Help diagnose stumbling idle

[rowsdower]

2011 N51 128i

I just had AA headers installed by an indy. When my car is cold, it idles and drives fine. Once it warms up, it starts surging at idle from 600-800 rpm. Sometimes it will dip below 500 and back up to over 900 and the car shakes pretty bad.

I cleared codes with Carly, then immediately got three:

002F83
:ignition angle at idle, cold start: Too early ignition / ignition timing at idle, cold start: firing angle too early / engine turn-off time / Motorabstellzeitermittlung

002C3A
02 PreCat sensor system check, bank 2 / Lambda probe front catalyst 2, dynamic / LSU dynamic too slow Bank2

00A6CF
:Short circuit to positive or open circuit (AUC) / internal error of the sensor - K-LIN 6 xAUC sensor

Pretty sure that last one has to do with the air recirculation feature and I'm not too concerned.

As far as I can tell, the precat sensors are hooked up correctly. It could be that they dropped the bank 2 sensor and it's no longer working (not sure). The pre and postcat sensors appear to be hooked up right. They put silver paint on the connection on one of them, and both halves still have silver paint so I'm assuming they are plugged in correctly. That does not mean they didn't accidentally swap the leads bank to bank before reinstalling, so I guess I could have a problem here.

Same behavior on the stock tune and the BPC tune that I installed after I got home so I think it's mechanical, not tune related.

I tried resetting adaptations using the throttle method, and unplugged the battery for about 30 minutes.

The first code sounds like something with ignition timing but I don't know what would cause that. Maybe a bad coil?

My only other thought is they washed the engine without the plastic cover that sits over the valve cover so there may be water in a connection or a coil.

Any thoughts on where to begin troubleshooting?

[Bimmer-Bob]

Are you running any software with the headers? You'll have problems if not, and will eventually get a CEL (it took about 200 miles before it showed up on mine, but I had the weird surging idle). In any case, it takes a while for the car to adapt to the new fueling parameters, I guess. I remember when I first did the headers the idle was quite bad, especially with the stock ECU software.

Even now, after a couple of software iterations, new eccentric shaft sensor, plugs, and coils, I still get an occasional idle fluctuation, although not as bad as before. I last threw a code I don't recognize (2DF1?) and my next guess is maybe to try and swap out the VANOS solenoids - but otherwise I'm not too concerned.

[rowsdower]

Originally Posted by Bimmer-Bob

Are you running any software with the headers? You'll have problems if not, and will eventually get a CEL (it took about 200 miles before it showed up on mine, but I had the weird surging idle). In any case, it takes a while for the car to adapt to the new fueling parameters, I guess. I remember when I first did the headers the idle was quite bad, especially with the stock ECU software.

Even now, after a couple of software iterations, new eccentric shaft sensor, plugs, and coils, I still get an occasional idle fluctuation, although not as bad as before. I last threw a code I don't recognize (2DF1?) and my next guess is maybe to try and swap out the VANOS solenoids - but otherwise I'm not too concerned.

Thanks Bob. Yes, I installed the BPC tune and it didn't change anything. I left the battery disconnected overnight so maybe that will help? I doubt it though... haven't driven it yet.

The code about early ignition sounds like an eccentric shaft issue based on what I've been reading online. I do have INPA, but have never used it, so I may try playing around later today to see the readings on the O2 sensors and the eccentric shaft sensor to see if there is anything funky going on.

[desertman123]

Use INPA to reset all adaptations - they won't be cleared if you just disconnect the battery.

[Suhb]

Basing it off this happening after headers installation, my guess is it’s the o2 sensors. Before it’s warmed up it’s in open loops. After it’s warmed up it’s in a closed loop taking readings from the o2. I would just take it back to the shop for them to double check again.

[rowsdower]

Quick update, I flashed back to the stock tune and no change. I flashed back to the BPC tune again today and it is now running a lot better. Occasional idle hunting / almost dying issues, but drove for 15 minutes and did not get the O2 sensor code again. I did get an engine ignition code but not the same as before. I only have about 40 miles on the car since getting it back from the shop, so I'm thinking maybe I just need to drive the hell out of it. Or maybe it's temp-related... it is 32 out now, and was about 60 when I initially had problems. I'll try to remember to update this thread if the problems subside.

Couldn't get INPA to work. The hours I spent trying, I could have just gone out and drove the damn thing to see if anything changed. INPA sucks.

[rowsdower]

Well, temp was ~75 here today and I had all the same problems I had initially. The car actually stalled while idling at a red light today, so I'd say it's even getting worse. After googling the symptoms, it sounds like it may be the eccentric shaft sensor. I just checked and sure enough, there is oil all around the sensor on the valve cover. My next job was to replace the leaking valve cover gasket anyway, so this is not the end of the world.

Regarding replacement parts, I'm finding the Genuine BMW piece at $454 and aftermarket at around $200. Is this the type of component you really want OE parts for? It does not look like a particularly complex part...

https://www.ecstuning.com/b-vdo-part...SABEgIXcPD_BwE

[Nafy]

Hello were you able to fix the headers-idle issue at the end? I am having similar problem and looking for solution. Thanks

[rowsdower]

Originally Posted by Nafy

Hello were you able to fix the headers-idle issue at the end? I am having similar problem and looking for solution. Thanks

Nope.

