I honestly have no idea what is going on, although I do have a theory.

I have a 2005 Mini S with 15%red. CAI, Catback, plugs. I have just ovr 103000 miles. Several weeks ago, I started my car up on a very very cold day and, for the first time, experienced the "cold start chatter". It has not gone away, even with a rise in temperature. I am handy with cars as is my dad, and we deduced, from all of our research that I have failed chain tensioner. Ok, so Mini says it is just "acoustic". Well I guess that is supposed to make me feel better... It is hard not to think more damage is being done.

My motor basically sounds like a diesel. I bought the parts to fix the failed tensioner, but am waiting for warmer temps to fix it.

Today, I was driving on the highway, in 6th gear at 65mph, I decided to pass the car in front of me. I have never expeirenced what happened next which is why I am asking for support here. As I accelerated (still in 6th), hard, my RPMs went to about 4000, but the acceleration was not as sharp and snappy as I'm used to. In fact, it was sluggish and sounded like my engine was backfiring. It did not seem like my clutch was slipping. I can't help but think that the combustion is somehow being affected by the failed tensioner, which if it is not keeping tension on the timing chain, would effect the timing of the pistons, combustion, etc.

So on my way home I conducted an experiement. No matter what gear, the harder I accelerate, the more it "backfires". But, gradual acceleration does not present any issue. What is going on here?

Also, I noticed this "backfire" after the tensioner went and i got the chatter.

Maybe I'm completely off... I am not sure. I am just hoping for some feedback from my fellow motorheads.


Thanks guys.

Cheers.

 

The tensioner failing might allow the blower to slip which would cause loss of power. Timing chain is different and once it slips, car won't run (well at least).

 

Try a couple of basic issues. Check the terminals on your coil pack and make sure they are not rusted and/or corroded. #3 terminal is notorious for that. They clean up easy with STP carb spray cleaner and a rag and/or a brass brush.

You say you have 103K miles. Have the plug wires been changed? If not, get a new set and see if that fixes the problem.

Keep us posted.

 

I changed the plugs around 80k, but will check terminal 3. As far as the blower slipping, that sounds like it may be a possibility. How does the timing chain tensioner interact with the blower?

 

Yes check ingnition bits and drive belt. Also clean your front wheel speed sensors.

Jeremy

 

The Gen 2 cars have the chain tensioner issue more often (what you read here) Your Gen 1 car I figured you heard the belt tensioner which would rattle a bit if it was bad. The timing tensioner has no relation to the blower. It was my misunderstanding.

Check the belt tension and see if that tensioner is doing its job.

 

If timing chain tensioner is broken chain may be off a tooth and cause the backfire because of improper timeing between the crank and cam set up. used to happen with older cars if you put the distributer in one tooth off. the sensor that reads the spark advance may be reading wrong because crankshaft is off a bit due to chain off of proper place.

 

To add, the tensioner is initially deployed with oil pressure (unless it is released when installed). There is startup noise until pressure pushes it out. After that, it should (in Gen 1 cars) stay deployed or for sure once oil pressure is up (a second or so) it should be fine. If it is off a tooth, my experience is that it will run like crap at all RPMs if it runs at all..

Rereading the first post, are you sure you have the correct oil in it? Thick oil will make the engine sound like crap until it heats and thins out. Mobil 1 0-30 or 5-30 are on the list...(do a search, that topic has been beaten to death and I don't want to start it up again.)

 

Well I live in Buffalo so I put 10w-40 in the winters. There is actually no chatter when I initially start, it begins once the motor has warmed up.

Martin, I think it may have something to do do with your explanation. My belt tensioner is ok...so that rules out a slipping blower.

 

A loose passenger side intercooler boot makes a bad bad sound (like rocks in a blender) and would loose power...