valvetronic Motors-Steppers Or? How to Test

[80stech]

Come and go misfires could be worn valve guides. There is probably a better chance of something showing up with a compression test vs leak down test. I have no idea what PassthroughD is but would be good to get BMW diagnostics working if you don't already.

[cfoss]

The thing is-it ran great before tearing it down. I has had virtually 0 run time since the tear down. So I don't see how that could be the issue.

Chay

[80stech]

Exactly, you changed the valve seals and maybe did something that knocked some carbon loose, maybe bent or distorted/changed something ?? With the new seals there is less oil in the guides for the valve stems. Assuming you have all the basics for spark/fuel covered off.

[andrewwynn]

This will come out of left field but just did a repair on a Ford 4.6 that had misfire on cylinder 1 almost every day but once in a while on cylinder five.

It was the crank position sensor.

I have only guesses why that presented only on two cylinders but when we took out the old one it was covered in goo, likely containing a tiny bit of wear metal like the concept of a magnetic oil drain plug.

We prob could have just cleaned it off and put back in but you have to revive the AC compressor to get to it on that truck so def replacing was the way to go

The working theory is that the metallic pull buildup changed the sensitivity of the sensor so that mfg tolerances in the reluctor ring eventually read as too soon or too late and the DME calls it a misfire.

I've not replaced one on a BMW yet but I've read tech sheets that describe using shims to get the spacing perfect, they are stupid sensitive.

When they fail it's immediately obvious but when they just read wrong you'll get oddball behavior like missing on one cylinder with no secondary symptoms to back it up.

[aureliusmax]

Originally Posted by cfoss

Thanks for the info. I may hit you up for more on that if I can't get this thig to work.

I try not to bore people with long winded stories about this project. It's my daughter's bmw. In canada, you have to import vehicles from one province to another-this requires an inspection. I'm trying to get the vehicle good enough to pass. It was running fine, but had the typical valve seal problem found on these engines.

I pulled the cradle, fixed the valve seals (Which were absolutely awful), and upon reassembly it has a misfire-then it went away, now it's back. Super weird. So I'm trying to locate a fault which is intemittent-always a fun job.

I'm just picking away at issues that could lead to misfire. What lead me to believe it was valvetonic related was that I tried one of the 'fixes' for the valvetronic system which is to leave the ignition on for 15 minutes then try again...Like magic the misfire was gone so I thought the issue is valvetronic related.

However, trying this approach again did not fix the misfire when it came back, so I thought I'd dig into it.


See, long story.

Anyway, some progress last night. I checked the intake and exhaust cam timing-they are 100% right on. I'm now reassembling the drivers side valve cover etc.

I'm also trying to get a copy of INPA working so I can get some insight into this system. I'm trying to find the BMW PassthroughD but its nowhere....very frustrating!

************************************Anyone have a copy they'd be willing to share??******************************************* *****


Thx,

Chay

You best bet is to meet me up in Abbotsford and can get everything looked at . I have a bunch of N62 spare parts too. Otherwise, just buy a complete lap-top system from ebay with all the BMW tools for under $1000 worth it if you plan to keep the car or have others.

[cfoss]

That's nice of you to offer.

I'm on the island and don't get out to Abby much. I'd have to trailer it over the ferry...not cheap.

I bought a K+dcan cable from amazon-I'll see if I can get that to work. It was only $50. It's supposed to be way easier than pass through because you don't need the additional bmwpassthrud software for it to work.

We'll see. I don't give up easy lol.

I had a crank sensor fail on a cummins swap I did....not fun to find. Thanks for the tip.

I now have the coils and plugs laid out on the engine-I'll check them as I roll the engine over to see how the coils/plugs are doing. I ground the plugs with a stripped wire so there is no stress on the ignition system, and I can see the sparks as it rolls.


Chay

[80stech]

It would be good if you had at least a cheap ignition tester where you can vary the gap to make sure the coils and secondary insulation are able to supply enough reserve voltage. You want to stress the ignition because it's easiest to fire plugs out of the engine. I'm assuming you switched plugs and coils and the miss didn't follow.

[cfoss]

Well, it's a pretty good day.

I finished reassembling the top of the engine today, and meticulously connected and routed everything.

I set both sets of motors to the full valve open position, then backed them off until tension plus a bit (2 Turns).

I also charged the battery to full.

I switched on the ignition and waited 30 seconds....to my surprise there were way more whirrs and clicks....I suspect the motors were doing the limit shecks. I had not heard this before. Then I cycled the ignition off, and back on for 30 seconds, then attempted a start.

The engine fired up and is very smooth at idle and 100% responsive to throttle input.

I have to put some last bits of coolant pipe together before I can run it for an extended period, but this is VERY GOOD!

I was also able to get the new K+Dcan tool to work with VIDA. Why do you have to fight, then everything comes together at once lol.


Hopefully that's the end of my misfire issues, but after all the trouble I've had I'm not quite ready to call it done yet. But the engine is runnig strong like it should once more.


Chay

[andrewwynn]

I believe the appropriate phrase is cautiously optimistic


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[cfoss]

Thanks to everyone who helped me out on this thread. The x5 continues to run well and a couple of days ago I passed the provincial inspection

It will be insured and then I’m going to drive it for a couple of weeks to give it the medium term rest, then assuming it passes I will hand it off to my daughter


Chay