[bsmoov]

So I just picked up my 3rd e91 6MT and the engine was a little rough.

Brought it home and it was the crankshaft sensor error. I replaced that and everything was as smooth as butter and passed smog.

A few days later misfires in 3 cylinders, I replace those 3 coils and everything if fine for a few more days, but then the check engine light comes on intermittently and misfire happens, but when I pull over, shut the car off and turn it back on, it disappears and runs fine again.

Now I got misfires on all cylinders. I replace all plugs and coils with bosch from fcpeuro. Misfires are still present with new coils and plugs. All connectors are fully seated and all coils are pressed all the way in and plugs torqued to spec.

I cleaned my MAF, still same.

I checked my Eccentric Sensor and no oil or any debris, still same.

What else could it be? Vanos?

Anyone else experienced an issue like this? How did you resolve it?

[charlieb]

Codes?

[bsmoov]

Originally Posted by charlieb

Codes?

Just the usual misfire codes. The generic misfire codes for every cylinder now, 1 through 6.


This is a 328i by the way.

[charlieb]

I've yet to face a misfire issue on my '07 but I keep reading about if its not the coils and/or the plugs, its the injectors. Common issues is the spade connectors on the injector harness no longer make consistent contact with the male side.

Originally Posted by nsjames

my misifre was a terminal on the injector that did not grip the spade tightly.

Pull the injector harness and use a pick to bend the center of the female terminals together.
Look on the injector male side for witness marks that are lighter than the others. That's how I finally found mine.

The fact that you turn it off and then restart without issue would make me suspect injector(s).

[turbohugh]

Walnut blast ? You seem handy , remove the intake manifold and look at those gummy valves 😂😂

[bsmoov]

Originally Posted by turbohugh

Walnut blast ? You seem handy , remove the intake manifold and look at those gummy valves 😂😂

ummmm...you don't walnut blast a n52, it's non turbo.

[bsmoov]

Originally Posted by charlieb

I've yet to face a misfire issue on my '07 but I keep reading about if its not the coils and/or the plugs, its the injectors. Common issues is the spade connectors on the injector harness no longer make consistent contact with the male side.



The fact that you turn it off and then restart without issue would make me suspect injector(s).

Let me try that...you wouldn't have a pic of the spade connector would you?

[charlieb]

Here's an image for a harness being sold on ebay.
You can see how the connector clip can spread apart.

Would be nice to see what your fuel pressure is when this is occurring.

Apologies if this is no help.
Shot in the dark but maybe. Hope you get it sorted.

[bsmoov]

I'll take a look at mine this weekend. Thanks!

[speedfreeq]

I had an intermittent misfire on '08 N52, replaced coils, plugs, moved injectors around, replaced injectors, replaced VANOS sensor (bc code) - consistent P0206 code, occasional P1071 and P0171 codes...still don't know exactly what the issue was, but it was related to injector harness for #6 injector. My issue was finally resolved by replacing the injector/coil wiring harness (12517566555) with an eBay item.

[TheMidnightNarwhal]

Originally Posted by charlieb

I've yet to face a misfire issue on my '07 but I keep reading about if its not the coils and/or the plugs, its the injectors. Common issues is the spade connectors on the injector harness no longer make consistent contact with the male side.



The fact that you turn it off and then restart without issue would make me suspect injector(s).

Wouldn't that log a code? I ran my car with no injector connected part of the priming procedure and I had a code for each injector. I'm a 335 though but still.

[JuniorB]

What's your fuel pressure at? If this checks out, may be a DME issue, do you have a msv80?

[hassmaschine]

Originally Posted by TheMidnightNarwhal

Wouldn't that log a code? I ran my car with no injector connected part of the priming procedure and I had a code for each injector. I'm a 335 though but still.

Anything related to diagnosing the fuel system on an N54 is completely useless for an N52. DI vs port injected...

[TheMidnightNarwhal]

Originally Posted by hassmaschine

Anything related to diagnosing the fuel system on an N54 is completely useless for an N52. DI vs port injected...

