reader to run live data and verify that there is still a leak but there is simply no way it is at the front of the throttle body. I completed the work flawlessly and meticulously. I am a little confused as to what is going on but I am looking to do another smoke test myself to locate the other vacuum leak. I suspect it may be the rear gasket and CCV.

As this issue is STILL not resolved, I will report back here as well....

EDIT:

I was also told by the shop that smoke tested it:

"we usually recommend the intake gaskets at the same time because its a common failure item and it often doesn't show up on the smoke tester unless you catch it at the exact temperature which can be challenging. we always recommend the rear PCV plate as well because those can fail intermittently and not show up during our diagnostic. Finally, the engine Ecu has most likely adapted to the large vacuum leaks and it will take some time for it to re-adapt the fuel mixture now that you have repaired a large leak. this can take a few days of driving unless you have a scan tool which can reset those values. even after resetting it still takes some time to re-adapt but the process does go more quickly this way. "
 

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Hi Alan,

So sorry to hear your problem remains, but the 2 gaskets you did do obviously needed changing, so at least the time and effort wasn’t for naught. Although very frustrating, it isn’t a stretch to think that the prone-to-leak when old intake gaskets, which are probably just as old and heat-cycled as the TB gaskets you witnessed leaking and thus replaced, are a likely accomplice, if not one of the main suspects. And in my experience, the more frustrating something is, the better it feels when you finally do figure it out. So here‘s to depositing into the feel-good bank of future success, lol.

However, I would probably look into the fuel tank breather valve as mentioned above next, and definitely would if you still have a code for it.

Fortunately, my car only does it until it is fully warmed up, and only in sub freezing temps. However, I am sure it will get worse with time, which is why I’ll be following this thread.

Sorry i wasn’t much help, but thanks again for the update. Wishing you the best.

Lance
 

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Discussion Starter #27
Hi Alan,

So sorry to hear your problem remains, but the 2 gaskets you did do obviously needed changing, so at least the time and effort wasn’t for naught. Although very frustrating, it isn’t a stretch to think that the prone-to-leak when old intake gaskets, which are probably just as old and heat-cycled as the TB gaskets you witnessed leaking and thus replaced, are a likely accomplice, if not one of the main suspects. And in my experience, the more frustrating something is, the better it feels when you finally do figure it out. So here‘s to depositing into the feel-good bank of future success, lol.

However, I would probably look into the fuel tank breather valve as mentioned above next, and definitely would if you still have a code for it.

Fortunately, my car only does it until it is fully warmed up, and only in sub freezing temps. However, I am sure it will get worse with time, which is why I’ll be following this thread.

Sorry i wasn’t much help, but thanks again for the update. Wishing you the best.

Lance
Thanks for the words of encouragement Lance, I needed the good energy.
My car was where yours is now....4-5 months ago. I’ve done a lot to the car since then but It’s a constant labour of love with old beamers.

I will update this thread once this is fully resolved.
 

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Hook up your scan tool and run the fuel trims again. If the trims are normal then you may be good. If they still show the ecu is adding fuel you still have a leak.
 

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Discussion Starter #29
Hook up your scan tool and run the fuel trims again. If the trims are normal then you may be good. If they still show the ecu is adding fuel you still have a leak.
Percentages are negative at certain points, not sure what that means....Here it is:

Live Data

Very much appreciate your knowledge and help on this xrviz. Thanks
 

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Thanks for the words of encouragement Lance, I needed the good energy.
My car was where yours is now....4-5 months ago. I’ve done a lot to the car since then but It’s a constant labour of love with old beamers.

I will update this thread once this is fully resolved.
You are welcome Alan!

Well looks like I’ll have to dig into my motor again pretty soon. The last time was just over a year ago to put in Raj’s vanos seals and upon getting ready to put the upper front timing chain covers back on I noticed a piece of broken off timing chain guide plastic about 2 inches long not attached to its guide rail anymore and thus precariously balancing just above where the chain and bottom gear mesh.:oops: Sufficed to say, that added a minute and a few more shiny pennies to that repair.

I‘ll keep sending good energy that way, and you are so correct, a labor of love for sure!

Lance
 

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Your fuel trims are completely different now. The negative numbers are the ecu pulling fuel as it readapts from the long term fuel trims that were adding fuel. I agree with your mechanic, either keep driving it and let it readapt. Or if your scan tool has reset adaptations function you could do that.
 
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