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BMW 3-Series (E90 E92) Forum
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cylinder 5 misfires, out of answers
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09-14-2012, 07:12 AM | #23 |
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I may have an idea. I thought I read on one of these posts that occasionally the dme records misfires on the wrong cylinder. How about removing the coil from cylinder 5 and take a look to see what happens while the engine is running to be sure cyl 5 is truly cyl 5 in the dme. If this is useless, sorry... Just a thought
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09-14-2012, 08:18 AM | #24 | |
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09-14-2012, 08:49 AM | #25 |
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oh well. used to work on my 3 cylinder snowmobiles... damn thing always fouled one plug and you had to figure it out the old fashioned way...
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09-14-2012, 09:14 AM | #26 |
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Maybe the firing pattern of cylinder 1 adversely affected the firing of cylinder 5. When we drop timing post-shift, the massive corrections seem to happen in 1 and 5 simultaneously.
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09-14-2012, 02:14 PM | #28 |
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That's exactly what I was thinking, too. Firing order is 1-5-3-6-2-4, so I figured maybe misfire in 1 was looking like 5 to the ECU? I dunno. Swapping parts and replacing the sooty injector from cyl 1 and all plugs, moving coils, etc, and the misfire persisted but then would never throw a code! The owner will bring it back sometime (been a couple weeks already) to have the carbon cleaned, and I told him that the VC gasket or whole VC might need to be done, too. I figure if there is a lot of liquid oil in individual intake ports, that points to some sort of PCV failure.
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09-20-2012, 03:24 PM | #29 |
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update
2aaf code, thermostat code popped up anyone think the 2aaf code could have something to do with it? dealer thinks its dme or valve springs dme i would have to purchase and hope it fixed the problem to get reimbursed for it valve springs id be talking $500 in labor to just check them out |
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09-20-2012, 03:35 PM | #30 |
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Anyone ever stick an oscilloscope on the coil primary to see charging current and voltage? Watching the voltage on the coil ground and charging current under load at speed may show a defective waveform, and probably condemn the DME at that point. That transistor is less than $5, and there was a thread on replacing it just a few weeks ago.
Broken valve springs typically show up as a high-RPM misfire/false low rev limit. Also a possibility, but yeah, the VC R/R starts at $500 at a dealer. How much do you like this car? As in: How much are you willing to spend to continue chasing this problem? Are you getting this done under an extended warranty?
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09-20-2012, 03:37 PM | #31 |
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was trying to get it covered under my third party warranty
at this point im about half tempted to trade it in and say F itsince i just got my car back with a $1000 bill and no fix |
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09-20-2012, 04:07 PM | #32 | |
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I would strongly recommend looking up that thread. I don't think I am allowed to put that link here, but here is a Google search: https://www.google.ro/search?q=pulli...ing+ledges+n54
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09-20-2012, 04:33 PM | #34 |
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The washer between the vibration damper hub and the crankshaft sprocket was also broken on DZ's engine. That might cause some funky issues, especially with cam timing, as would the worn bearing ledges and broken seal rings (rectangrings in Germenglish).
High RPM misfires are a little easier to pinpoint, esp with a stock-like tune. Something is failing in the coil driver or injector driver circuit. Unless there's a broken valve spring, I'd be inclined to say DME quite certainly.
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09-20-2012, 05:10 PM | #36 |
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09-20-2012, 08:56 PM | #37 |
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Ask the dealer to swap the ECU with another compatible car to see if the problem persists...I know they may be hesitant but better than throwing money in the dark.
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09-21-2012, 09:03 AM | #39 |
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I don't think you can move ECUs anymore, even with programming. But call and talk to RPM Motorsport in BC, Canada - they do ALL kinds of BMW coding and trickery that dealers and regular shops just don't have access/programmers to do. I used them to program a cluster from an E46 M3 into a 330i w/ S54 swap.
http://www.rpmmotorsport.net/ |
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09-21-2012, 09:57 AM | #40 |
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I had a thermostat/waterpump failure and it made my car run like it was in an odd "limp" mode. No SES light, just a soft code, but once it got warm it drove like it was running pig rich (which I believe it was to cool the pistons). That being said, I don't think that Thermostat code is your issue.
X...
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09-21-2012, 02:24 PM | #42 |
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Hmm, I can see why they would say that. Basically, Engine ECUs have a serial number that are VIN matched from the factory for traceability and regulatory reasons. That's not to say it can't be done, just that they're "not allowed" to do it. I don't know specifically about BMW systems, but when dealers need to change a fried ECU, their diagnostic software can VIN write and immobilize a "fresh" ECU to the car. The same can be done with the used ECU, but they're not supposed to. I would take up James's suggestion and try a third party shop, if the problem does come down to your ECU/DME.
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09-21-2012, 02:39 PM | #43 |
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Oh, btw I totally forgot that the DME is covered under the emissions warranty for 8 years or 80k miles. It's in your service and warranty manual. Honestly, wait it out to see if the issue gets progressively worse, so you have some lead before your start emptying your wallet.
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