help (rear end and smokey exhaust)?

1383 Views 11 Replies 6 Participants Last post by someday, May 2, 2005

someday

Discussion Starter · May 1, 2005 (Edited)

sooo...i'm trying to figure out if i'm freaking out because my car is still new to me or if it really may have a problem. i feel as though the car's rear-end shudders very slightly in 2500rpm rev range at light load. under hard acceleration i get the occasional wheel hop, but i'm talking about slow acceleration. does anyone else have experience with this? also, i feel my car runs too rich. anytime i floor the car, you see little clouds of smoke. when you start it, you can see smoke till it warms up. it's not blue, so i'm pretty sure if it's anything abnormal, it's just that i'm running rich. any knowledge and/or advice is greatly appreciated. oh yeah, the car is cpo'd through 2/11/08, but i just want to know what's up so i can explain it to the stealer.

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Kin Mak

· #2 · May 1, 2005 (Edited)

Re: rear end help?

someday said:
...but i just want to know what's up so i can explain it to the stealer.

That is nice of you to explain the problems to your car to the person that is trying to rob your car... :hihi:

- Kin

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someday

Discussion Starter · #3 · May 1, 2005

Re: rear end help?

in my past experiences with other dealers...it works out better if i can diagnose the problem i'm complaining about.

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e39m5nut

· #4 · May 1, 2005

Re: rear end help?

someday said:
in my past experiences with other dealers...it works out better if i can diagnose the problem i'm complaining about.

Yes I agree you get the best results when you can accurately describe the problem to the tech.

I see you live in Michigan. If you see white smoke from the tail pipes at a cold startup I'd say it is more likely condensation due to colder temperatures. If once the car is warm the white smoke goes away that's further proof of condensation being the cause and that's not a problem that's normal. What was the outside temperature when you saw the white smoke? If it's below 40 degrees then you should always see some white smoke from the exhaust because the hot exhaust mixed with cold moist air will condense producing the white smoke.

As for the black puffs of smoke under hard excelleration that's probably carbon being blown out of the exhaust which is also normal. After several hard excelleration runs you should notice less to no amount of black smoke coming from the exhaust. Carbon builds up in the motor as a result of the combustion process.

I think you're fine and what you are seeing is normal, however, it's always best to have it checked out to ensure nothing mechanical is the cause. For example, a leaky head gasket can cause white color exhaust to be present at all engine operating temperatures, regardless of the temperature outside.

--Mike

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e39m5nut

· #5 · May 1, 2005

someday said:
sooo...i'm trying to figure out if i'm freaking out because my car is still new to me or if it really may have a problem. i feel as though the car's rear-end shudders very slightly in 2500rpm rev range at light load. under hard acceleration i get the occasional wheel hop, but i'm talking about slow acceleration. does anyone else have experience with this? also, i feel my car runs too rich. anytime i floor the car, you see little clouds of smoke. when you start it, you can see smoke till it warms up. it's not blue, so i'm pretty sure if it's anything abnormal, it's just that i'm running rich. any knowledge and/or advice is greatly appreciated. oh yeah, the car is cpo'd through 2/11/08, but i just want to know what's up so i can explain it to the stealer.

I failed to put in my .02 in on your wheel hop cause. I've read that M5's can have trouble with what I believe to be broken rear sway bar mount(s)...that might be responsible for your wheel hop and shudder...a quick inspection of the rear suspension will answer that possibility. If that's not it, then I'd have the wheel balance checked...the vibration at certain certain speeds is usually a wheel balance issue, however, you're referring to engine speed and not a specific MPH range so wheel balance might not be it.

My car never experienced wheel hop so I suggest that you have the suspension inspected.

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someday

Discussion Starter · #6 · May 1, 2005

e39m5nut said:
I failed to put in my .02 in on your wheel hop cause. I've read that M5's can have trouble with what I believe to be broken rear sway bar mount(s)...that might be responsible for your wheel hop and shudder...a quick inspection of the rear suspension will answer that possibility. If that's not it, then I'd have the wheel balance checked...the vibration at certain certain speeds is usually a wheel balance issue, however, you're referring to engine speed and not a specific MPH range so wheel balance might not be it.

My car never experienced wheel hop so I suggest that you have the suspension inspected.

thanks for the advice. and yeah, i was referring to engine speed not MPH range.

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basil

· #7 · May 2, 2005

Regarding your low rpm shudder you might inspect the hard rubber piece that lies between the end of the transmission and the driveshaft, the drive shaft's middle bearing(I forgot the exact nomenclature of those two parts) and the velocity joint at the end of the driveshaft.

Good luck!

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BmwNut

· #8 · May 2, 2005

The shudder issue might be what basil was talking out, and I'll vote with him on it. The part is called a Guibo, or flex disk. I have been around plenty of BMW's that have had a failed guibo, but the experiance has varied car to car. An E36 with a severly worn guibo would vibrate the whole center console of the car at WOT. Another E36 with a worn guibo would only vibrate on starts and after gear changes. My mothers E34 would vibrate only after starts and then would go away quickly.
Have the dealership check it out, but that's what it sounds like from here. RE the white smoke, track it and see if it changes over time. Once the car warms up get out and smell it. If it has a fishy odor then you are burning coolant, but if it smells like normal exhaust then I think you should be in the clear. Unless someone put and aftermarket chip in it the car should have the mixture adjusted correctly. Good luck!
:cheers:

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ilundber

· #9 · May 2, 2005 (Edited)

I had a problem with wheel hops on my E34 M5. They changed the propeller shaft and the drive shaft on one side before they (BMW) figured out that the valve clearance was too small on some of the cylinders and that caused the "hopping". They adjusted the valves and it becames very smooth (for an M5

)

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someday

Discussion Starter · #10 · May 2, 2005

BmwNut said:
The shudder issue might be what basil was talking out, and I'll vote with him on it. The part is called a Guibo, or flex disk. I have been around plenty of BMW's that have had a failed guibo, but the experiance has varied car to car. An E36 with a severly worn guibo would vibrate the whole center console of the car at WOT. Another E36 with a worn guibo would only vibrate on starts and after gear changes. My mothers E34 would vibrate only after starts and then would go away quickly.
Have the dealership check it out, but that's what it sounds like from here. RE the white smoke, track it and see if it changes over time. Once the car warms up get out and smell it. If it has a fishy odor then you are burning coolant, but if it smells like normal exhaust then I think you should be in the clear. Unless someone put and aftermarket chip in it the car should have the mixture adjusted correctly. Good luck!
:cheers:

ding ding ding...good call guys. it was toast. the car is in right now while i enjoy my 325i loaner!

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BmwNut

· #11 · May 2, 2005

Good to hear that is getting taken care of. Let us know how you come out on the white smoke issue, but I dont think it will end up being that big of a deal.
:cheers:

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someday

Discussion Starter · #12 · May 2, 2005

BmwNut said:
Good to hear that is getting taken care of. Let us know how you come out on the white smoke issue, but I dont think it will end up being that big of a deal.
:cheers:

he said they just run rich. as long as it's normal i don't care.

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