[dirtbikedude]

Hi All,

I proactively replaced the first 4 spark plugs on my BMW M235i. Didn't have any misfires before but after replacing the first 4 it's not throwing errors but definitely feels like it's misfiring. I've rechecked the connectors, they're connected solidly. I can recheck torque, but would that cause misfiring?
If I let it run will it eventually tell me which plug is faulting? I'm wondering if I should backtrack and put the original plugs back in but it's been a hell of an elbow workout just getting those in.

Any advice would be appreciated.

[designatedposter]

if they're too loose, you'd have compression loss and yes that would result in misfire.

where'd you get the spark plugs? counterfeit plugs are out there on ebay and similar sites..

finally, the first 4 spark plugs should be minimal effort.. you simply take off the engine cover and the ignition coils and plugs are right there... so what do you mean by elbow workout?

[jb-slow]

Triple check the coil connectors, they will still latch even if they're not connected properly.

[atek]

Why did you only replace 4?

If you have 4 new plugs and 2 bad plugs, that variation in plug consistency and health can and will surface issues.

I'd double check your work on the first 4 and then go back and do the last 2. they arent that hard to reach. Remove the cowl with 6 bolts, the struct brace with 4 bolts and then pull off the insolation and you have all the room in the world.

[dirtbikedude]

Ok, so I backtracked and put the original plugs back in, still misfiring so I'm clearly installing something incorrectly as the originals were not misfiring initially. I was using an in/lbs torque wrench that only went to 200 in/lbs. Everywhere I'm reading it needs to be torqued to 23 nm so that would be (203 in/lbs) so I'm going to get a ft/lb wrench and torque them to spec since my current one doesn't quite get to that spec.

The other thing I'm wondering, so connectors look good and lock into place but when you push them down into place are you supposed to hear a click or anything? I push them down into the notches they're supposed to go into, but I don't know if they're supposed get pushed further down or something.

[dirtbikedude]

Originally Posted by jb-slow

Triple check the coil connectors, they will still latch even if they're not connected properly.

What do you mean by this? They're a triangle, I would assume there's only one way for them to go in and connect?

[atek]

Originally Posted by dirtbikedude

Ok, so I backtracked and put the original plugs back in, still misfiring so I'm clearly installing something incorrectly as the originals were not misfiring initially. I was using an in/lbs torque wrench that only went to 200 in/lbs. Everywhere I'm reading it needs to be torqued to 23 nm so that would be (203 in/lbs) so I'm going to get a ft/lb wrench and torque them to spec since my current one doesn't quite get to that spec.

The other thing I'm wondering, so connectors look good and lock into place but when you push them down into place are you supposed to hear a click or anything? I push them down into the notches they're supposed to go into, but I don't know if they're supposed get pushed further down or something.

Again, what brought you to wanting to replace the 4 spark plugs in the first place? Was it just mileage - preventative maintenance?

When you plug the harness in, yes it should click once fully seated. Then you lock down the latch, which also makes an audible 'click when latched down fully.

Did you gap the spark plugs? What kind of spark plugs are you using? Have you pulled the CEL to see what codes/cyl is misfiring as opposed to just blindly shooting in the dark?

[dirtbikedude]

Originally Posted by atek

Again, what brought you to wanting to replace the 4 spark plugs in the first place? Was it just mileage - preventative maintenance?

When you plug the harness in, yes it should click once fully seated. Then you lock down the latch, which also makes an audible 'click when latched down fully.

Did you gap the spark plugs? What kind of spark plugs are you using? Have you pulled the CEL to see what codes/cyl is misfiring as opposed to just blindly shooting in the dark?

Yeah, mileage for preventative maintenance. At 56k miles right now. I'll double check my connectors. For spark plugs I'm using these from FCP Euro
They're pre-gapped so haven't messed with gapping, which could be a cause?

I haven't gotten any misfire CEL codes yet, although I haven't left the car on super long but yes, I agree if it throws a code it would make this a hell of a lot easier. Maybe if I let it run awhile it'll throw a code for me.

