June 22

2011 BMW 328i, Rough Running Engine



Mark: Hi, it's Mark from TLR. I'm here with Bernie Pawlik, Pawlik Automotive in Vancouver. We're talking cars. How are you doing Bernie? 

Bernie: Doing very well. 

Mark: So today's story. 2011 BMW 328i. What was the story on this BMW? 

Bernie: So it came to us and the engine was running rough. The check engine light was on and needed some repairs.

Mark: What diagnosis and testing did you proceed with?

Bernie: So from there, first step of course, is to hook our scan tool up.  See what stored trouble codes are in the system. Found a couple of lean condition codes and it was very evident the engine was quite rough. So next step, of course, pop the hood, do a visual inspection. See if we could see anything obvious that was causing it. Nothing was noticeable. So our next step, one of our piece of diagnostic equipment is a smoke machine. And what it does is, under very low pressure, I think about a half PSI, it'll generate half PSI pressure and it generates smoke. And also the smoke has a bit of a UV dye in it, which is kind of cool. You can use for tracing as well. But essentially we, we hooked that into the intake system and turn it on and it pumps smoke through the intake system. So if there's any vacuum leaks or any leaks of any sort, we can find them.

And lo and behold, we found a huge leak coming from where the PCV pipes connect into the intake manifold. Kind of buried low down in the engine. A little hard to see, but we were able to you know, get some flashlights in there and see it, and found the PCV connector was damaged and causing an enormous vacuum leak.

Mark: Okay. So that was a big jump. Like why wouldn't you have looked at other things that might cause rough running first? What led you to the smoke machine, that there might be a vacuum problem? Is that common with rough running? Like what led you there first? 

Bernie: It is especially with the code, this is where the trouble codes are useful. Now people think, oh yeah, just plug the computer and it'll tell me what's wrong with it. Well, no, it doesn't. It just says that there's a code that, that the vehicle can't adjust the fuel mixture. Essentially the interpretation is the engine's too lean. There's too much air getting in. For the amount of fuel that the injection system can deliver. So there's the problem. 

So this is where we have to use our brains and our experience and our other equipment to figure out what exactly it is. The computer does not tell you that it's this particular piece that would make our was a lot easier if it did.

But you know, just as a little aside story, I often thought it'd be great if they put a fuel injection pressure sensor because often fuel pumps will fail on vehicles. I thought, wouldn't it be great if they had that sensor that would tell you that the fuel pump had failed? Well, some vehicles actually have that because they actually regulate the fuel pressure in the vehicle.

Well, that's actually one of the common failure items on those particular, not a BMW, but other vehicles, the sensors actually fail on these vehicles and they cause more problems than the vehicles that don't have them. So I thought, well, it's interesting, you know how sometimes you can over monitor stuff.

Anyways, I kind of went off a bit there, but anyways, the smoke machine, once we determined it's it's a vacuum leak is probably too much air. Smoke machine's a great tool because we can verify right there is it because of too much air because there could be other things like maybe the mass air flow sensor is reading incorrectly, but if we can verify and visually see that there's no smoke coming out from anywhere, then we know there's no vacuum leak. So that's why the smoke machine is a great tool. 

Mark: And how often do you end up using a smoke machine for testing? 

Bernie: We use it quite often. I mean, I'd say like about out of a hundred diagnostics, maybe 20% of the time we'll use it. You know, if it's something with with a vacuum type of leak, we'll use it. It's also useful for exhaust systems. If we can't quite determine a leak or there's maybe a pinhole of some sort, we can pump the smoke through there. There's a number of things this thing's useful for. Especially EVAP system leaks. It can be like a very tiny little leak coming from somewhere. So very good for finding little minute leaks.

Mark: So what was involved in repairing this PCV hose connector? 

Bernie: So we have to remove the intake manifold and in our intention wasn't to take it entirely out of the vehicle because it was actually, if we could swing it out of the way we could take the screws off and unbolt it, that was our original intention.

However, the job ended up turning out to be a little more involved and I'll get into some pictures and we'll have a look.

2011 BMW 328i, Rough Running Engine
2011 BMW 328i, Rough Running Engine
2011 BMW 328i, Rough Running Engine
2011 BMW 328i, Rough Running Engine

So that is the intake manifold of the BMW off the car. So eventually we have to take it off because if you can see, this is where our PCV connector was, was, and you can see a lot of kind of roughness there. This manifold is made of plastic and it was melted here. Now, normally there's no heat around this area that would cause it to melt. But this particular part here has a heater in it for the PCV system and electric heater. And it basically it must've short-circuited and melted.

This is our melted PCV heater. You can see very large hole here. That's where our vacuum leak was. This part, is what bolts into the intake manifold, as you can see, it's very deformed and why it would have melted the manifold. And the PCV hose connects here as well as here. It's like a double PCV hose. So it sucks and this part and this heated section as well. So that hose was replaced also. 

This is what the new heater unit looks like. You can also see there's an electrical connector there. Everything is is in pretty good order on this piece. It gives you a better idea of what the piece looks like. 

And a close-up of our melted area. You know, we ordered the heater first because we figured that's what we needed. But as we looked further and struggled to get this thing out, we realized the manifold would definitely not have sealed with that a new piece in there. We would've had another vacuum leak. So the manifold had to be replaced as well.

