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Discussion Starter #21 (Edited)
Swapped in the spare DME today and It definitely seems to behave differently at idle. It's still a little rough but INPA shows pretty much random peaks in the 'run unrest' screen with what looks like slightly higher on bank 2, which also has higher LTFT (~17% vs ~9% on bank 1). Thinking there could be some issue with the DME then but likely also a vacuum or exhaust leak of some sort. With the original DME there are clear peaks on cylinders 4 and 3.

Also noticed some oil leaking from the sump when I was under the car the other day - not enough to reach the ground but the bottom of the sump is a bit wet. Possible that this could be admitting unmetered air? I'm reluctant to pressurise the system until I fix that though.

The spare DME is actually a US sourced DME so has the wrong software for my European car. I'm getting the same LTFT as with the original DME though and also an '01' code for the fuel pump relay. I've read that the US cars use a different relay so assuming that it's caused by the wrong software and not actually the relay.

I was thinking that I'd try reflowing the solder on the coil drivers of the original DME, and I still might, however I did a bit more hunting and ...

UPDATE:

Just noticed that the 'software number' in the bin file that I pulled from my DME (7837964) doesn't match the software number shown in INPA (7837956). Does the number from INPA mean anything or can it be wrong? Is it possible that I have mismatching software on my DME causing trouble?

Also I compared the bin that I pulled with BMWflash to the 7837964 0DA file and they're basically identical except that mine has 7400rpm rev limit and 299kph speed governor (and checksum of course). Suggests to me that someone has flashed a modified 7837964 software in the past possibly without updating the other software components.
 

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Have rough idle when warm, no codes, ICv changed and, no idle issues when AC is on. Car is RK stage 2 with evolve tune which is running rich (evolve need to fix the tune but their rolling road is shanked, or something). Took the car to a specialist in the north. . He said Vanos needs replacing based on Vanos software check .... hmmmm.... I didn’t believe him so I called another reputable specialist and he told me Vanos software checks often fail. The cars with, in my opinion, the most authoritative specialist in the UK. I’ll report what the outcome of his analysis / fixes are once I get the car back.
 

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Discussion Starter #23 (Edited)
Well mine is not the DME so I suspect a vacuum leak. I had a code for warmup misfire cyl 6 yesterday. Since the INPA run unrest shows highest peaks on cyl 3 and 4 (right after 5 and 6 in firing order) I'm guessing a leak in or around the cyl 6 throttle body or connector tube with cyl 5. Will smoke test it again at the weekend and hopefully do a better job than last time.

https://youtu.be/k04Y0Esbeag
 

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Discussion Starter #24
Smoke tested it today and there is smoke coming out from under the passenger side (bank 1) of the plenum.

Tomorrow I'll remove the plenum and test again, Actually thought I would need to block off the throttle bodies to smoke test without plenum but I guess not:

https://www.youtube.com/watch?v=KMJac8t8JXU

Hopefully it's as simple as that.
 

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Discussion Starter #25
Smoke tested with the plenum removed today. I saw no smoke coming from anywhere other than around the throttle butterflies. It seems to me that most smoke is coming from the cylinders with highest 'run unrest' values in INPA, i.e. 3, 4, 5, and 6.

Cleaned throttles 3 through 8 but ran out of cleaner. Didn't seem to reduce the amount of leakage either, possibly slightly out of sync? I guess a leak here would mean each cylinder getting a different amount of air particularly at idle which would explain the LTFT and rough idle?

Suspecting the leak that I observed when smoke testing with the plenum in place is doe to the throttle body to plenum seal but will test again with the smoke when I have time to see if removing and replacing the plenum helped.

I was only able to take a short drive so will reserve judgement until I've had more time to drive.

Smoke: https://youtu.be/8MGce0d4dNI
 

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Since you think the the leak is above the throttles or unmetered air unplug your MAFs again and the car should run normalish or better a least. It might still be trying to run on the old adaptions but it should be a bit better.
 

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Discussion Starter #27
I drove the car about 20km yesterday without the MAFs but it was the same. However I had reset the adaptations the night before and they didn't change during the drive so I wonder whether that may have affected things. When I later plugged the MAFs back in and drove a bit the LTFT came back up.

I would test more today but the car is booked for fixing the leaking sump. I'll get them to check out the leak too, figure it makes sense to fix the known leak before proceeding with anything else.

