Lately I've heard an intermittent rattle under WOT acceleration, it sounds like there is a marble rattling in the engine or exhaust. It has only happened twice and the first time I saw a plume of smoke come out after the sound happened. It is always very brief but the sound is very disconcerting. Has anybody experienced anything similar or know what the problem might be?

 

Sounds like detonation, pinging. Try a higher octane?
Does it happen at less than WOT?
I read somewhere that there is a detonation sensor, but dont know the details of how it works... varies timing I would guess.
Cheers,
Sam

 

Sounds like detonation, pinging. Try a higher octane?
Does it happen at less than WOT?
I read somewhere that there is a detonation sensor, but dont know the details of how it works... varies timing I would guess.
Cheers,
Sam

 

I have had this happen a few times....I'm sure its pinging. Bad tank of gas. With the winter blend of up to 10%ethanol its going to be hard to find good stuff. Maybe add octane booster? Not sure if its a good thing to put in with the ethanol in there? Anyone know?

 

I run a bit of Marvel Oil in the Alfa with 91 octane... but I can change the timing with a blunt stick when it pings. Detonation is deadly to the Alfa. I wouldnt think 'octane booster' would react badly with ethanol, but I'm not a chemist... and dont know whats in 'octane boost' anyway.... methanol? My limited understanding is that with higher compression you want a burn rather than a bang, which may (?) be actually enhanced with ethanol.
dunno.
Cheers,
Sam

 

Are you running with a Top Tier gas? If not, try it to see if you see any improvement. http://toptiergas.com/retailers.html

 

That's a bummer, hopefully it was just a bad tank. I always fill up with top tier gas (either Shell or Chevron every time) and always use the highest octane available, which around here is 91. I definitely don't want to add octane booster every time I fill up.

 

Update on the situation, I've been able to easily recreate it any time even after filling up with premium gas from another top tier station. It only happens under WOT at lower RPMs, for example, if I'm in 5th at 2k rpm and them floor it. Happens every time.

I'm making an appointment to have it checked out, I really hope that they can help me out but does anybody have any possible explanation in the meantime?

 

vac leak? Check the plugs, what color? Vac leak or over lean, or f'd timing. the plugs will tell you what mixture you have - lean or rich- so will give you a heads up on that. Check plugs after complete warm up, maybe off on the road for a bit.
... sorry, old italian stuff coming out.
Cheers,
S

 

Does it happen when you're stopped as well or just while moving? I had a rattle only when I was moving and gave it some gas. It sounded like there was a metal rattle in my driver-side door. I took it to the dealer for warranty work and it turns out it was the transmission control module hitting against it's own bracket. After the dealer service no more rattle.

 

This was definitely detonation, always while moving at low rpms in a high gear. Still haven't been able to get a hold of my dealer, which is a bit annoying.

 

i am having the exact same issue. took it to irvine mini, they couldn't reproduce it. went in myself, drove it with the tech - he insisted that all mini's do it... so i replaced the plugs myself (cylinder 1 had oil around the threads, but not that the tip - is that normal? none of the other cylinders did) and no improvement, so i'm taking it to crevier tomorrow to get a second opinion.

 

Apparently the issue with mine was the MAF sensor. It was being overly sensitive to minute changes in air density.

I wouldn't worry too much about oil around the threads, it could just be grease which I had on my old integra. I haven't checked the plugs on my mini yet. However it would be worth addressing the tech about since you only had it on one cylinder.

Don't let them tell you it's due to bad gas if you've been using premium. Ask them about the MAF sensor, apparently it's happened on more than one mini (obviously).

 

"Top Tier" gas is a marketing gimmick.

 

Problem is back, now dealer says it's a bad tank of gas although it has happened repeatedly in the last 2 months with gas from different stations. Keeping a running log of all events now.

 

Well, lugging will detonate. Shift at a higher rpm perhaps?
One thought to put in a cooler plug? If it was my car I'd put in a h2o injection system.
Cheers,
Sam