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.

[t_marat]

Can it be something to do with the DME? I mean in hot days area surronding the DME must be at least 60-70C hot. Is there any cooling for DME, like fan or something like that?

[genphreak]

Does your ICV make a buzzing noise when the ignition is on? (Open the hood and listen to it). If not- could be bad (most do). Does it open up if you remove from the car and apply say 3V?

If possible try applying more voltage (but no more than 12). Does it open and close without any trouble, ie scraping, jamming, etc.?

If you are in a cold locale, perhaps your car cannot maintain operating temperature very well when it is very cold. BMW would have fixes for that- ask at a dealer what they suggest for the car. They are usually very helpful. If too expensive, at least you know what the experts would do :) Nick

[genphreak]

Can it be something to do with the DME? I mean in hot days area surronding the DME must be at least 60-70C hot. Is there any cooling for DME, like fan or something like that?The whole ebox is cooled by a fan that draws air from the cabin (behind the dash) the air vents out the top of the eBox through a long gap in the lid. The fan is hard to get to and troubleshoot- You have to remove the whole ebox and I expect it is thermostatically controlled to make life harder. Perhaps you'd have to pull out the eBox and connect 12V to the fan to be sure. Or just wait for a hot day and try holding a bird's feather over the gap in the lid to check for air movement.... ;) Nick

[t_marat]

Does your ICV make a buzzing noise when the ignition is on? (Open the hood and listen to it). If not- could be bad (most do). Does it open up if you remove from the car and apply say 3V?

If possible try applying more voltage (but no more than 12). Does it open and close without any trouble, ie scraping, jamming, etc.?

If you are in a cold locale, perhaps your car cannot maintain operating temperature very well when it is very cold. BMW would have fixes for that- ask at a dealer what they suggest for the car. They are usually very helpful. If too expensive, at least you know what the experts would do :) Nick
It is very cold in the winter and very hot in the summer. The pic is from winter. Today it was something like +35C (95F).
Once I inserted a screwdriver through the gaps in the intake manifold and touched the ICV. I could not feel any vibration through the screwdriver. I did not check if it opens with voltage or not. Will take it out anyway once the other ICV arrives.

[genphreak]

It is very cold in the winter and very hot in the summer. The pic is from winter. Today it was something like +35C (95F).
Once I inserted a screwdriver through the gaps in the intake manifold and touched the ICV. I could not feel any vibration through the screwdriver. I did not check if it opens with voltage or not. Will take it out anyway once the other ICV arrives.Sounds like you might have some luck w a new ICV. Yes it is easy to check if it opens and closes on a bench with any old 3-12V DC power adapter. You might want to research the correct resistances for the temp sensors also, you really need to check this stuff.
It might be worth having BMW do it if you don't have the time, the place or the info.
Seems that the data for the 520 is a bit hard to come by in this part of the world. Perhaps you could get one of those BMW TIS CD sets off eBay- they describe the procedure and provide the exact data to test for your car- right down to the VIN code. They are all over eBay- hella cheap too :) Nick

[Ross]

Unless you really baby your car carbon probably isn't the issue.
If you determine carbon to be the culprit some water may help. Back in the old days of carbonators just running a small stream of water down the carb. while holding the revs. up a bit would clear it out pronto. Certainly the same could still be done,just be sure water is downstream of the airflow sensor.
The Italian tune up is not a good idea if your engine is detonating.
Check also for vaccuum leaks before replacing the IAC.
good luck!

[Russell]

Knock sensor failure? Bad gasoline?

[t_marat]

Knock sensor failure? Bad gasoline?
Knock sensor would cause pinging?

[BillionPa]

kind of, if the knock sensor doesnt detect it, the engine timing would stay advanced, and allow the pinging to continue.

15wt oil is too thick for your car, stay at a max of 10, 0W40 is good.

chevron makes a product called Techron that is similar to ventil sauber, but wont remove carbon deposits as fast, although using it twice per oil change, and FP60 at every tank will prevent any further carbon buildup.

try to get a hold of some Auto-RX, and run that for 2 cycles.

[t_marat]

Where exactly is that knock sensor located? Would like to make a quick resistance check.

[BillionPa]

not sure where, but there are 2 of them, and they look like #14

http://realoem.com/bmw/showparts.do?model=HB51&mospid=47370&btnr=11_1161&hg=11&fg=10

[t_marat]

Eeerr, what is the resistance value for the crankshaft sensor? Bentley says they it should be accessable after removing the top engine cover. It does not give any resistance value. And also on the diagram it seems like it is located in the lower part of the engine.

[kick7ca]

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?


Check all intake boots and rubbers for leaks.

[t_marat]

Well, I did the Italian tune up and the pinging is gone!!! Thanks everybody!

[KenB]

Glad it worked!:D :D