Videos of the latest smoke test: bit hard to tell exactly where it's coming from but I think it's plausible that it could be the plenum to throttle body flange.

https://youtu.be/vqI9zyH0OoQ
https://youtu.be/4GaSo_ssT_U
https://youtu.be/sUQFHJahP1Q
 

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That does not look like it is a plenum gasket leak, I guess it could be small and defined but that small a leak above the throttles would have little effect on the car. That size of leak below the throttles would have a significant effect. Could it be the way you are testing with the plenum off be missing parts of the engine?
 

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Discussion Starter #29
Well the car is back at the dealer because they are fixing the sump leak under warranty and I showed them the videos and they have looked at the plenum gasket and agreed to replace that for free as well.

Assuming that is the leak I think it makes sense to fix the leak I can see first. Will update when it's done, I'm not getting my hope up but finger crossed.

If it still idles like crap after that I'll take the plenum off again and put more smoke in it. It's possible that I didn't pump enough through the system to get to every point but I think I can rule out the #17 elbow because I injected the smoke into the ICV intake and #17 is just after that. FPR line is a different story though.
 

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My suspicion is the oring on the tube that is part of the ICV system that connects the throttles. I have seen a few leak there and it is hard to find.
 

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Discussion Starter #31
I guess replacing those will require re-syncing the throttle bodies?

If it's not better after the gasket as been replaced I'll test again with the smoke, Any idea what diameter (ID) the intake for the ICV is? I sealed it with duck tape last time but it leaked a bit. I would prefer to get a barbed joiner and seal it properly if I do it again. Forgot to measure when it was off unfortunately.
 

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Not really, but it is easier in the long run. Depends where the leak is. If it is the first or last you can loosen wiggle the tube out and bolt it back to the same location. I have never had a leak in the middle it has always been just one throttle to loosen.
 

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Discussion Starter #33
I got the car back from BMW a couple of days ago who replaced the plenum to throttle body gasket and fixed the leaking sump gasket. I had the impression that it's running a bit smoother but still showing too high values in INPA and the LTFT are still high and unbalanced.

So I smoke tested it again today, figured out a better method of sealing the intakes so they are 100% sealed. Anyway, the end result is a large leak coming from what looks like where the throttle body to plenum gasket fits around the cyl 1 throttle body. seriously, wtf, I'm starting to think the BMW dealer is pretty useless.

Anyway, besides that leak, I also was able to get more pressure in to the plenum this time and I'm also seeing a small leak from the front of bank 2. It's hard to tell where this one is coming from but It looks to be low down, doesn't look like it's coming from any of the hoses attached to the plenum or the valve cover gasket, any ideas?

I think I'm going to have to take the plenum off, block off the throttle bodies, and do this all again.

Bank 1 leak videos:
https://youtu.be/xTQzrkFrAJs
https://youtu.be/SXY7QrXllkg

Bank 2 leak video:
https://youtu.be/ZDa4YPD6IUk

Anyway, at least I feel like this probably is just due to vacuum leaks so it's just a matter of tracking them down and fixing them.

Thanks for all the help too Sailor, it's appreciated.
 

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Try using a mirror on a stick. That bank 2 one is puzzling seems lower that the throttles. The only thing down there would be oil return tubes from either the plenum or oil separators. Very hard to see in the video.
In fairness getting the gasket to seal on the throttles when they are new is a bit of a chore, the shape is not perfect and the clamp is also the wrong shape. A trick I learned after several failed attempts was to put a bit of petroleum jelly on both sides of the gasket where it meets the throttle and hose clamp. Theory was it would let them slip instead of bind. Since them I have always been successful. You are getting closer.
 

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Discussion Starter #35 (Edited)
Just a little update,

While smoke testing again trying to find the location of the bank 2 leak I leaned on the plenum and heard the hissing noise of the bank 1 (throttle body) leak change. After playing around a bit I figured out that I could stop the leak if I lifted slightly on the front of the bank 1 side of the plenum. After sticking a wooden wedge between the valve cover and plenum to keep it lifted I was able to temporarily 'fix' the leak.

After doing that I managed to figure out that the bank 2 leak was coming from the lower end of the plenum oil drain hose. Again there was a hissing when I pumped and wiggling this hose changed the noise. I tightened the hose clamp and no more leaks... in fact when I removed the plug that I'd used to block the bank 1 intake pipe there was a fair bit of pressure released which suggests to me that there were no more leaks.

Problem is, I went for a test drive with the leaks 'fixed' and there is still no change in behaviour. I will remove the plenum tomorrow and properly fix the throttle body gasket and smoke test again without the plenum - I found some plugs to block off the throttle bodies - but I'm now thinking that the vacuum leaks were not significant as you had suggested Sailor.

