Never seen that in 15 yrs of fixing these vehicles. My concern would be did you have a high overheat when the expansion tank blew or leaked. Ive seen plenty of these peg red in the temp gauge for too long and take out the head gasket. See if your misfires are on cylinders 3 or 4 since the head will warp often in the middle. If you did not overheat it than its probably just a coincidence it misfired during your cooling system work.

 

The engine never overheated at all. I have the Ultragauge with an alarm set at 210, which never went off.

The car never lost enough coolant to overheat.

I noticed a bit of coolant on the ground, maybe a few tablespoons, when it first leaked. It wasn't started again until I went to move it into the garage to replace the expansion tank.

It never had an idle problem before this, or at any point yesterday after I was done. Never any codes codes before or after.

 

You are grasping at straws here, chasing ghosts.

Most likely problem is probably a vacuum leak caused by removing the air filter box and flexing and cracking the intake boots.

Need to see specific codes, Freeze Frame and Fuel Trim data.

Suggest you read my comments in this thread - http://forum.e46fanatics.com/showthread.php?p=16727145

 

I'm not grasping at anything. There is no longer a misfire. Why would the car misfire before I touched/removed anything if it was due to my touching something? Please read posts before commenting on them.

The misfire lasted for only the period of time in which there was air in the cooling system. Maybe--and this is a big maybe--it misfired while the engine wasn't up to temp yet, because I shut it off each time it became apparent that I missed air while bleeding. Even if that were the case, it cooled down and was started again after everything was fixed, without any misfiring or idle issues.

The only constant variable that was present during the misfire, as far as I can tell, was air in the cooling system.

I'm posting because it's so peculiar.

 

Vacuum leaks can be intermittent.

 

And ice cream can melt.

I'm well aware that vacuum leaks can be intermittent. What I find strange is that there has never been a misfire for the entire time I've had this car, and there hasn't been one since the air was bled from the cooling system.

As I said before, this misfire/rough idle happened before I touched anything in the engine compartment.

The misfire was only present while air was present in the cooling system. There is precedent for an improper temperature sensor reading to cause a rough idle in a fuel injected car, but I don't know if that would apply here, and I would assume a code related to a temperature sensor, not p0306 for misfire.

This is either the strangest coincidence I've ever seen (and will probably ever see) while working on a car, or it's related.

 

dude, jfoj and swordsman are trying to help you out, not be condescending or insulting. If you think the cooling system caused a misfire, then keep on thinking that. If you don't want to take their advice, then don't ask for help on a forum where people will take the time out of their day to answer your question.

Just sayin...

 

Probably the TYPICAL problem of starting the car and moving it in the driveway and not allowing it to run more than 3-4 minutes. Shut the engine off, then when restarting, the engine is partially flooded. Will have misfiring that will clear either on its own or after shutting the engine off and restarting it. This is a STANDARD feature of the E46, you never want to start the engine without driving the car around the block!

But the OP has a specific reason to think the misfires were due to air in the cooling system, so I will let him follow up on that lead as he is clearly more knowledgeable than me.

 

Too much fuel, or a battery on its way out that didn't get enough time to charge, are both common issues that could have caused a rough idle triggering a misfire code due to the car being started and shut off without time to run, and neither are features of the e46. I started and shut off the car multiple times after the air was properly bled from the system, and I've started and shut off the car multiple times in the past when switching around three cars in a long driveway with barely any space to move one if one is blocking the way. Like I said before, the only variable present for the misfire was air in the cooling system.

Where did you see me saying that it's still misfiring and there's a lead to follow up on?

FL.325.CI:

I'm well aware of the point of an automotive forum, and have myself been on them answering questions and helping people, and asking many questions, for the last 10 years or so.

There's a difference between "OMFG MY CAR IS MISFIRING BRO WHY OH WHY," and posting that something strange happened, wondering if anyone else has experienced it, and putting it out there in case anyone does in the future.

THE CAR IS NO LONGER MISFIRING. That much has been clear from the beginning.

There's a difference between not wanting advice, and pointing out that the advice doesn't make any sense and doesn't apply.**

My first post clearly stated that this happened yesterday, and that the car was started and shut off multiple times in row, with the idle improving, and the rough idle and code were gone once the air was out of the system. My first post contradicted all of the "advice" before it was given.

