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Discussion Starter #1
I recently noticed some oil underneath my car, so i decided to change the gearbox seals. I thought it's not so difficult a job, so i went to my local BMW "specialist" (huge mistake). When they returned my car it was misfiring really bad, so i left it for them to check it out. Turned out - they misplaced the flywheel which resulted in crankshaft position sensor giving inaccurate readings to the DME and wrong ignition timings as a result. The problem is - when they put the flywheel properly, the misfires didn't stop, but are now localised to the first bank of cylinders (1-4). Everytime we unscrew the sparkplugs from the left side of the engine - they are all wet (the right side is fine). Checked all the plugs and coils - all are firing, just at the wrong time, as it seems. Worst part - there are no codes except for "Misfire during warmup Cyl#1-4" and "Misfire during warmup multiple cylinders". So "the specialists" have been trying to fix this for 3 weeks (!) already without results :( I know there is not enough info, but maybe somebody experienced something similar. Thanks in advance for suggestions!

p.s. Before the gearbox seals change, the car ran perfectly. Also checked the cylinder compression - it's fine all across.
 

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Just to clarify, bank 1 is on the right side of the engine looking from the driver's seat. Yet you are seeing the spark plugs wet on the left side bank?

And you aren't getting any "misfire with cylinder cutout" codes (C4/5/6/7), just the warm-up misfire codes? Could that be because you aren't running it long enough?
 

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Couple of suggestions (even though this stuff shouldn't have been disturbed by the tranny re and re):
- the plastic elbow that tees off the idle air hose just downstream of the IACV to go to the evap valve has been known to get very brittle and break which causes bank 1 misfires during warmup. The evap valve itself is at the back of the valley.
- a CMPS going bad will cause bank-specific misfires with no CMPS codes. The CMPS's are easily accessible with the tranny removed but it won't be one getting accidently disconnected because that would generate a specific CMPS code. One got damaged?

You could ask your shop if they have done a smoke test for vacuum leaks and a VANOS test.
 

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Discussion Starter #4
Just to clarify, bank 1 is on the right side of the engine looking from the driver's seat. Yet you are seeing the spark plugs wet on the left side bank?

And you aren't getting any "misfire with cylinder cutout" codes (C4/5/6/7), just the warm-up misfire codes? Could that be because you aren't running it long enough?
I'm talking about the bank that is on the passenger side in a LHD car. No "misfire with cylinder cutout" codes. The vibration is HUGE, it feels like the car will fall apart at any moment, so i doubt it'll get better with car warmed up...

Couple of suggestions (even though this stuff shouldn't have been disturbed by the tranny re and re):
- the plastic elbow that tees off the idle air hose just downstream of the IACV to go to the evap valve has been known to get very brittle and break which causes bank 1 misfires during warmup. The evap valve itself is at the back of the valley.
- a CMPS going bad will cause bank-specific misfires with no CMPS codes. The CMPS's are easily accessible with the tranny removed but it won't be one getting accidently disconnected because that would generate a specific CMPS code. One got damaged?

You could ask your shop if they have done a smoke test for vacuum leaks and a VANOS test.
The thing is - when they installed the flywheel wrong, when the misfires first appeared - they didn't know what it was, so they disassembled half of the engine to look for a problem. When they found out the flywheel was in the wrong position - they assembled the engine back together and i'm 100% sure they did it wrong. So all suggestions are welcome!

"- the plastic elbow that tees off the idle air hose just downstream of the IACV to go to the evap valve has been known to get very brittle and break which causes bank 1 misfires during warmup. The evap valve itself is at the back of the valley."
Can you please show it on a diagram or a photo if that's not too much trouble?

"- a CMPS going bad will cause bank-specific misfires with no CMPS codes. The CMPS's are easily accessible with the tranny removed but it won't be one getting accidently disconnected because that would generate a specific CMPS code. One got damaged? "
By CMPS do you mean crankshaft PS? If they damaged it - shouldn't there be misfires in all cylinders, not just 1-4?

"You could ask your shop if they have done a smoke test for vacuum leaks and a VANOS test."
They are properly dumb. I already asked them to test the VANOS but they didn't know how to do it grrrrrrr Can you please give me a link on how to do those two tests or elaborate on the subject, if you have time.
 

