Pinging mystery

• I only hear it with the windows open.
• I thought it was bad gas (Shell). Tried a tank of Sunoco. No change.
• I called Dinan (I've got their engine software). The tech said he hasn't heard of this problem and suggested octane booster.
• Put in a can and the pinging stopped.
• I passed on the dealer's suggestion: $300 to reinstall OEM software and diagnose.
• My friend at an indy shop ran a freebee code check (still with Dinan) using a dealer-quality tester: zero fault codes of any kind.
• Went through the boosted gas. Next tank: the ping is back.

• It's hard to believe it's bad gas. I've run Florida 93 octane with no issues since I've had the car, and California guys have no issue with 91.
• I've had the irratic idle some here complain about. Two or three times the engine has died at a stoplight.

dparm wrote

I'd temporarily remove the tune and see what that does. Can you easily do that?

Megabrode wrote

Lately I've had occasional pinging (pre-detonation, valve clatter, whatever). It's intermittent, on sudden acceleration, in 3rd or above, at 2500-3500 rpm, especially uphill. The sound is a quick or (uphill) an extended "zzzzt," the classic marbles in a can. Pinging can of course cause engine damage.

The history:

• I only hear it with the windows open.
• I thought it was bad gas (Shell). Tried a tank of Sunoco. No change.
• I called Dinan (I've got their engine software). The tech said he hasn't heard of this problem and suggested octane booster.
• Put in a can and the pinging stopped.
• I passed on the dealer's suggestion: $300 to reinstall OEM software and diagnose.
• My friend at an indy shop ran a freebee code check (still with Dinan) using a dealer-quality tester: zero fault codes of any kind.
• Went through the boosted gas. Next tank: the ping is back.

The only relevant M3post thread I could find is here, posts 42 and 49:

http://www.m3post.com/forums/showthread.php?t=603650&highlight=OzCraig&page=3

Two members (Aviato and OzCraig) fixed what seems like the same problem by replacing the low fuel pressure sensor. But they had related fault codes.

Other possibly relevant notes:

• It's hard to believe it's bad gas. I've run Florida 93 octane with no issues since I've had the car, and California guys have no issue with 91.
• I've had the irratic idle some here complain about. Two or three times the engine has died at a stoplight.

Given all that, what do you think may be the problem, and what's a possible fix? Should I just go ahead and replace the LFPS, even with zero fault codes?

Thanks for your thoughts,

Craig (AKA Megabrode)

kimiraikkonen wrote

Not sure if I was getting the same sound, but more of a mechanical tin sound (maybe more valve noise)...........no effect on performance and chalked it up to valve noise. But this noise was consistently there when I was using Shell gas (we are 91 octane here in CA unfortunately).

In any event, switched to Chevron while back and do not hear the noise anymore. Did try Shell again briefly and noticed the same noise. So could be noisy injectors which are getting a bit cleaned up when using Chevron with Techron?

ItsGary wrote

Can you post an audio clip?

M3 Number 86 wrote

Did you change your exhaust?

Megabrode wrote

M3 Number 86 wrote

Did you change your exhaust?

About 10 months ago. OEM mod only. This pinging started maybe six weeks ago. I also have a K&N filter. That was a year ago. With the Dinan stage 1 tune, that's all the mods.

M3 Number 86 wrote

Sounds dumb and simple but have you checked the muffler? From the inside you can't tell where the sound is coming fro I've found. Front back left right.

oolas3 wrote

How many miles on the spark plugs?

donadio91 wrote

I’ve had this same noise for over 50k miles, just chalked it up to my loud exhaust and engine chatter. Only at WOT and between 2500-3500 rpm

GYY95M3 wrote

I've also experienced this ping/rattle phenomenon which has been going on for 18 months now. Frankly, I'm totally fed up with it because no-one seems to be able to positively identify what is causing it let alone resolve it.

To background the issue, I bought the car new in 2013 and it has been run on 98 octane fuel available here in NZ for the entire time, apart from a few long trips around the country when only 95 octane was available on which it ran fine.

For the first 3 years and 47,000km the engine never made any such sound and performed, as it does now, faultlessly. Now it makes this lower engine rattling noise randomly at any speed/revs, usually when a bit of throttle is applied, although it has now decided do a little rattle after each upshift. I'm used to all the sounds the engine, injectors and transmission make, as well as the slight "bog" before the DCT changes itself down.

In short, the only issue with this car is the pinking/rattling noise from the engine. It has never been tracked, thrashed or smashed.

It is still under BMW Factory Warranty, so the authorised BMW dealer has variously, over the last 18 months, changed oil, plugs, fed it fuel conditioner and generally scratched their heads over it for the 4 months that it spent in their workshop. I think it has its own parking spot. Finally, after the BMW NZ technical manager et al had taken it for a drive (running up 700km on tests so far) they did a compression test and pronounced that it needed a carbon clean, which they did, and it made not the slightest difference to the engine pink/rattle, which they have deemed to be "normal operation".

Just done a 4000km trip and it's still just as bad, if not worse, than ever.

I think they're wrong, what do you think..?

m3peat wrote

I have an OEM straight thru Mod Exh. I bought it like that so don't know if it did it before. Also not really an aftermarket. I have sort of convinced myself it's exhaust shields rattling. I had a bmw master tech friend listen and he didn't think it was of anything of concern but.....I'm not 100% convinced.