I should also mention here that I had to drain the coolant and remove the expansion tank again today because the smaller connection on the bottom was leaking a few drops of coolant*, and this time I jacked up the front of the car in addition to putting in on ramps, and bled the system more slowly. The first bleed worked this time, no air in the system, and no misfire. The car was started and shut off multiple times again.

*I put a small piece of wood on a jack to put pressure on the smaller connection, and lubed the o-rings with silicone.

**The response from pbotz was perfectly reasonable.

 

:facepalm:

Class of 2015/2016.

You have all the answers, why did you bother to post anything here????

Jesus Christ, look at how many responses I have, I cannot read between the lines on every post here, I am not paid enough to put up with crap like this.

I am on MANY forums and help MANY people.

You are a CLOWN to think air in the cooling system had anything to do with the misfiring. This is the TITLE of YOUR thread, right???

Your question was basically does it make sense that the misfiring was due to air in the cooling system, the answer is NO. You are grasping at straws and chasing ghosts as mentioned.

Your car is 11 years old, it is like EVERY other E46 out there, far too under maintained and you are starting the car and moving it around and basically flooding the engine. This IS a standard feature of the E46.

Do not start the engine without allowing it to run for 4+ minutes or no driving the car around the block. Then read all threads that I have started and get to work.

More reading and less posting will be a good idea for you.

Got it?

 

More reading and less posting will be a good idea for you.

Exactly, Forum Master. Exactly.

 

For sure what in the coolant had nothing to do with misfire. The water pump load is negligible to the engine power. I only can guess that the leaked tank somehow wet other electrical sensors leading to rough rpm, and eventually dried up and gone the issue.

 

This was one of my first thoughts as well, and is still possible. But I poured a gallon of water all over the expansion tank area to rinse the old coolant off--the first time I replaced the tank, and the second time when I re-seated it--and it didn't happen again. This doesn't necessarily mean that the water invalidates the possibility of an electrical problem, especially because the engine was fully up to temp when I did it, making it evaporate quickly instead of seeping into various places.

I've had the idle just slightly change on older cars--fuel injected but very early and without OBD--due to air being in the system, but never anything more than a second. This is the only car I've dealth with that's relatively new and has a mechanical fan/water pump. There's also the possibility that it was due to a temperature sensor that wasn't covered by coolant. The Volvo 240 I have has a known problem of a rough idle/no start due to the coolant temp sensor for the computer going bad.

 

There is no direct relationship between air in the cooling system and a misfire. None.

 

This is as good as jfoj.

It isn't helpful when doing a diagnostic on car--or anything else for that matter--to say "it isn't that" over and over again. A failed temp sensor can cause a misfire. That's a fact. Will it do it on an e46? I have no idea. Should air going past a water pump cause a rough idle and a misfire code? No. Is it possible? I don't know. Saying "it isn't that" doesn't help to clear anything up.

I mentioned all the other variables I could think of here, which jfoj--who I'm mentioning due to the most responses--ignored completely, and then mentioned as definite causes.

I can confidently say that 90% of the time I search forums instead of asking a question. When or if someone has a similar issue pop up, and the other variables don't point to a cause, it won't help them if the thread ends with "it isn't that."

If you and I were speaking in person, you wouldn't tell me "it isn't that." You would--probably; I don't know you--look at me skeptically and ask me if I checked the other likely possibilites. The problem here, and on most online forums and social media, is that I'm not in front of you, so the inclination is to rudely respond with "it isn't that" and end it there.

 

I've never seen anything like this, but the misfire was directly related to air in the cooling system, unless it was a coincidence happening multiple times in a row.

Not physically possible. It's something else. Get away from this train of thought. It's an entirely unreasonable conclusion.

JFOJ gave you a great possibility, but you ignored it. You have a single correlated data point. There is no way to logically connect "air in cooling system" to "engine misfire" unfortunately, even if they happened together. The engine detects misfires with the crank position sensor. Air vs water on the pump would not cause enough shock load on the belt to transmit through the belt, into the harmonic damper, and affect he crank enough for the engine to think it misfired.