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Since the vibration is HUGE, it won't be either of the things I suggested.

What do you mean, they dismantled half the engine? Did they disturb the cam timing on bank 1?
 

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Discussion Starter #6
Since the vibration is HUGE, it won't be either of the things I suggested.

What do you mean, they dismantled half the engine? Did they disturb the cam timing on bank 1?
They told me - no, but i wasn't there, so who knows. They tell me it's not related to cams or vanos, but there is no way for me to tell, since there are no codes related to this. They blame the evolve tune that came with RK kit, because the car was standing with disconnected battery for some time - it sounds stupid but i contacted Evolve anyways and they confirmed that there is no way the tune can get corrupted because of the disconnected battery.

p.s. One more thing i forgot to mention - i didn't try to drive a car for obvious reasons, but when i try to rev the engine - it feels kinda normal, like the engine is not misfiring or misfiring very little. But at idle it feels like 4 of the cylinders just cut off and it starts vibrating like crazy...
 

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Just thinking this through because it's a strange one:

IF bank 2 is firing on time (and it sounds like it is at least firing better than B1 based on the the dry plugs you are seeing on that side), then I don't think it can be the flywheel location or the CKPS since a problem with those would affect both banks equally. The fact the engine runs better above idle also supports it's not flywheel or CKPS.

I'm going to assume B1 is sparking OK (a weak coil or plug will often fire in air but not in the cylinder, but I can't think of any way all 4 B1 plugs/coils would suddenly become weak like that).

The DME controls ignition timing so the only way the timing could be radically different between banks is the two knock sensors on B1 being damaged in a way the DME can't detect. (It would detect shorted or open wiring.) But I doubt the DME would retard ignition enough to cause such severe misfiring.

The DME also controls injection timing so it's hard to see why B1 timing would be out and B2 OK. The DME uses the exhaust CMPS on each bank to detect firing TDC for timing so I was wondering if the B1 exhaust cam timing was out or the CMPS was bad but I gotta think the DME would set a code if it saw a serious mis-match between the B1 and B2 TDC signals. Unless it hasn't run long enough?

The plugs are getting wet so you are getting some fuel. It's hard to see how B1 only could be so starved or so over-fuelled, it won't idle. It seems a stretch to say it's a bad O2 sensor or the additive adaptation for B1 driven high or low by the time running with the flywheel on wrong. I wouldn't have thought either of those would cause fuelling so bad it caused very high vibration.

Not much help, I know. I listed all this stuff in the hope others will chime in.

It would be a big help if your shop could get some DIS-type data from the idle. Injections times, ignition timing, VANOS cam timing, cylinder unrest data, knock sensor timing retard, adaptations, etc.

I bet the cause is simple (in hindsight).
 

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Discussion Starter #8
Just thinking this through because it's a strange one:

IF bank 2 is firing on time (and it sounds like it is at least firing better than B1 based on the the dry plugs you are seeing on that side), then I don't think it can be the flywheel location or the CKPS since a problem with those would affect both banks equally. The fact the engine runs better above idle also supports it's not flywheel or CKPS.

I'm going to assume B1 is sparking OK (a weak coil or plug will often fire in air but not in the cylinder, but I can't think of any way all 4 B1 plugs/coils would suddenly become weak like that).

The DME controls ignition timing so the only way the timing could be radically different between banks is the two knock sensors on B1 being damaged in a way the DME can't detect. (It would detect shorted or open wiring.) But I doubt the DME would retard ignition enough to cause such severe misfiring.

The DME also controls injection timing so it's hard to see why B1 timing would be out and B2 OK. The DME uses the exhaust CMPS on each bank to detect firing TDC for timing so I was wondering if the B1 exhaust cam timing was out or the CMPS was bad but I gotta think the DME would set a code if it saw a serious mis-match between the B1 and B2 TDC signals. Unless it hasn't run long enough?

The plugs are getting wet so you are getting some fuel. It's hard to see how B1 only could be so starved or so over-fuelled, it won't idle. It seems a stretch to say it's a bad O2 sensor or the additive adaptation for B1 driven high or low by the time running with the flywheel on wrong. I wouldn't have thought either of those would cause fuelling so bad it caused very high vibration.

