June 13

2000 BMW 323i Engine Misfire Repair

BMW, Podcast


Mark: Hi it's Mark Bossert, producer of the Pawlik Automotive Podcast and Video Series and we're here of course with Mr. Bernie Pawlik of Pawlik Automotive in Vancouver. Vancouver's best auto service experience and 20 time winners of the Best AutoRepair in Vancouver as voted by their customers and today we're talking cars. How you doing this morning Bernie?

Bernie: Doing very well.

Mark: So 2009 BMW ... 2000 sorry.

Bernie: 2000 yeah, it's an oldie.

Mark: Yeah, BMW 323I. Had an engine misfire. What was going on with this BMW?

Bernie: Yeah so the vehicle was brought to our shop. The engine was shaking, running rough, clearly a misfire condition was happening the check engine light was also on. So we proceeded to do some testing and diagnosis.

Mark: What testing and diagnosis did you do?

Bernie: Well so for a concern like this, first thing of course is to verify the client's concern by driving it, which we did. Second was to plug in a diagnostic scan tool and just retrieve stored trouble codes, see what data's available, see what information we can get. So that was the first step. Found several trouble codes stored, but most predominantly was a cylinder four misfire. Well there was actually two, cylinder four and cylinder one.

But when we can review data, and it'll say how often the misfire occurred and cylinder four was clearly I believe there's 74 or 70 occurrences, it's actually probably a lot more. But the data for cylinder four was much higher than cylinder one. Cylinder one may have misfired just because of number four, but clearly cylinder four had the issue.

So from there, we can narrow down our testing and there's a couple ways to, I mean, there's a few things that will cause a cylinder misfire, one could be bad compression, the other could be an ignition problem like the coil or spark plug, or it could be a fuel injector, or a massive vacuum leak. Those are some of the things that can cause a misfire.

But it's pretty obvious from years of experience, it's pretty obvious when you have an ignition misfire, you can feel the roughness and because the issue occurred suddenly, it's usually a good first place to start.

So from there, we have a really nice lab scope we can actually test the ignition firing pattern by just putting a probe on top of the ignition coils. Now this is a direct coil on plug ignition system, so it's a six cylinder engine and there's one coil per cylinder. So we can go and test each coil while the engine's running, and it was very clear looking at the scope pattern that the number four ignition coil was not firing properly at all, it was dead.

So basically found the problem right there. I mean the other way that we do it without this is we can take the coil out, we can swap it to another cylinder, clear the codes, see if the misfire now moves to the other cylinder, that's also an effective method to find the issue. In this case, it was verified right off the bat. So number four cylinder coil was dead.

Mark: So is misfiring a fairly common problem on BMWs?

Bernie: It is one of the more common issues that we repair on these vehicles, yeah. It is yeah.

Mark: And the ignition coil tested bad? What else and was there anything else contributing to this misfire?

Bernie: Well the other thing that we always test of course is once we verify the coil's bad, I mean, the coil fires the spark plug, so you know we didn't know the condition of the spark plugs. It wasn't like you know, I mean if we'd known they were replaced last week or a couple weeks ago and we'd done them ourselves, we probably wouldn't look any further. But because there was no history on spark plug replacement, the next thing to do is pull the coil out and do a visual inspection.

There's a big long coil boot, it's a rubber piece, I'll show a picture in a minute and then of course, inspect the spark plug. Pull the spark plug out, inspect that, and the spark plugs in this case were extremely badly worn. So I mean even if we changed the coil, firing on an old spark plug is probably not the best thing because the coil has to work a whole lot harder to fire, so.

Why don't we just get into some pictures? So there's our nice condition, 323I, still, 235,000 kilometres, still looking good, it's a nice car. Again, if you take care of your car, it'll keep looking good and keep running well. What do we got for the next picture?

2000 BMW 323i Engine Misfire Repair
2000 BMW 323i Engine Misfire Repair
2000 BMW 323i Engine Misfire Repair

So this is the coil boot. I actually didn't take a picture of the ignition coil for some reason, but the ignition coil sits up here. And this boot is, basically attaches. The spark plug sits down here. Now you can see this rubber, this is a soft rubber boot but with 235,000 kilometres and almost 20 years of life, the rubber's kind of hard and cracked, and it was breaking off. So this was another piece that we replaced while we did it.

This was kind of like the equivalent to a spark plug wire, but it's very short. But again, it's critical to have this sealing properly because with anything electrical, electricity always follows the path of least resistance. So for some reason a gap were to occur here, it might actually fire the spark down the side of the spark plug wall instead of down the insulator or against the spark plug tube instead of actually firing the cylinder. So pretty critical piece to replace.

And then finally, the spark plugs, and I apologize this is not the sharpest picture I've taken, but you can see even in a fuzzy image, this is the old spark plug, this is the new one. Besides looking a little grungy, I'll just go over a couple of pieces of spark plug. So this is the centre electrode that serves as positive terminal of the spark plugs, and you can see this one is flat and flush with the ceramic insulator. You can see this one here, the ceramic insulator even in a crappy photo has got cracks, and the electrode is really badly worn. It's not flat and flush to the edge, and these are the ground electrodes. These are kind of an interesting spark plug. They have four ground electrodes. A lot of spark plugs if you've ever seen them, this ground electrode kind of goes over top of this, and it fires the spark directly.

But these ones can fire in any direction to any of these four ground electrodes. But again if you can see these ground electrodes are really badly worn against the insulator, there's a huge gap. So there isn't a spark plug gap spec for this particular spark plug, but you can see visually just how badly worn this is. So it's kind of a miracle this thing was actually running as well as it did but also a testament to how long spark plugs last nowadays.

Mark: So how often are spark plugs scheduled to be replaced on this model of BMW?

Bernie: I didn't actually look up the spec, but I think it's somewhere around 160,000 kilometres. That's kind of a standard nowadays for spark plugs.

Mark: So and it looks like these were in right from new?

Bernie: I think so. They were actually BMW ... you know, they actually said BMW on the spark plug so that tells me they were original equipment spark plugs.

Mark: So that's a pretty long life.

Bernie: That's a very long life.

Mark: So BMWs have earned a reputation for needing a lot of expensive repairs. How's this generation of the 3 series?

Bernie: You know, these are pretty good cars. I mean, they do have their list of quirks and things, I can rattle off a few. I mean, among them you know, ignition coils are a failure item and the crank case vent valves are a failure item. There's a lot of cooling system issues with water pumps and plastic parts, thermostats, hoses, even radiators, plastic parts get brittle and there's some suspension bushings, control arm bushings. Those kind of things.

Other than that, it's a good reliable car. And you know I think with any car, if you know the things that are going to go wrong and these are fairly predictable, then you can decide, hey is this car going to be worth it? And if you're buying a used one, you know, have these items been fixed and repaired?

But generally I'd say these are less ... Even though they're complex for their age, they're actually less complex than a lot of newer ones and I'd say more reliable.

Mark: So there you go. If you're looking for service for your BMW in Vancouver, the guys to see are Pawlik Automotive. You can reach them at 604-327-7112 to book your appointment, or check out the website, pawlikautomotive.com, YouTube channel Pawlik Auto Repair, hundreds of videos on all makes and models of cars and types of repairs and maintenance and of course, thank you so much for listening to the podcast. We appreciate it. Thanks Bernie.

Bernie: Thanks Mark and thanks for watching.

About the author 

Bernie Pawlik

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