Pinging while hot

[t_marat]

My engine starts to ping when its really hot. It pings when I try to accelerate. If I press the pedal really hard, close to the max, then the pinging is virtually gone. No pinging with cold, or lower than operating temp engine.
Also my ICV does not hold idle well when the egine is hot (no problem when cold). If I engage clutch and switch to neutral from higher rev, the engine goes directly to 0. I have to keep the car in gear till the rev is about 1000, then to neutral. This way it does not stall. Bought another ICV, haven't received yet.
My thinking is that it must be because of the dead MAF (already bought one from Ebay.de, on its way). Can it be the culprit?

In case of the carbon build up, should the engine ping always, be it cold or hot?

[BillionPa]

the engine should NOT ping.... Period.

[mamilapon]

My engine starts to ping when its really hot. It pings when I try to accelerate. If I press the pedal really hard, close to the max, then the pinging is virtually gone. No pinging with cold, or lower than operating temp engine.
Also my ICV does not hold idle well when the egine is hot (no problem when cold). If I engage clutch and switch to neutral from higher rev, the engine goes directly to 0. I have to keep the car in gear till the rev is about 1000, then to neutral. This way it does not stall. Bought another ICV, haven't received yet.
My thinking is that it must be because of the dead MAF (already bought one from Ebay.de, on its way). Can it be the culprit?

In case of the carbon build up, should the engine ping always, be it cold or hot?

It is carbon build up, and it will ping only when the carbon particles have become so hot that they start glowing. This in turn causes the air/fuel mixture to ignite before the end of the compression stroke, this is called pre- ignition. I had the same experience on my 535i. Now I use an additive called flashlube everytime i fill up, it seems to work.

[BillionPa]

order some lubro-moly ventil sauber, and put a can plus 3oz of acetone with every 10 gallons of gas you fill up on.

in 5 tanks the carbon should be gone

also use a top tier gas, try to go for shell V-power, and if you have an option, without ethanol.

also, what kind of oil are you using, and how often is it changed?

[genphreak]

My engine starts to ping when its really hot. It pings when I try to accelerate. If I press the pedal really hard, close to the max, then the pinging is virtually gone. No pinging with cold, or lower than operating temp engine.
Also my ICV does not hold idle well when the egine is hot (no problem when cold). If I engage clutch and switch to neutral from higher rev, the engine goes directly to 0. I have to keep the car in gear till the rev is about 1000, then to neutral. This way it does not stall. Bought another ICV, haven't received yet.
My thinking is that it must be because of the dead MAF (already bought one from Ebay.de, on its way). Can it be the culprit?

In case of the carbon build up, should the engine ping always, be it cold or hot?

Does your temp gauge ever go past half way?

Have you tested your ICV?

Do you use (hi-octane) premium fuel? Often if the octane rating of the fuel ya running is too low you get pinging when u put your foot down a bit.
Nick

[t_marat]

Does your temp gauge ever go past half way?

Have you tested your ICV?

Do you use (hi-octane) premium fuel? Often if the octane rating of the fuel ya running is too low you get pinging when u put your foot down a bit.
Nick

The temp gauge NEVER, NEVER EVER goes past the half way. I only noticed once that it actually edged a little (very little) past that mark, the temp outside was +42C (107F). I also do not have the electric fan, the one on the condenser. And this actually makes me worry; maybe my temp gauge is showing wrong temp? As the engine is warmed up. it rises from the blue zone to the middle as it should, but it never goes beyond the middle. My coolant never boiled. Also, I put in a new radiator in winter.

How can I test my ICV? Its a 2-pin one and I could not find the resistance value for it. Bentley gives values only for 3-pin ICV, it is 20 (1-2 pins) and 40 (1-3 pins) ohms. I measured mine and it was about 10ohms.

I use 96 or 95 octane.

lubro-moly ventil sauber, a very scary name Any other good brand name cleaners? I might not be able to locate that one, we usually have only well known brands, like Chevron, Shell or Vavloline.
My oil is Mobil1 0W-40. Last changed in the end of February. Before that, 15W-30 Mobil. Since February I have driven only about 5000km (3100 miles).

[Morgenster]

My engine starts to ping when its really hot. It pings when I try to accelerate. If I press the pedal really hard, close to the max, then the pinging is virtually gone. No pinging with cold, or lower than operating temp engine.
Also my ICV does not hold idle well when the egine is hot (no problem when cold). If I engage clutch and switch to neutral from higher rev, the engine goes directly to 0. I have to keep the car in gear till the rev is about 1000, then to neutral. This way it does not stall. Bought another ICV, haven't received yet.
My thinking is that it must be because of the dead MAF (already bought one from Ebay.de, on its way). Can it be the culprit?

In case of the carbon build up, should the engine ping always, be it cold or hot?

What does the pinging sound like?
I once thought that that was wrong with my 316 but it turned out to be misfires and synchro's being on their way out.
The M50 in your car should never ping unless carbon buildup is really bad.

[KenB]

Try an ITalian Tune-up first. The owner's manual recommends this but uses different terminology.

Find a stretch of highway, run in third gear @4500-5000 rpm for 5 minutes, repeat as necessary.

I do this occaisionally to blow out carbon buildup when light pinging starts. It is a byproduct of combustion and is present to some degree no matter what you burn. I use only premium gas and Chevron fuel injector cleaner regulary and still get a small amount of pinging once in awhile.

Running at a high rpm fixes it for me. I would try it before you start throwing money at it.

[t_marat]

Synchros are something withing the gearbox, right? As far as I know they are only engaged when shifting into gear, right?
For example, the same sound usually occurs when a car tries to move uphill in a second gear with revs as low as 600-800.

[t_marat]

Try an ITalian Tune-up first. The owner's manual recommends this but uses different terminology.

Find a stretch of highway, run in third gear @4500-5000 rpm for 5 minutes, repeat as necessary.

I do this occaisionally to blow out carbon buildup when light pinging starts. It is a byproduct of combustion and is present to some degree no matter what you burn. I use only premium gas and Chevron fuel injector cleaner regulary and still get a small amount of pinging once in awhile.

Running at a high rpm fixes it for me. I would try it before you start throwing money at it.

Kind of scared at doing that. The car is now 14 years old. Afraid that the springs on valves may have become weak, so that in a prolonged running in high rev a vavle might hit a piston.