[tom.gnade]

Hi all,

I replaced my crankshaft position sensor last night and at least my car will start and run now, but every time I accelerate, I'm getting random misfires on all cylinders. The car is undrivable. It's right on the edge of limp mode every time I touch the accelerator - jerking, jumping, surging. I was getting terrible mileage and had smelly exhaust, and long-crank starts before I replaced the crankshaft position sensor. It seems to have fixed some of those issues - the old sensor was covered in oil, as was the electrical connector. I had high hopes that the crankshaft sensor was going to fix the problem, but unfortunately, I'm still at a loss for what is going on here. In the past 20k miles, I have replaced:

crankshaft position sensor
both camshaft position sensors
both vanos solenoids
sparkplugs
ignition coils
cleaned the mass airflow sensor
cleaned the air filter

I did add a 3 stage intake manifold, so my next step is to remove that and remove the Active Autowerke tune, to eliminate the DISA valves. I do wonder if I can just remove the tune and unplug the valves - will the engine run with the valves stuck in the open position if I do that? I wonder if that would be a good test of whether it is in fact the DISA valves or not.

Anyone have any good suggestions? I used non-oem parts for a few of these things, so I'm also contemplating biting the bullet and replacing each component with OEM stuff - I've been warned a few times now that it is a mistake to use anything else by my local BMW mechanic (EuroMotive). That would be a lot of extra money to respend without any clear cause, so I hesitate to do that (vanos solenoids and camshaft position sensors).

I am thinking maybe I should just replace all the ignition coils and spark plugs again - but I really do wish the computer in this car would just tell me what the hell is going on...

[E92William]

You could have both valves be completely bad and they still wouldn't cause these symptoms. The valves are open when the engine is turned off and closed when the engine is on at idle, then actuate open and close as per rpm changes so if you want to unplug them you can do so with the ignition on after turning on the engine and back off again to ensure they actuate to open. What are the current codes after clearing?

[tom.gnade]

Codes:
P0300 Random/Multiple Cylinder Misfire Detected
P0306 Cylinder 6 Misfire Detected
P0302 Cylinder 2 Misfire Detected
P0305 Cylinder 5 Misfire Detected
P0304 Cylinder 4 Misfire Detected

I suppose on the bright side at least cylinder 3 and 1 didn't misfire? I could go ahead and replace all the ignition coils and spark plugs again - but I'm confused why they would only last 20k miles.

[tom.gnade]

Not 100% clear on your instructions for the DISA valves:

1) turn engine on
2) unplug both valves
3) turn engine off

or

1) turn engine on
2) turn engine off
3) unplug both valves

thanks.

[E92William]

The latter since your valves could be slow so it's best for them to actuate to closed when the engine is turned off and then they open once you turn it off again. So when you unplug them with the engine off after that, they will be in the open position.

[tom.gnade]

Incidentally, is anyone interested in an extremely cheap 2013 e92 328i with a few mods? Asking for a friend.

[tom.gnade]

Situation upgrade: the car no longer starts again. I am just absolutely perplexed right now. Why in the world would it start just fine and then stop? What the **** is going on with this thing???

[E92William]

No crank? Tried to tap the starter? Isn't this car a sulev engine? If it is I would recommend taking it in to BMW as this surely has a warranty and would have most engine jobs repaired for free

[tom.gnade]

It cranks but won't fire up. Battery is 12.1 volts. I have it recharging now, will try it again later. It's a standard N52 motor, not SULEV. Definitely no warranty...

[tom.gnade]

Would it be safe to unplug the MAF and try to fire up the car?

[E92William]

Can't hurt. Doubt it's that. Any codes now

[tom.gnade]

No codes, all clear. MAF unplugged made no difference. Cranks, but no start. The battery charge did seem to make the starter crank a little bit harder. I suspect the fuel pump is no longer priming - I haven't heard it the last few times I put the key in the ignition - could a failing fuel pump cause misfires while driving?

You'd think the car, with a zillion sensors and run by a computer system, would give you some indication of why it won't even start.