Mark: Okay. Did you have to get a brand new manifold? 

Bernie: Oh, we're able to get a used one from an auto wrecker. I mean, this is a part that really doesn't fail, it's a good used part to buy. There's nothing mechanical inside. It's just a piece of molded plastic. And as long as this thing wasn't burnt or there wasn't anything cracked or broken because of course, in a wrecker, in an accident if a car got hit hard enough and you know, a plastic manifold, you get cracked, I've seen that happen, but as long as it's good and solid, it's as good as brand new, essentially.

Mark: What else did you have to replace or repair along with the manifold and the PCV? 

Bernie: Yeah. So we did the PCV pipe. I didn't show a picture of that, but basically it's a pipe that connects to the two sections in the manifold, loops around and connects up to the back of the engine to the rest of the crankcase breather system.

Also the electrical connector to the PCV heater is completely melted and disintegrated. So we have to acquire that. And the only place we could find that was from an auto wrecker. It wasn't available new from BMW. Sometimes they sell these things. You can buy the connector and then the little wiring bits inside and you put them together, but electrical connectors are a little dicey. A lot of them are highly specialized and only fit in one spot. And they're only built one way. So we managed to get a good use one from the auto wrecker and soldered, you know, put that in real nice. 

Mark: So remind us again, what does the PCV valve do. And then why would it need a heater?

Bernie: Good question on both. Okay. So first of all, the PCV, actually PCV stands for positive crankcase ventilation. So the V is not actually double because sometimes it is.  It's a positive crankcase ventilation valve. What it does is it basically takes the blow-by gases from the crankcase, when it internal combustion engine is running some of the explosion that happens in the pistols, it can't be contained fully by the piston rings. It'll blow past into the crankcase. And so those gases, which are highly noxious are the most horrific pollutants, the engine puts out.

 They basically capture it, instead of it going out into the environment it's captured in a closed system, goes through a pipe, goes back into the intake manifold, it's sucked in and re-burnt. Why they use a heater, I don't know. But some vehicles do have them. It may be just to prevent the oil vapours from condensing in a cold engine. That's what I'm kind of assuming is what it is. And I should do my homework before I do this podcast, but I didn't.  

Sometimes I don't dig as deep as maybe I should, but I go, it's there for a reason. I figured no car manufacturer ever puts anything on a car for no reason, because it all costs money to make. So they're all committed to doing it the cheapest way they can. So there's gotta be a reason, but I'd say it probably prevents the vapours from condensing as they get sucked into the intake manifold on a cold engine. 

Mark: And how did the car run after repair?

Bernie: Really good. Yeah. Ran fantastic. Like a brand new BMW, smooth and no check engine light. And it was nice to find this issue because you know, so often we do diagnostics on things where we can't see what it is. We have to kind of interpret things and go, okay, well I think that's what it is and give an estimate for a thousand dollars. And it works in the end, but it's like, it's always a little hairy. But this is nice when you can go, Hey, the smoke machine, there's the leak right there. There's the problem, you know, it's a hundred percent found and verified. So it was a nice repair story. 

Mark: And is this a common issue with BMW 328 series vehicles?

Bernie: Not that I know of know, we work in a lot of BMW. This is the first time we've ever seen this happen. It's common in a lot of other different BMWs. You know, the auto wrecker, when I brought the sample manifold out, the guy who pulled it out of the car, he goes, wow, this is weird. I've never seen this before. So to me, that's an interesting indication that it's not an entirely common occurrence, but it may happen from time to time.

Mark:  And how are these BMWs? The 300-320series, I guess, how are they for reliability? 

Bernie: Well, you know, they're okay. We do a lot of podcasts on them. You know, I just like to say, you know, if you own one of these cars, they're nice, but you'll do a lot of repairs over time. I think, as we said, this isn't the most common thing you'll come up with. But electric water pump failures are common. Oil leaks are common. So, you know they need good maintenance. That's kind of the key. A lot of people don't maintain them well. The factory maintenance schedule on BMWs in my opinion is really bad, that your oil change intervals are like 25,000 kilometres, which is way too long. You should be doing it at 12 or maybe even less.

You know, if you do it more frequently with good oil you're going to get a lot more life out of your engine for sure. If you're buying a used one and it's been dealer serviced, it may not be the best service that could have been done. I mean, at least it's been done, but it has been done more frequently, that'd be better.  

Mark: So there, if you've got a BMW in Vancouver and you want to maintain it, you want it running a little bit more trouble-free. You want it maintained so that you can go in and start it up. And it goes even in the cold winter and the rain. The guys to see are Pawlik Automotive. You can reach them to book your appointment 604-327-7112. Or you can book online pawlikautomotive.com. They'll check out what you think the problem is, or what's actually going on and be ready for when you show up to get your car fixed. So it's done right the first time. Of course, check out our YouTube channel Pawlik Auto Repair. There's hundreds of videos, all makes models and types of repairs on there. We've been doing this for nine years. And thank you so much for watching and listening. We really appreciate it. Thank you, Bernie. 

Bernie: Thank you, Mark. Thanks for watching.

About the author 

Bernie Pawlik

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