Timing

[monkeyboy]

Hi.

If, hypothetically, I was to replace both timing chains and loose track of the timing, how can I tell which cylinder should be firing for a particular TDC. I presume the injector only fires on the compressing side, so how do I tell which side I should set to be compression on a particular TDC, or am I being a complete and utter tool

Ta.

 

[warmshed]

The valves will be closed on the one that is firing at TDC

 

[monkeyboy]

The valves will be closed on the one that is firing at TDC

I've had both the heads off as well as the chains I can set the timing by 'picking' one side to set to compression on the TDC mark but I need to know if the injectors fire one side at a time, and then obviously set the compression to synchronize with the injector

 

[ahutcheon]

Sorry, can't help.

 

[Ian J Hartley]

Both injectors fire at the same time (monotronic) triggered by one hall sensor. then both plugs fire at the same time, triggered by the other hall sensor.

 

[monkeyboy]

Both injectors fire at the same time (monotronic) triggered by one hall sensor. then both plugs fire at the same time, triggered by the other hall sensor.

OK, thanks. Doesn't that chuck away 1/2 your fuel on the exhaust side?

I knew about the plugs as there is only one coil (R1150 single spark)

 

[Ian J Hartley]

Not on the exhaust side, as that's burnt. The unused slug of fuel hangs around in the inlet manifold, and is then charged with a second slug on the induction cycle which gets sucked in the cylinder, and burnt. The injectors are designed to provide the correct amount of fuel. The length of time they remain open depends on the motronic, but the point at which they open is controlled by the hall sensor.

 

[monkeyboy]

Not on the exhaust side, as that's burnt. The unused slug of fuel hangs around in the inlet manifold, and is then charged with a second slug on the induction cycle which gets sucked in the cylinder, and burnt. The injectors are designed to provide the correct amount of fuel. The length of time they remain open depends on the motronic, but the point at which they open is controlled by the hall sensor.

Ahhhhh. I should have thought about that - the inlet valves will obviously be closed on the exhaust stroke so it will just fire into the manifold. Thanks - that all makes sense and the answer to the original question is 'it doesn't matter' which is excellent.

thanks again

 

[duckspeed]

The valves will be closed on the one that is firing at TDC

And the other pair will be rocking between opening and closing

 

[MattW]

As Ian says, batch injection and a wasted spark. The Motronic has no idea which cylinder is which. In fact it thinks it's attached to a single cylinder engine (the name is shortened from Monotronic).

 

[Cook1e]

As Ian says, batch injection and a wasted spark. The Motronic has no idea which cylinder is which. In fact it thinks it's attached to a single cylinder engine (the name is shortened from Monotronic).

Thanks for that, I never knew... Googled the details and now I understand (as much as I need to) something I didn't yesterday.

 

[ahutcheon]

As Ian says, batch injection and a wasted spark. The Motronic has no idea which cylinder is which. In fact it thinks it's attached to a single cylinder engine (the name is shortened from Monotronic).

Yep, no cam sensor so no way for the Motronic to differentiate the cylinders. May be set up like a single, but that's not where the name comes from: there were Motronic injection systems on cars long before the GS.

 

[MattW]

Yep, no cam sensor so no way for the Motronic to differentiate the cylinders. May be set up like a single, but that's not where the name comes from: there were Motronic injection systems on cars long before the GS.

Ok, perhaps I oversimplified.

The name comes from the mono-Motronic being a single channel system. You're quite right in that it was used in cars etc (including early fuel injected BMWs) but they had to include a cam position sensor to allow the unit to either target single pots or pairs (using batching / wasted sparks).