MyE28.com

Hey,

I've watched several videos now from our boys across the pond. Their engines appear IMO to startup very quickly and clatter much more than the several TDs I've experience. Injector pump timing could play a role in this.

Does anyone know of the official BMW injector pump timing spec for the European 524td? Also, do you guys crank it up a bit more after that? The American timing spec could be less aggressive as that reduces NOx emissions.

Thanks!
Chris

I don't have the answer to your question but have one of my own. I have been reading your threads and you seem pretty knowledgeable. I was always under the impression that diesel clatter was caused by the injector springs reaching their burst pressure. So why would timing affect noise?

Jay

The clatter of a diesel engine is caused by the combustion event. However, you're correct in that you might be able to hear the injectors.....they have more a subtle ticking sound.

With the old school deisel such as ours, when the combustion mixture reaches a certain temperature from compression, pretty much the whole thing ignites at the same time. It's a very violent combustion and that is why all internal parts of a diesel engine need to be heavy duty. Also, that is why the timing of the injector pump is important as the fuel ignites as soon as it's injected. The earlier it's injected the more noise it makes as the combustion is trying to force a piston down and the piston is more resistant to go down sooner rather than later.

A gasoline engine in comparison using a spark plug to create a flame front propagation that more gradually spreads through the combustion chamber.....hence no diesel noise. Also, that is why gasoline engine needs more advance of the spark event (ie 20 degrees BTDC) in comparison to our 5 or so degrees BTDC of our injector pump. However, if the combustion situation is not optimal, you can get spontaneous combustion called detonation that is very "diesel like" and not very good for the gasoline engine.

Late model diesels are much more quiet as they use what is called a pilot injection. It's a small amount of diesel that's injected ahead of the main injection event that calms down the diesel combustion overall.

Advancing the injection pump timing could produce more power, more mileage, easier starting, more complete combustion with less smoke, more noise, but at the possible expense of the integrity of the internal components. Peak cylinder pressures can rise very quickly if you aren't careful. I wanted to see what the European timing spec was and possibly advance my pump to that as I would think it should be safe coming from BMW.

Chris H.

PS. You sig is almost a deja vu....I did a double take! ;>)

If you ever find out about that timing spec, let me know. I am looking to pep my td up abit myself. Also, what type of mileage do you get? Lately I have been getting 26-29mpg, i fell it should be higher as I do most of my commute on the highway at about 70mph. Car has recently rebuilt injector pump and only trace of smoke is when cold or at WOT.

Thanks,
Jay

P.S. And as for the sig... great minds think alike.

The m21 is designed with a primitive sort of gradual fuel injection. Its nothing more than the design of the injector tip to open up a very small orifice initially to introduce soft combustion, while the orifice opens gradually more allowing the rest of the fuel to enter the swirl chamber and continue ignition. It might not be as sophisticated as the systems in some of the fancy common rail diesels of today, but its the same concept.

Also, what type of mileage do you get? Lately I have been getting 26-29mpg, i fell it should be higher as I do most of my commute on the highway at about 70mph. Car has recently rebuilt injector pump and only trace of smoke is when cold or at WOT.

When behaving myself, I get around 40mpg. My tweaks will be in this thread for more info:
http://www.mye28.com/viewtopic.php?t=29538

I also now run an electric fan instead of the mechanical clutch fan that I didn't mention there.

Chris H.

Did you ever find that timing spec?

Yes, I got this response from the Yahoo 524td group:
Re: European TD injector pump timing spec.?

Hi Chris,

i assume you are talking of my clattering intercooled td ? You are
right, I have advanced the timing to 0,81mm (timing belt already
10000km) to get more power and less particulate emission. Regular
setting of the german version is 0,72-0,76mm (0,74-0,78mm with a new
belt).
By the way, some european e28 td did have that electronic diesel
control, too, for example the Austrian version (which also had a LSD
with a taller gear ratio as standard). IP-timing is 0,63-0,67mm (belt
> 15000km, throw in 2mm using a new timing belt). Maybe that IP is the
same one found in your US-models.
Most of the other european versions of the e28 524td seemed to have
the straight mechanical IP, like that td I reimported from Italy last
year, which just differs in some standard equipment features.
E34 524td and e30 324td generally had EDC, IP-setting is 1,03-1,07mm.

Regards, Tom

Somebody doing their timing adjustment with the special tool will need to measure how many degrees difference this is from the American timing setting.
Chris H.

Tom Are you still in Escondido?

Looks like the last time he was active was 2008.