[Tim603]

Hey Guys, this has been going on for a couple months. I kind of just ignored it for a while but now that I have a SMF installed the rpm stumbling is more noticeable inside the cabin at idle.

I changed the plugs around October last year after the car sat overnight and none of them smelled like fuel. I also don't think it was making this popping noise back then.

I will have to recheck the plugs soon when I get time, but based on this video, has anyone had similar symptoms? I think it is a leaky injector.

Here is a log from last month if that helps.
http://datazap.me/u/tim603/jb4-map-2-pump-flash-3-1-17


-------------------------------------------
FIXED! - see post #19 and #20
-------------------------------------------

[STR8-6IX]

Originally Posted by Tim603

Hey Guys, this has been going on for a couple months. I kind of just ignored it for a while but now that I have a SMF installed the rpm stumbling is more noticeable inside the cabin at idle.

I changed the plugs around October last year after the car sat overnight and none of them smelled like fuel. I also don't think it was making this popping noise back then.

I will have to recheck the plugs soon when I get time, but based on this video, has anyone had similar symptoms? I think it is a leaky injector.

Here is a log from last month if that helps.
http://datazap.me/u/tim603/jb4-map-2-pump-flash-3-1-17

are you throwing any codes? what brought to your attention that your injectors may be leaking? what mileage are you at?

[Tim603]

Originally Posted by STR8-6IX

are you throwing any codes? what brought to your attention that your injectors may be leaking? what mileage are you at?

No codes.
Rough Idle symptoms on startup. With newish plugs, coils and walnut blasting done 20k ago can't thing what else it would be.
115k miles.

[STR8-6IX]

Originally Posted by Tim603

No codes.
Rough Idle symptoms on startup. With newish plugs, coils and walnut blasting done 20k ago can't thing what else it would be.
115k miles.

when was the last time you changed your oil?

are you getting a fuel smell on cold starts or when driving aggressively with the window down>

it is pretty safe to say that it is in fact the injectors.

[Tim603]

Originally Posted by STR8-6IX

when was the last time you changed your oil?

are you getting a fuel smell on cold starts or when driving aggressively with the window down>

it is pretty safe to say that it is in fact the injectors.

When the video was taken, maybe 4-5k ago oil was changed. Currently brand new oil and same symptoms. I am not noticing any fuel smell.

[STR8-6IX]

Originally Posted by Tim603

When the video was taken, maybe 4-5k ago oil was changed. Currently brand new oil and same symptoms. I am not noticing any fuel smell.

it's more then likely your injectors. I suggest you replace them as soon as possible before they ruin your spark plugs. o2 sensors are also a possibility.

[Tim603]

Originally Posted by STR8-6IX

it's more then likely your injectors. I suggest you replace them as soon as possible before they ruin your spark plugs. o2 sensors are also a possibility.

Yeah that's what I'm thinking and will most likely be pulling the trigger soon. I replaced the precat 02 sensors back when I did the walnut blasting so I doubt that is it.


Has anyone on here ever heard the exhaust pop like this at idle??

[MJ80.]

So my i get like a skip or tiny little misfire at cold start similar to that, its less of an audible pop and more somthing you feel in the car, though it is similar.

I had it on my last 335 and it was leaky injectors, ive got it on my current car and just replaced the injectors and nothing has changed! Its still there.

Another thing to note is that ive been getting mad o2 codes latley and have two pre cat sensors on the way in the mail. Hopefully they fix these issues.

[Tim603]

Originally Posted by MJ80.

So my i get like a skip or tiny little misfire at cold start similar to that, its less of an audible pop and more somthing you feel in the car, though it is similar.

I had it on my last 335 and it was leaky injectors, ive got it on my current car and just replaced the injectors and nothing has changed! Its still there.

Another thing to note is that ive been getting mad o2 codes latley and have two pre cat sensors on the way in the mail. Hopefully they fix these issues.

Hmm that is interesting, how do your afr's look? They shouldnt be more than like .5 apart I think. When my pre cat 02s went bad they were way to far apart and I also had a code, once replaced it fixed that. Keep me posted on if it fixes it!

I am glad to hear someone else has had a similar issue and the injectors were the fix (at least for your last car..)

[Northwest335i]

Hey, I had the same issue. Exactly the same, I even have a video of it on YouTube.

I fixed this issue by getting new plugs I got ngk's and gapped them to 0.022". GET THE PLUGS FROM ROCKAUTO. Buy 8 for the price of 5 when compared to other vendors.

[Northwest335i]

I replaced injectors not too long ago and the issue occurred a little bit after I changed injectors. Usually if a injector is bad you will get misfiring codes when you do a WOT run or even when driving around.

When a spark is bad the car misses basically all the time. So your issue might be the spark plugs.

I would certainly try plugs before I go to injectors haha. Plus there is a new part number for injectors

https://www.fcpeuro.com/blog/posts/d...nd-13538616079

buy 937 part its cheaper and better.

[MJ80.]