Not much help, I know. I listed all this stuff in the hope others will chime in.

It would be a big help if your shop could get some DIS-type data from the idle. Injections times, ignition timing, VANOS cam timing, cylinder unrest data, knock sensor timing retard, adaptations, etc.

I bet the cause is simple (in hindsight).
"I bet the cause is simple (in hindsight)" I think you are correct :) After three weeks (!) of "thinking" they decided to open up a plenum and what do you know, cylinder 2 velocity stack was completely torn off from it's base. We are waiting for a replacement, but i'm pretty sure that it is the cause of horrible idle. Will post the results when we change it.
 

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Hard to see how they could screw that up so I wonder if a massive backfire from when the flywheel was in the wrong way did that? Maybe ask them to check the other trumpets for cracks?

And come to think of it, if it was a backfire, it may have split an IACV hose on the B1 side, because I don't see why a missing trumpet would cause such a bad misfire.
 

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Just thinking this through because it's a strange one:

IF bank 2 is firing on time (and it sounds like it is at least firing better than B1 based on the the dry plugs you are seeing on that side), then I don't think it can be the flywheel location or the CKPS since a problem with those would affect both banks equally. The fact the engine runs better above idle also supports it's not flywheel or CKPS.

I'm going to assume B1 is sparking OK (a weak coil or plug will often fire in air but not in the cylinder, but I can't think of any way all 4 B1 plugs/coils would suddenly become weak like that).

The DME controls ignition timing so the only way the timing could be radically different between banks is the two knock sensors on B1 being damaged in a way the DME can't detect. (It would detect shorted or open wiring.) But I doubt the DME would retard ignition enough to cause such severe misfiring.

The DME also controls injection timing so it's hard to see why B1 timing would be out and B2 OK. The DME uses the exhaust CMPS on each bank to detect firing TDC for timing so I was wondering if the B1 exhaust cam timing was out or the CMPS was bad but I gotta think the DME would set a code if it saw a serious mis-match between the B1 and B2 TDC signals. Unless it hasn't run long enough?

The plugs are getting wet so you are getting some fuel. It's hard to see how B1 only could be so starved or so over-fuelled, it won't idle. It seems a stretch to say it's a bad O2 sensor or the additive adaptation for B1 driven high or low by the time running with the flywheel on wrong. I wouldn't have thought either of those would cause fuelling so bad it caused very high vibration.

Not much help, I know. I listed all this stuff in the hope others will chime in.

It would be a big help if your shop could get some DIS-type data from the idle. Injections times, ignition timing, VANOS cam timing, cylinder unrest data, knock sensor timing retard, adaptations, etc.

I bet the cause is simple (in hindsight).
This kind of thinking out loud is incredibly helpful, and my phone doesn't have the thanks button...so thanks for this.
 

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Discussion Starter #11
Hard to see how they could screw that up so I wonder if a massive backfire from when the flywheel was in the wrong way did that? Maybe ask them to check the other trumpets for cracks?

And come to think of it, if it was a backfire, it may have split an IACV hose on the B1 side, because I don't see why a missing trumpet would cause such a bad misfire.
The funny thing is - while my car was diagnosed by "specialist", my order of short velocity stacks arrived in another shop. So i'll make sure it runs fine with stock ones and go to the other guys for shorties :) IACV hose visually looks fine, but no way to check it since they don't have smoke machine, which is the only way to test them for sure, as they said (maybe they are being stupid again?)
 

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Discussion Starter #13
Did they offer any explanation about why that trumpet broke off?
Nope. No idea. Since shorties are waiting for me, i decided not to buy new stock one, but asked them to glue the broken one together, just to test it at idle. They've been trying to do it for two days without results, so they called me just now and said - it can't be done since trumpets are made from some kind of "special" plastic which can not be glued together grrrrrrr Doubt the plastic is anything out of the ordinary, but those guys sure are "special", as in "special school" special...
 

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How can you mis align a flywheel? I didnt know that there was a special way to align a flywheel. I know there is a dowel, and it can only fit one way.
 

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Discussion Starter #15
How can you mis align a flywheel? I didnt know that there was a special way to align a flywheel. I know there is a dowel, and it can only fit one way.
Yes, you can. Numerous threads on this board about this, as it turned out...
 
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