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Discussion Starter #1
I hope you guys can forgive me. I've been lurking here for several years but rarely post anything as I figure I don't have much in the way of knowledge to add.
I am, however hoping someone will be able to help me with getting my rough running LT straightened out.
It is an 2007 w/ 32000 miles on it. This started out as a stuttering/ stalling problem at low speed on hot days and a rougher than usual idle, so I decided it was time to give her a little attention. I replaced the plugs, fuel filter, air filter, checked valve lash, only one (far right intake on #4 was .005) was out of spec and that was able to be brought into spec by swapping the bucked from another valve that had a valve lash of .007 and this made them both .006. So should be good if but a little towards the tight side of acceptable. I also changed oil in motor, trans and final drive.
Put everything back together and she starts right up but still has the rough idle. The wife and I decide to take it in to town for dinner ( 28 mile round trip) and when we stop for gas I
notice the cap is hard to get off and when it finally does come off air rushes into the tank like no tomorrow. I left the cap loose for the rest of the trip but it still isn't running right.
When I got home I did the canisterectomy, short version, and this made no change except for the tank venting issue is now resolved.
After this, I took it out for another ride, this time without the wife, so I get on it pretty hard and notice a definite lack of power, no nice hit above 4000 rpm, and the top gear roll-on power seems way down and the bike has a real miss or stuttering problem when trying to just roll the throttle on from say 60 to 80 mph.
Back home we go and on another day I pull everything back apart and re-check my cam position-both lines on the end of the cams are perpendicular to the head when the #1 cylinder is @ TDC, so thats OK. No vacuum lines are off, intake boots seem to be all the way on and nothing looks like it is anyplace it could get pinched when reassembled.
Today, I pulled the hall-sensor cover off because there was oil around it and I thought maybe it had gotten oily and that was causing a malfunction, but it was dry under the cover.
Unless some of you have some suggestions for me to try, I'm about to take her to the dealer. My only real reluctance to do that is they are clear down in Detroit and it will be a real PIA to drop it off , and find a ride to and from there back home.
So, any one want to chime in on what I'm missing? Thanks, Matt
 

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Hi Matt, I'm not real an expert but I play around with that Bike since 2002.
Did you ever check synchronization, this is mostly the reason of unround, rough running Engine. Should check the balance of the vacuum lines and adjust of the same level if necessary.

Manfred
 

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Discussion Starter #3
No, I sure haven't checked that, I don't have a syncrometer, or slack tube, but I was thinking if I did end up at the dealers with it I would have them check that for me. I've wanted to buy one of those things for years and never have. Maybe now would be a good time.
Thanks for the reply, I appreciate it, Matt
 

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Matt,

Just prior to my fuel pump failure, my LT ran just like that. I actually rode it for about 3 days like that until it died completely.

It surprised me because I thought a fuel pump would either work or not work at all. The lack of power at higher RPM indicates a fuel delivery problem to me.

Ron
 

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If the problem is always there at medium and high RPM, I would look at fuel related components: dirty injectors, fuel pump, fuel pressure regulator. It is possible to check the last 2 items (pump and regulator) by installing a fuel pressure gauge with a "T" on each side of the fuel lines (pressure side goes to the most forward hose on the fuel rail of the injectors). The correct pressure reading is documented in the Clymer manual as 50 PSI.

If the problem is mainly at low RPM:
1) You have already eliminated the charcoal canister problems,

2) It would appear you have also eliminated many of the vacuum leaks issues, but some are more subtle, like the 4-into-1 rubber crankcase breather AND the O-ring under the intake manifolds (between manifolds and cylinder-head)

3) The last item I would check is the coolant temperature sensor. It is located and attached to the number 4 cylinder head (rearmost). There has been a few threads here during the last 12 months with similar symptoms solved with its replacement. Without the dealers computer or a GS-911 you can follow the wire (under the seat, left side) and check its value at the connector with an Ohmmeter.