Originally Posted by Tim603

Hmm that is interesting, how do your afr's look? They shouldnt be more than like .5 apart I think. When my pre cat 02s went bad they were way to far apart and I also had a code, once replaced it fixed that. Keep me posted on if it fixes it!

I am glad to hear someone else has had a similar issue and the injectors were the fix (at least for your last car..)

My Afrs and STFT is like fucke, they are in the mail so ill update when they get here, my cars running super lean.

Originally Posted by Northwest335i

Hey, I had the same issue. Exactly the same, I even have a video of it on YouTube.

I fixed this issue by getting new plugs I got ngk's and gapped them to 0.022". GET THE PLUGS FROM ROCKAUTO. Buy 8 for the price of 5 when compared to other vendors.

okay this is what mine does ^

Injectors didnt fix it, i have new sparks but my mechanic put them in and i dontknow what brand they are, were extremely cheap tho on invoice so i think next time it goes in ill get my new plugs done too.

[Northwest335i]

Originally Posted by MJ80.

Injectors didnt fix it, i have new sparks but my mechanic put them in and i dontknow what brand they are, were extremely cheap tho on invoice so i think next time it goes in ill get my new plugs done too.

Get some ngk 5992/ 95770 plugs and gap them accordingly. Car will run fine.

[titium]

log fuel trims on cold start, with any luck it'll be confined to one bank and immediately obvious. if not it's still pretty easy to spot

you need to log :

short term fuel trims (bank 1 & 2)
long term fuel trims (bank 1 & 2)
afr (bank 1 & 2)

post it up ill take a look.

[Tim603]

Originally Posted by Northwest335i

I replaced injectors not too long ago and the issue occurred a little bit after I changed injectors. Usually if a injector is bad you will get misfiring codes when you do a WOT run or even when driving around.

When a spark is bad the car misses basically all the time. So your issue might be the spark plugs.

I would certainly try plugs before I go to injectors haha. Plus there is a new part number for injectors

https://www.fcpeuro.com/blog/posts/d...nd-13538616079

buy 937 part its cheaper and better.

Good stuff right here, I will definately try this before buying injectors!! Plus I am pretty much fbo at this point so the colder plugs should be an improvement in theory.

Originally Posted by titium

log fuel trims on cold start, with any luck it'll be confined to one bank and immediately obvious. if not it's still pretty easy to spot

you need to log :

short term fuel trims (bank 1 & 2)
long term fuel trims (bank 1 & 2)
afr (bank 1 & 2)

post it up ill take a look.

I have only logged with the JB4 in the past, can I log the short and long term fuel trims with that do you know?

[Northwest335i]

Originally Posted by Tim603

Good stuff right here, I will definately try this before buying injectors!! Plus I am pretty much fbo at this point so the colder plugs should be an improvement in theory.




I have only logged with the JB4 in the past, can I log the short and long term fuel trims with that do you know?

The new jb4 software monitors the trims between bank 1 and bank 2. If they are too far off then you'll get bumped back to map 1. Just post a idle log from start up.

[titium]

Originally Posted by Northwest335i

The new jb4 software monitors the trims between bank 1 and bank 2. If they are too far off then you'll get bumped back to map 1. Just post a idle log from start up.

mhd logs are easier to read imo. worth just buying the logger module - however I'm not sure it plays nice with the jb4.

either way work out how to log all the parameters mentioned and post a log.

[seepete753]

If you are smelling fuel and getting backfires in your exhaust, it's pretty safe to say an injector went bad. I had one go on me last week and on the drive to the shop my car was backfiring like a machine gun. I would have fixed it at my house if I could manage to get INPA set up so I can finally code but thats a different story.

I managed to throw an engine code so I knew where to look. Pulled the spark plug and it was soaking wet with fuel and carboned up so badly it wouldn't fire.

I'd pull spark plugs to see if you can find a fouled plug/wet plug. That will at least point you to the offending injector. As others have said, if it really is an injector (which it sounds like) changing the plug may buy you some time but the new plug will go bad shortly too.

[Tim603]

Alright so pulled the plugs last night to change them and see what happens, this is what they look like.

Cylinder 4 plug had a small fuel smell to it and have black on the ground electrode so it looks like the warrantied injector is failing.

Cylinder 5 had a little oil on it so looks like I will probably do the VCG when I do the injectors.

07 335i (05/07 prod date)

6 - Index 2
5 - Index 2
4 - Index 8 (warrantied before I bought the car)
3 - Index 2
2 - Index 2
1 - Index 2

[Tim603]

After the plug change the car is running normal again! It does look like my injectors will need to be changed in the near future but for now all is well.

[Antetokounmpo]

that's definitely an injector issue. new plugs are just a cover up "fix" for that. same thing will happen in a few thousand miles.

[HooDat]

OP who installed your exhaust? You should take it back and have it reinstalled. one sticks out way further than the other and the passenger side exhaust tip is touching the bumper. it'll probably ruin your bumper :O just a suggestiong