Want to test your theory? Take off your lower radiator hose and let all the coolant out. Fill it all back up without bleeding it and run the car. It'll run fine.

 

I mentioned air around the water pump as one possible reason, and lack of coolant on a temp sensor as the other. The temp sensor seems slightly more reasonable to me, probably because I've seen it happen, albeit due to a failed sensor and not a lack of coolant.

The points--rudely, as I mentioned in my last post--made by JFOJ, clearly without his having read my posts, were mostly contradicted by my first post, with a few of them being made quite poorly, with regard to the claim that too much fuel is somehow a feature of the e46 and not fuel injected cars in general. To which I added the possibility of a battery on its way out as a similar cause under the same circumstances.

I have seen slight changes in idle caused by air in the system in two separate fuel injected cars with a mechanically driven water pump/fan, a Jeep and a Volvo. An empty cooling system and a properly bled cooling system should produce basically the same result, but air bubbles going past a water pump can cause a sudden shift in the belt speed. My thinking--which is very possibly misguided and totally incorrect, as a few people have mentioned--is that the sudden slight changes in idle due to this could be causing the engine to detect a misfire, and try to adjust the idle making it worse. If this is a stupid thought, it's a stupid thought. Being wrong and having been demonstrated a good reason that I was wrong is way better than walking away from something clueless.

Internet forums, for all the genuinely priceless good they do, are often cesspits of World of Warcraft level car nerds shouting out proclamations in hope of some kind of nonexistent crown. I was just trying to help someone with a vibration problem on the XI section and someone popped in and snapped at him for no reason at all. It happens all the time, and it's extremely irritating.

 

Is there really a purpose for this thread?? :banghead:

The OP wants to connect the misfire problem to the cooling system and in case that was outlined, there is really no correlation, however, there is some need to have some long and philosophical conversation on how if all the planets align properly the misfires could be directly related to the air in the cooling system.

I guess if this is what the OP wants to believe, then if the cooling system is properly bleed, the misfires will be gone and the car and owner will be happy.

Never mind the fact there were a lot of ancillary things going on like starting the engine and only running for a few seconds while moving the car or doing other things before shutting the engine off.

MY E46 will have misfires almost every time I move it a few car lengths to clear show around it or only move it in the driveway a few car lengths and do not allow the engine to run at least 3-4 minutes. This is a COMMON FEATURE of the E46, cold temps and a cold engine will aggravate the situation dramatically. People that live in warmer climates or start the engine and move the car only a few feet when the engine is warm may never experience this problem.

And BTW I have done nothing to my cooling system and it is not low on coolant.

Can we please stop the nonsense?

 

Best read of the day. Knowledge and patience v tunnel vision. Bravo.

 

When I went to drive the car into the garage from the driveway on the first day of the leak, the idle was a little rough.The next time I started it I got a misfire code and rough idle again. I finished everything, filled it with coolant, and started it. Rough idle. I could hear air in the system when I sat in the cabin, so I bled it again.

The rough idle went away, but I still got a misfire code. Bled it again, and still some air. The last time I bled it the code and rough idle went away completely.

I went back to read through this thread again, due to the cluster**** it turned into, to see if I left something out in my first post, or missed something.

There was no need for anyone to assume otherwise, without simply asking, but, again, the car started the rough idle/misfire the first time I started it after seeing the leak. The last time I started the car, prior to that, I had driven it 40 miles. Someone should have asked if this were the case before outright proclaiming that it probably wasn't.

I never left this out. Maybe I should've written in in all caps, with bold italics, but there was never any information pointing in a different direction.

None of the hubristic "advice" here was necessary considering the information that had been given.

And to swordsman, sorry for jumping down your throat with the ice cream melting comment when you only wrote a simple sentence about vacuum leaks.

 

I went back to read through this thread again, due to the cluster**** it turned into, to see if I left something out in my first post, or missed something.

There was no need for anyone to assume otherwise, without simply asking, but, again, the car started the rough idle/misfire the first time I started it after seeing the leak. The last time I started the car, prior to that, I had driven it 40 miles. Someone should have asked if this were the case before outright proclaiming that it probably wasn't.

I never left this out. Maybe I should've written in in all caps, with bold italics, but there was never any information pointing in a different direction.

None of the hubristic "advice" here was necessary considering the information that had been given.

