Hi fellow MINIacs and happy 2004 (my 1st post this year!).

Just thought I'd try to get some feedback from the collective knowledge pool on an issue that's been bugging me for a while but has gotten steadily worse:

I have fairly pronounced engine vibrations and resonance (distinct sound), on my Dec 02 build 03 MCS - stock engine - with now about 26.5k miles.
This has started some time ago. I did mention it at the last two dealer visits, but nothing was found.
When I first observed this, these vibrations occurred only occasionally and were not as pronounced.
Now they are there all the time:
They are there when starting the car. If the car is cold, they are in fact very strong. The car appears to idle rough and is noisy. Idling improves after warmup, and vibrations decrease slightly, but are still there. The vibrations are strongest at around 21-2200 rpm, and the car sounds like it has a modified racing exhaus instead of the stock unit it has, it is droning very loudly. This mellows a bit as rpms increase, but then reappears at around 3500 rpm. The virbrations are quite distinct, and can be felt through floor, pedals, wheel and even seats. If you don't know how the car feels, it may not be that apparent (and the dealer doesn't seem to think it is a problem, so far), but the vibrations were not there in the first 10k miles, and now are very distinct, and the sound of the car has markedly changed. The engine does not at all feel like the smooth engine my car once had, it feels more like a rough subaru boxer engine I remember from my outback, quite rough and 'uncivilized'. This became most prominent after the last track day, where I did lots of laps at sustained high rpms. That was only the second lap day though.

Almost exactly since the noise and vibrations have become permanent, my gas mileage has gone down significantly, e.g. for typical highway driving from around 30-32 mpg to 25-27 mpg, and for typical city from about 24-28 mpg to 18-22 mpg, a significant drop. This has coincided from summer to winter switch, but here in TX we have no winter gas formulation. Air temperatures are much lower, so if anything the intercooler should work better and the car have more power.

Some of you may remember the AC howling issue others have reported and I have had as well. It was never tracked down or resolved, and dispappeared because in winter time I stopped using the AC. However, if I now engage the AC the howling is gone. It may only appear in hot and humid weather, or it may have been supplanted by this permanent resonance and vibration problem. I do not think it is a minor problem, since even friends that used to drive in my car when it did not have this issue ask me what is wrong with the car.

Any thoughts anyone? A problem with catalytic converter? Ignition or timing problems?

Cheers,
M.

 

The first thing dealer is going to check is your DME software programming. Have you received update 36 already? If you haven't, that would be a place to start. other than that you could have a mechanical problem developing in the engine ranging anywhere from the sparkplugs, fuel injectors, engine wiring harness etc.

Since your car is still under warranty, your best bet is to take it back to the dealer and have them run a full diagnosis on it. You could also have a transmission related problem as well.

The problem with dealer technicians is that if the computer doesn't spit out a trouble code the automatically assume that nothing is really wrong with the vehicle. insist on them checking both the electronic and mechanical integrity of the different engine components.

Hope is nothing serious, but don't delay a day longer in having the dealer inspect the car. You have a warranty, use it.

 

I was also wondering what kind of mods do you have in your MCS? Pulley? Intake?

What kind of gas and octane rating are you currently using?

 

You say you now hear an exhaust drone? I'll bet there is something in the exhaust system. Perhaps a broken baffle somewhere.

 

Thanks for the feedback so far!
I agree, mostly the dealers will plug in the OBD tool, and if there is no fault code assume that nothing is wrong, but truly that doesn't mean that nothing is wrong.
I have software version 32, and have also thought about 36, but then am concerned that I might be buying more problems with 36 than solving. 36 is supposed to work well, but has not been tested that long. 32 AFAIK was the last version to work fairly well and without problems. Plus, the car ran fine for 12-14k miles on version 32..., but I will certainly discuss that with the dealer.

My engine is bone stock, no mods on the car other than a sway bar and the forge coolant tank. Yes, I will need to take it back in, but the drive is 1 hr, and the car has already spent a lot of time at the dealer for various problems. I was waiting until the problem would be so obvious that the dealer has to do something about it other than reading the trouble codes.
I still use the same gas, mostly Chevron 93 octane all along.
I agree with apexer that a good bet - other than the ECU software - may be the exhaust system, and I am concerned about the cat. On the track day I ran at high rpms, and have read that stock cats have a tendency to melt at very hi temps, hence the offer of racing cats. However, if that were the case, I would think that the engine management software woudl pick up on the change in backpressure or O2 readings from the sensor?

I will take it back in soon.
M.

 

MG,

I don't think exhaust would explain it (the vibrations.) Plug wires seated firmly? (Long story--different vehicle) I don't know if a bad or loose motor mount would cause vibes. Anything seriously wrong internally and I would think that there'd be other telltale signs.

Without more to go on it's kind of silly to speculate. I'd drop it off with the instructions not to call until they've fixed it. I learned (with another car) that accepting the "we can't reproduce the problem" line will get you nowhere.

Best of luck,

Jeff

 

Any updates? Did you ever get it fixed? What was the problem?

 

MG-BGT: I found your old post through a search; hope you're still reading this forum. I have had the same symptoms for about the last 10,000 miles, although I don't think my gas mileage has diminished (Aug. '03 build MCS - stock - now @41,000 mi). The dealer won't recognize it. I also noticed greater-than-normal engine vibrations at idle (sensed by placing a hand on the valve cover). I also have the oft-reported right-side clattering under acceleration (apparently a worn crank pulley vibration damper), which the dealer also won't recognize. Perhaps these are related issues. Otherwise, the car runs quite well. Did you ever find the cause and/or the cure? Has anyone else experienced these types of vibrations? Many thanks.