[Rmtt]

Originally Posted by Nafy

Hello were you able to fix the headers-idle issue at the end? I am having similar problem and looking for solution. Thanks

Does your car have the N51 or N52 engine?

Just questioning to see if this is a problem showing across both platforms, or one in particular.

Thanks.

[Nafy]

I have n52 2010 e90

[Rmtt]

Originally Posted by Nafy

I have n52 2010 e90

Thanks.

This sucks as I have a brand new set of AA headers in my office waiting to go in. I was planning in doing them last anyway. But if this seems to start occurring to more and more people, I may end up selling them.

But I've also seen the flipside where a lot of people were running them and having no issues.

[asbrr]

Originally Posted by Rmtt

Thanks.

This sucks as I have a brand new set of AA headers in my office waiting to go in. I was planning in doing them last anyway. But if this seems to start occurring to more and more people, I may end up selling them.

But I've also seen the flipside where a lot of people were running them and having no issues.

Are you close to/near BPC? That would be the ideal scenario, get them installed and tested right at BPC so they can help diagnose any issues.....

But your point on other people running the headers with little to no issues is valid I think....there are probably more people with cars running cleanly than not, just that we don't hear from them for obvious reasons...

[Rmtt]

Originally Posted by asbrr

Are you close to/near BPC? That would be the ideal scenario, get them installed and tested right at BPC so they can help diagnose any issues.....

But your point on other people running the headers with little to no issues is valid I think....there are probably more people with cars running cleanly than not, just that we don't hear from them for obvious reasons...

I'm about 5 hours from them. I planned to go over there to let them do my MILVS, VCG, and a custom dyno tune.

I planned to use their "canned" tune for the intake and headers. Hopefully I won't run into any issues. But if I do, maybe it won't be so bad that I still couldn't make the trip and let them diagnose it if something comes up!

[rowsdower]

Originally Posted by Rmtt

I'm about 5 hours from them. I planned to go over there to let them do my MILVS, VCG, and a custom dyno tune.

I planned to use their "canned" tune for the intake and headers. Hopefully I won't run into any issues. But if I do, maybe it won't be so bad that I still couldn't make the trip and let them diagnose it if something comes up!

Just have them do it all. I went to a random shop to do my headers and regret it every time I get in my car. If I were near BPC I'd drive it directly to them to fix all my problems. They are really helpful over the phone and I just wish I didn't live 1400 miles away. I have taken my car to a couple of local shops and nobody really impresses me.

Also, are you saying you're willing to do the headers yourself but you want to pay a shop to do the valve cover gasket? If you're going to pay someone to do something, pay someone to do the headers... the job sucks. Trust me.

[Rmtt]

Originally Posted by rowsdower

Just have them do it all. I went to a random shop to do my headers and regret it every time I get in my car. If I were near BPC I'd drive it directly to them to fix all my problems. They are really helpful over the phone and I just wish I didn't live 1400 miles away. I have taken my car to a couple of local shops and nobody really impresses me.

Also, are you saying you're willing to do the headers yourself but you want to pay a shop to do the valve cover gasket? If you're going to pay someone to do something, pay someone to do the headers... the job sucks. Trust me.

I've done headers on probably more than a dozen cars. The only reason I mentioned VCG was because I'm not sure if I trust my self with the MILVS install. If it were just needing a VCG, I would do that myself. But I would be paying them for the MILVS install which I would include the VCG with.

I've done cams, heads, clutches, etc......but they have always been done on domestic cars. I've even "flycut" pistons before with the block in the car.

But for some reason, the MILVS install makes me nervous. When you can't just unbolt something completely, and re-install.....I start thinking about what all may could go wrong when your loosining something 5 turns, removing a piece under spring tension, and trying to force a piece back into place, and then tightening everything back down again.

And doing this on a Head that I have no experience with, that is what worries me. With headers, they are pretty much the same across the board. It's a tight space, but as long as you get good sealed surfaces and O2 sensors back in the right place.....that's about all their is. And you will know if you have an exhaust leak.

But if I were to run into issues, I do have a very experienced Indy 20 minutes from me at Euro-Sports named Albert who is a BMW guru. Most people from North Carolina, South Carolina, and Georgia know of him.

He just doesn't do tuning work. But for anything else I could ever need, I would go there. He's the one who advised me about the intakes on the N54's needing to be walnut blasted among other things when I was thinking about buying one when they first came out. This was well before other people had seen the trend starting. He did all the work on my E46 M3 such as sub-frame work, valve last, etc.

So I think I'm covered in that aspect. I hate you're in the position your in. But for the life of me I can't see how this idle issue could be so hard to figure out with something as simple as headers.

[jjdajet]

I really want to get my SS or AA headers on my n51 'vert but the idle is scaring me. I'm live in Sacramento and I'm considering making a road trip to BPC to have them do a tune, MILVS, and on the fence about the headers. This whip is my daily driver you see.

[Rmtt]

Sacramento...like on the West Coast? I can't see on my forum app.

That's a hell of a road trip unless they have shops elsewhere. I thought they were only in NC.

It's maybe 5 hours at the longest for me, that's why I figured I could still make the trip after I put mine on if I do have an idle issue.

If not, I've got a good friend with a roll-back.

[jjdajet]

You're right that's on the other side of the country! That sucks man. I guess I have to find a local indy shop.