And to swordsman, sorry for jumping down your throat with the ice cream melting comment when you only wrote a simple sentence about vacuum leaks.

You respond very strangely to people offering you help with your thread. They have given you information about very common things that happen with these cars and could very well be the source of your misfiring, especially given the sparseness of your original post.

Also "The job of the battery is to power every single electronic component in the car. The alternator charges the battery" is absolutely absurd. The battery does not power anything when the motor is running, the alternator runs at a higher voltage than the battery outputs and therefore has to power everything else. For the alternator to charge the battery it has to be at a higher voltage than the battery and the battery is incapable of discharging. The only way for the battery to be discharging while the motor is running is for the alternator to be failing.

 

lingon300k,

I'm in at this point because this thread should be locked. I am appalled at your behavior directed to myself and other veteran members here.

So you stated I was being a "dick", maybe you should look in the mirror!

If I am such an arrogant/dick or someone that offers "hubristic advice ", I would likely have been banned LONG ago from this forum. At least you claimed I am not stupid, how about just one step above stupid! You have no idea about my background and your not going to learn about it.

Funny how you are the one that seems to be cherry picking what answers or advice that you feel is correct and not looking at the bigger picture. I was not being a "dick", I clearly stated you were grasping at straws and chasing ghost. It was not until you decided to be a "dick" about what information you were receiving and what information you were willing to listen to that I called things out how I saw it.

It is quite clear from your statements about how you related the cooling system to the misfires and the fact that the vehicle engine and accessories run off the battery and alternator is only to charge the battery that you lack a very basic understanding of automotive systems and theory. Many people here are DIY'ers that have learned, listened, taken advice and have become rather proficient in either the E46 or vehicles in general, others are veteran mechanics that have earn a living repairing vehicles, may have been to trade school and may even be ASE Certified and you are arguing with this crowd, it does not make any sense, but it was your choice.

You think I behave any different in person then on a forum, not so much. I call things as I see them (see my comment above), call out people that are wrong and will actually SPEND the time and effort to educate people on the system or subject. You may think I am being condescending or hubristic in my approach, but I look at the BIG picture. I may be answering or countering a question or fact for a the person that started a thread, however, I also understand and realize there will be other people searching, reading and what I state and how I explain things is usually not just for an individual that started a thread but will hopefully help the greater majority of people that use a specific forum.

So anyway, good luck to you on resolving your misfire problem. I am confident you will be able to sort it out without my help, because your not going to get it.

I also think based on this thread there are a number of others that contributed then you basically spit in their face as well, they are not going to get their hand/tongue burned again by offering any help or advice to you.

Best of luck to you moving forward on resolving your own problems.

 

I had an expansion tank leak a few days ago, had to order a transmission thermostat, and was able to put everything back together yesterday.

When I went to drive the car into the garage from the driveway on the first day of the leak, the idle was a little rough. The next time I started it I got a misfire code and rough idle again. I finished everything, filled it with coolant, and started it. Rough idle. I could hear air in the system when I sat in the cabin, so I bled it again.

The rough idle went away, but I still got a misfire code. Bled it again, and still some air. The last time I bled it the code and rough idle went away completely.

Does this make any sense? Air affecting the water pump, in turn causing the pump to spin erratically, in turn causing a rough idle and an assumed misfire by the computer? Thermostat getting improper reading causing computer error causing misfire?

I've never seen anything like this, but the misfire was directly related to air in the cooling system, unless it was a coincidence happening multiple times in a row.

This is from your original post...you know, the very first one you made. BTW, the only way you could have a change in idle speed due to air around the pump impeller would, by definition, have to be due to a mechanical issue

Figure out how to disconnect your battery while driving and take a 15 minute video of you continuing on down the road with it disconnected. Or just google what happens when you remove the battery. The battery powers the car, the alternator charges the battery. The circuit is designed that way. This doesn't even get into the damage that can occur from bypassing the battery. Don't focus on buts and ifs and coulds just so you can be thread king.

This is from your last one. If you think it's any great chore to disconnect a battery from a car that's been started(I don't know, maybe just turn it on, leave it in neutral, and disconnect the battery..), maybe your car isn't the only thing that has had a misfire.