Yeah but even if the car is PI the injectors are electric? There is a connector going to each?

So then would it throw a code as soon as the connector is loose and doesn't connect to it.

[hassmaschine]

Ok, but unless there is a squirrel chewing on your wires, that's never going to happen. You'd be looking for an exterminator, not forum advise..

[Phyrexia]

Originally Posted by hassmaschine

Ok, but unless there is a squirrel chewing on your wires, that's never going to happen. You'd be looking for an exterminator, not forum advise..

You joke, but I literally pulled handfuls of empty acorn shells out from underneath my engine cover when I replaced my coils at 65k mi. (Between a dead clutch by 62k and this, I assume my car had an...interesting life before I took ownership)

[Doesha]

injectors. that's the last thing you can check. I just pulled mine off on a 06 330i and they had alot of junk

[bsmoov]

Originally Posted by Doesha

injectors. that's the last thing you can check. I just pulled mine off on a 06 330i and they had alot of junk

Did you have symptoms like mine?

If you replace all the injectors including the rail and it fixed it?


I took the car apart again (prior to doing so i started the car and ran it for codes again, but as usual the car all of a sudden ran fine again and no codes were thrown, smh). Anyway, all of the connectors to the coils were tight and secured. All of the spark plugs are torqued to spec.

I tried to get the the injector harness connector, but the sun was going down and I didn't want to deal with it yet. Is there a way to check the harness connector without taking the fuel rail/injectors out?



***Also could a rusted ground bolt cause these issues I'm having? On the valve cover, there are two ground posts with nuts on it. The one closes to the radiator is good and clean, but the rear one towards the cylinder 6 is rusted and corroded. Would something like that cause a misfire on ALL cylinders???

[tsosby20]

Originally Posted by bsmoov

So I just picked up my 3rd e91 6MT and the engine was a little rough.

Brought it home and it was the crankshaft sensor error. I replaced that and everything was as smooth as butter and passed smog.

A few days later misfires in 3 cylinders, I replace those 3 coils and everything if fine for a few more days, but then the check engine light comes on intermittently and misfire happens, but when I pull over, shut the car off and turn it back on, it disappears and runs fine again.

Now I got misfires on all cylinders. I replace all plugs and coils with bosch from fcpeuro. Misfires are still present with new coils and plugs. All connectors are fully seated and all coils are pressed all the way in and plugs torqued to spec.

I cleaned my MAF, still same.

I checked my Eccentric Sensor and no oil or any debris, still same.

What else could it be? Vanos?

Anyone else experienced an issue like this? How did you resolve it?

It could even be bad gas

[TheMidnightNarwhal]

Originally Posted by hassmaschine

Ok, but unless there is a squirrel chewing on your wires, that's never going to happen. You'd be looking for an exterminator, not forum advise..

No but my point was that the other person said with the time the spade connectors get loose and don't make contact.

I am saying if that were the case wouldn't it throw a code for that individual injector like it did on my 335i?

[hassmaschine]

That's total nonsense. The same connectors have been used for years on basically every car ever made (Amp/Tyco junior timer and power timer pins). They don't "come loose". Not in an E90's current lifetime anyway...

[Doesha]

well no I cleaned my fuel injectors and still a missfire cylinder 6. I know my small disa needs to be changed but I did find a snapped alluminum bold towards the cylinder 6 on the fuel rail side. valve cover gasket time now. I'm once again going to out new spark plugs and coils on cylinder 5 and 6 just in case they were bad coils when I do the gasket.

so far cleaned and swapped vanos. cleaned maf. new coil and plug cleaned fuel injectors with cnc and swapped 6 to 1 5 to 2 and 3 and 4 around.

next will be valve cover gasket and I can look at the essentric sensor that time next w plugs 5 and 6 along with coils and go from there.

but still it could be disa's or pcv even though I saw no leaks and no cracks around any of the pcv hoses it could still be leaking causing a vacuum leak