[atek]

So knowing that you are at 56k miles, and this is probably the first time the plugs have been changed. You absolutely need to change all 6 at one time. Not doing so will only hurt your engine over time.

Yes, if it is occasionally misfiring it will take the engine running for a few minutes to set the CEL; unless it happens on start-up..

Give it a little gas while (maybe take it up to 2K - 3k rpms) and see how the revs climb, do you notice any hesitation? If so, at what point? How is the throttle response?

[dirtbikedude]

Originally Posted by atek

So knowing that you are at 56k miles, and this is probably the first time the plugs have been changed. You absolutely need to change all 6 at one time. Not doing so will only hurt your engine over time.

Yes, if it is occasionally misfiring it will take the engine running for a few minutes to set the CEL; unless it happens on start-up..

Give it a little gas while (maybe take it up to 2K - 3k rpms) and see how the revs climb, do you notice any hesitation? If so, at what point? How is the throttle response?

Thanks bro, appreciate you helping troubleshoot. Ok so I got a scanner and I was getting misfire on cylinder 2 and 3. I replaced the spark plugs on 2 & 3 and re-torqued to 23nm and reseated coil packs. Cleared the codes and then fired it up. Idle was MUCH smoother and felt normal. Let it idle run for a couple minutes, ran perfect it seemed, still no error codes or anything. I then drove it and around fairly low speed, still no hesitation. Then pushed it 2-3k RPM and then right at about that range it started to hesitate and went into limp mode. I ran the code and still saying cylinder 2 and 3 misfire. I'm not exactly sure wtf to do at this point. Maybe switch coil packs?

[atek]

Originally Posted by dirtbikedude

Thanks bro, appreciate you helping troubleshoot. Ok so I got a scanner and I was getting misfire on cylinder 2 and 3. I replaced the spark plugs on 2 & 3 and re-torqued to 23nm and reseated coil packs. Cleared the codes and then fired it up. Idle was MUCH smoother and felt normal. Let it idle run for a couple minutes, ran perfect it seemed, still no error codes or anything. I then drove it and around fairly low speed, still no hesitation. Then pushed it 2-3k RPM and then right at about that range it started to hesitate and went into limp mode. I ran the code and still saying cylinder 2 and 3 misfire. I'm not exactly sure wtf to do at this point. Maybe switch coil packs?

Ok now you're getting somewhere. Yea, try swapping 1 & 2 and 3 & 4 coilpacks around and see if the misfire follows. That will help point to either spark/ignition or something else. Once we know what happens then, we can move on to something else.

Quick question, when you pulled the old plugs out how did they look? Can you post pics of them?

[dirtbikedude]

Originally Posted by atek

Ok now you're getting somewhere. Yea, try swapping 1 & 2 and 3 & 4 coilpacks around and see if the misfire follows. That will help point to either spark/ignition or something else. Once we know what happens then, we can move on to something else.

Quick question, when you pulled the old plugs out how did they look? Can you post pics of them?

Ok, swapped coil packs and still misfire on 1 & 3. So coil packs don't seem to be the culprit. I'll post a pic here when I get home. I'm wondering now, should I try swapping the plugs in 1 & 3 with 2 & 4 and see if I get an error on 2 & 4 if they're bad plugs? or go back to originals?

[atek]

Originally Posted by dirtbikedude

Ok, swapped coil packs and still misfire on 1 & 3. So coil packs don't seem to be the culprit. I'll post a pic here when I get home. I'm wondering now, should I try swapping the plugs in 1 & 3 with 2 & 4 and see if I get an error on 2 & 4 if they're bad plugs? or go back to originals?

Correct me if I'm wrong, but previously you stated the issue was a misfire on 2 & 3? Now switching to 1 & 3 after swapping coil packs? That may point towards at least 1 bad coil pack if the coil pack from 2 went to 1 and now 1 is misfiring, right?