[E92William]

There are no sensors in the fuel system on these cars I'm pretty sure and well most cars for that. I would test fuel pressure. Little nipple on the fuel rail you can use. Sure seems like it because if it was anything else you'd be getting a code for it. I'm not sure but I think the fuel pump can be activated on inpa to see

[tom.gnade]

I suppose it's probably time for me to get familiar with INPA or call a tow truck. Thanks for your help!

[F31B48]

Originally Posted by tom.gnade

I suppose it's probably time for me to get familiar with INPA or call a tow truck. Thanks for your help!

Sounds like a possible fuel pressure issue. E92william is correct, there are no fuel pressure sensors on the N52. The only way to test it is by connecting a gauge to the valve on the injector rail. It should be about 75 psi.

[tom.gnade]

Ok, I had the car towed up to a nearby shop my parents have used for many years. They checked the car out and replaced the spark plugs, and it runs perfectly now - in fact, it might run better now than the day I bought it with 25k on the odometer. I think the camshaft position sensor was definitely the culprit, but also the shop said the spark plugs were completely burned up. Considering I put them in no more than 20k miles ago, I was very surprised.

So, this is a data point for everyone - your spark plugs can cause cylinder misfires, and they can become progressively worse until the car will no longer start. I’m really surprised that the BMW specialist I took the car to had a look at the plugs and told me they looked ok. Let’s just say the local shop with the extremely experienced guys who work on all makes and models were able to quickly and easily fix the car without much guesswork involved. Lesson learned.

I have to say this car seems to eat plugs. The guy at the shop asked me if I run the car really hard - I don’t think I do, but I guess that’s subjective. Let’s just say if you run the car like it wants to run, then replace the plugs every 15k miles. That’s what I’m going to do from now on. I’m extremely glad it wasn’t something serious or weird, and I’m surprised it was the plugs - I easily could have replaced them myself, but I just didn’t suspect them at all, and my BMW shop guy literally told me they were fine! Anyhow, I’m just happy I was finally able to stomp on the gas and have the car act like it is supposed to - I can confirm that the camshaft position sensor seems to have made a huge improvement in the throttle response - which was always something I felt was a little mushy on this car for some reason...

Anyhow, hope this helps someone - replace your plugs every 15k miles!

[aphael]

Originally Posted by tom.gnade

Ok, I had the car towed up to a nearby shop my parents have used for many years. They checked the car out and replaced the spark plugs, and it runs perfectly now - in fact, it might run better now than the day I bought it with 25k on the odometer. I think the camshaft position sensor was definitely the culprit, but also the shop said the spark plugs were completely burned up. Considering I put them in no more than 20k miles ago, I was very surprised.

So, this is a data point for everyone - your spark plugs can cause cylinder misfires, and they can become progressively worse until the car will no longer start. I’m really surprised that the BMW specialist I took the car to had a look at the plugs and told me they looked ok. Let’s just say the local shop with the extremely experienced guys who work on all makes and models were able to quickly and easily fix the car without much guesswork involved. Lesson learned.

I have to say this car seems to eat plugs. The guy at the shop asked me if I run the car really hard - I don’t think I do, but I guess that’s subjective. Let’s just say if you run the car like it wants to run, then replace the plugs every 15k miles. That’s what I’m going to do from now on. I’m extremely glad it wasn’t something serious or weird, and I’m surprised it was the plugs - I easily could have replaced them myself, but I just didn’t suspect them at all, and my BMW shop guy literally told me they were fine! Anyhow, I’m just happy I was finally able to stomp on the gas and have the car act like it is supposed to - I can confirm that the camshaft position sensor seems to have made a huge improvement in the throttle response - which was always something I felt was a little mushy on this car for some reason...

Anyhow, hope this helps someone - replace your plugs every 15k miles!

It is 100% not normal to be replacing your plugs every 15k. The iridium plugs that come with our cars should easily last 60k if not more. There is something fouling them up and I am sure that you have another issue that is affecting the plugs.

There is also a chance that they were not gapped correctly in the beginning leading to premature failure.

[tom.gnade]

aphael I would agree, it seems very odd. I wonder if the various sensors I replaced were affecting the timing - it was definitely a problem - and caused premature failure on the plugs? No idea. It runs stronger than the day I bought it right now, so at least for now, I can run it for a bit to see what happens. Maybe I'll just check on the plugs when I change the oil, and just change them when the gap starts to increase or if they look fouled.