At 70 F (21 C) the reading should be 2500 Ohms (+- 100)
At 86 F (30 C) the reading should be 1760 Ohms (+- 100)
At 220 F (105 C) the reading should be 187 Ohms

The last value above (220 F) is the temperature at which the ECU (Motronic) will start the radiator fans. The concept is that the resistance should diminish as the temperature of the engine increases - otherwise the ECU continues to feed the injectors a mixture that is too rich.
 

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May be a fuel volume issue. I've run into similar symptoms on other fuel injection systems where a restriction of some sort restricts intake into the pump. Its able to develop the necessary pressure to run but not the necessary volume to handle the higher throttle settings.

I'd pull the fuel pump and look for any kind of obstruction on the intake side. Make sure the strainer hasn't collapsed during the time the tank wasn't venting. While you have the pump out I'd test it by hooking some leads to the terminals and placing it in a bucket of fuel and observing the output (be sure to make the final connection at the battery used to power the pump, you don't want any sparks near the fuel). Look for a strong steady stream of output.
 

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Discussion Starter #8
I'd like to give all of you a big thanks. I never would have thought to look into the coolant temp
sensor, and I think I will check that even before the fuel delivery issue as I will need to get a
suitable gauge set-up to check the fuel pressure.
One more question though, If I check the fuel pressure with the engine running that should answer the question of adequate volume along with having enough pressure wouldn't it?
I'll post what ever I find just to pass along the info for whom ever else might find themselves
with similar symptoms..
Thanks again, Matt
 

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Discussion Starter #10
fuel pressure is 55 while running. Took it to the dealer today. Dumped in some fuel injector
cleaner and it seemed to get better on the way to the dealer
 

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I'm Surprised no one mentioned. You might have a pinched the vent line under the fuel tank, from the tank to the ex canister location. don't ask me how I i i know... :p
 

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Discussion Starter #12
Thanks, I actually unhooked the vent from the tank to the canister and re-routed it down through the same path as the battery vent tube runs so I know we're good on the tank vent thing. Right after I did the initial work on the bike that was a problem & I think the canister was filled with gas because I couldn't even blow into it.
Thanks to everybody who tried to help. I still have yet to hear from the dealer but after looking over the list of stuff we had already tried and me telling him it started to get better on the ride down after I dumped in some fuel injector cleaner, he seemed to think it was going to be nothing more than dirty/plugged injectors and maybe some wet gas.
I'll post what ever it turns out to be for whom ever else may be interested at some point.
Matt
 

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Discussion Starter #13
Well, it doesn't look like too many folks are following this, but here's what happened.
Took it to the dealers (BMW DETROIT) and Don, the service manager, rode the bike and when we talked the following week he said it ran just fin. We went down to pick it up today and I rode it home in 93 degree heat with no problems at all.

So, for anyone reading thru the "it runs like shit" posts, you might save yourself allot of drama by first dumping in about a half a bottle of fuel injector cleaner. It seems to have worked miracles for me.

I'd also like to say that even though I didn't require any actual service from them, BMW of Detroit did check out my bike, and were honest about the fact that it had nothing wrong with it and as always, were a pleasure to deal with, so thanks alot to them.
 

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Good news on the fix, Matt. Glad you got it resolved satisfactorily. And guess what - that's the second 'kudos' to the Detroit dealer just today!! Always glad to hear the good side of dealerships.

Ride safe, Matt. Best always.
 

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Matt, I have a '99 with 198k miles that is doing the same sort of things . I pulled the injectors out and soaked them in cleaner , helped a little , maybe i should dump some in the tank as well , what kind did you use ? I have thought that Sea-Foam is the best . but what you used seamed to work.
thanks
mark
 

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Discussion Starter #17
It was STP brand in the black bottle. And it was called "super concentrated fuel injector cleaner" and below that it says cleans plugged injectors, treats 21 gallons.
I also bought a bottle of sea-foam which I plan to add every tank or so,
Good luck and let us know if it worked
 
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