This leaves me thinking, what next? It would make sense to check the injectors but BMW should have cleaned them and replaced the o rings two years ago when doing other work on the car (I asked them to do it as 'PM'). It is possible that they didn't actually clean them but I would like to believe that they did what they said.

I still wonder whether the throttle bodies aren't properly in sync because of the varying amount of smoke that I got from each. Could this have that affect? Again, If I asked BMW to re-sync them I'm not sure I trust them to do it properly anymore. I would do it myself but I don't want to shell out 800eur on the tool for a 'maybe' so I would want to be pretty certain this was going to improve things.

To be honest, the car is driving well at the moment and it's a very light disturbance at idle so I'm inclined to just live with it for the moment, but it does bug me that it's not quite running as smoothly as it should.
 

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I am not going to say you don't need to use that tool to sync the throttles, but I have sync'd them with good results just using calipers measuring down to the plate from the rim. The procedure just seems so complicated. all you want is them to open all at the same time.
I doubt that it is injectors but I sure would not doubt it was injector orings. Here is the basic problem with a smoke test, the car runs on a vacuum and sometimes leaks don't form until you apply that vacuum. I am not a fan of smoke tests, I always seal them up and pressurize the system then try a vacuum pump, although I have little success with the latter because something always leaks.
 

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Discussion Starter #37
I guess I could try syncing them myself, worst case I just have to take it to the dealer/a garage to get it done properly afterwards.

I'd thought the same thing about the smoke test. What kind of vacuum pump do you use? I don't have one but I have considered getting one of those little hand operated vacuum pumps, I guess that would take some pumping to vacuum the whole system though. Are you just looking for whether the system can hold a steady vacuum or whether it drops, thus indicating a leak? Also, wouldn't air just get sucked in via the cylinders, either by valve overlap or past the rings?

One thing I haven't tried is the carb cleaner test. I figured that the idle is smooth enough that I wouldn't notice a difference in running but presumably the engine speed would temporarily change still. Might be worth running the car with the plenum off and spraying the injector area.
 

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Are you just looking for whether the system can hold a steady vacuum or whether it drops, thus indicating a leak? Also, wouldn't air just get sucked in via the cylinders, either by valve overlap or past the rings?
Generally I am looking at pressure, because vacuum is harder to hear and harder to attain. I explained this to you once before, seal up the intake tubes and seal up the exhaust pipe. Then you are testing the whole engine for leaks. If you can't hear it you just turn up the pressure a bit more, well until you break something,LOL.
Try not to do that. The vacuum pump would only be used if the pressure held. So then any vacuum pump would likely do, but the one I use is for vacuum bagging boat parts. Even if I had a big leak it would cover the volume no problem. If doing vacuum you have to deal with the evap system also which is a pain. The tank will hold pressure but the evap system wants to let outside air in when it is exposed to a vacuum as it would be when you purge the tank of vapor.
 

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Discussion Starter #39
Ok, I misunderstood because I missed that you said pressurize.

Today I removed the plenum again and I have tightened the gasket around the Cyl 1 throttle body. It was quite easy to turn the screw (worm drive?) on all of the hose clamps so now I'm wondering how tight they should be. I would typically tighten these until they are 'snug' and this was far from that. Unfortunate that I won't know if it's stopped leaking until I get the plenum back on though :\

I also had a play with the throttles and noticed that the bank 2 butterflies would open about 1mm before the bank 1 butterflies moved. I'm thinking that this may explain the imbalance in the LTFT between the banks. I adjusted the pull rod for bank 2 so that they both start moving together, problably not a good idea to do this without the right measurement equipment but I figure at least if it changes the behaviour of the engine it might tell me something.

I also noticed that some of the butterflies on each bank will start moving fractionally sooner than others. I don't know whether this means anything but coincidentally the ones that start moving early are the ones that leak the most smoke and the ones with the highest 'run unrest' values in INPA.

Current theory: vacuum leak is causing high LTFT, bad throttle sync between banks is causing the imbalance. Guess I'll know more when I get it back together tomorrow. Fully prepared to find that the leak is fixed but makes zero difference to LTFT :)

Video showing bank 1 vs bank 2 throttle opening:
 

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Discussion Starter #40
Btw, Since I've got the plenum off again I figured I'd replace the '#17' elbow. Any tips for replacing this? It looks a little tight in there.
 
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