Pings a little

[mamilapon]

Hi all, going up a hill ten minutes ago i noticed my car pings a little. I use regular unleaded (91 octane) which should be ok for the car,but i can't understand why its pinging. Outside temp is 20C (Sydney). Any ideas?

[BigKriss]

maybe just try 95 ron fuel from now on?

[sKilled]

95 octane or higher - says so on a little sticker next to my fuel cap.

[Fred Tyler]

For whatever fuel you are using, timing is too advanced. Having said that I'm not sure right now how to correct it for your car. I would check your service book to check. Unless you are running a non-standard chip your shold be able to use regular fuel!

[mamilapon]

95 octane or higher - says so on a little sticker next to my fuel cap.

Mate, your car is different to mine; yours is powered by an M50 with a higher compression ratio than mine which is an M30. So you would need a higher octane rated fuel.BMW actually recomends a minimum octane rating of 91 for mine. I'm just puzzled as to why it was pingging.

[mamilapon]

For whatever fuel you are using, timing is too advanced. Having said that I'm not sure right now how to correct it for your car. I would check your service book to check. Unless you are running a non-standard chip your shold be able to use regular fuel!

Its all stock and the timing is automatically adjusted depending on engine load.

[mamilapon]

I have no problem switching to premium or optimax (98), but i still want to know why is it playing up on factory recomended octane rating.

[sKilled]

Hmm, sorry. My mums car had a similar problem, and after accidentally filling it with leaded (ahhh yes those ays where we didn't know that everything we used or ate would have killed us) the pinging dissapeared for about 25k km. There is an additive one can buy from selleys I think it is that simulates the lubrication of lead for older vehicles. Perhaps this could help - can't hurt (and if it does, the guarantee on the bottle makes the manufacturer pay for repairs!). I would first try a higher octane though (cheaper and risk free), and then the fuel additives. Having said that, I will ask some of my gearhead mates as they might know of something I don't.

[joshua43214]

Possible carbon build up on the piston tops. The theory is, carbon buid up raises compression slightly and creates hot spots inside the combustion chamber. these hot spots will cause the fuel to ignite prematurely causeing ping. Useing a concentrated flush will clean the junk out and hopefuly eliminate ping.

One method that seems to work well is to use a intake/carb cleaner that has a straw. loosen the clamp on the intake bellows on the downstream side of the AFM and insert the straw between the bellows and the AFM. I don't recomend allowing the cleaner to pass through the AFM. hold the idle up to about 2k and spray it in. Don't let it stall under any circumstances, keep feathering the throttle and spraying it in. Dump the whole can in, and maybe a second as well. You will see all the crap come out the tail pipe, and it will stink like hell.

I like to spray it in in shots with idle held up a bit to cause the engine to huff a bit. then spray it in non stop with throttle at WOT for a bit. Then ack to shots. There are several products available made for doing this, but Ive never used the non professional versions so I can't speak for their effectiveness, The professional versions do incredible things for an old car though. Ive used them before doing top end jobs on cars to test them. the intake valves and piston tops come out looking like new, and the really good products even clean the exhaust valves.

[t_marat]

Any brand you would recommend?