. How ddo you manually change the ignition timing on a 2001 Land Rover discovery SE?

 

you don't. It is controlled by the ECU and it can only be accessed through testbook.

Why do you want to change your timing?

 

discoguy,

thanks for the response.

We've installed a hydroxy system to the vacuum air intake, and the engine has begun to adjust and the timing is now off, due to the difference in
firing with the hydrogen versus gasoline. Do you think the automatic timing adjustments that the computer regulates will adjust favourably to the change?

how does it automatically adjust timing?

is there anyone that can help us with this?

 

You asked for it....

An engine control unit (ECU) is an electronic control unit which controls various aspects of an internal combustion engine's operation. The simplest ECUs control only the quantity of fuel injected into each cylinder each engine cycle. More advanced ECUs found on most modern cars also control the ignition timing, variable valve timing (VVT), the level of boost maintained by the turbocharger (in turbocharged cars), and control other peripherals.



[/align]E11: An aftermarket ECU[/align][/align][/align]ECUs determine the quantity of fuel, ignition timing and other parameters by monitoring the engine through sensors. These can include, MAP sensor, throttle position sensor, air temperature sensor, oxygen sensor and many others. Often this is done using a control loop (such as a PID controller).
Before ECUs most engine parameters were fixed. The quantity of fuel per cylinder per engine cycle was determined by a carburetor or injector pump.

Control of fuel injection
For an engine with fuel injection, an ECU will determine the quantity of fuel to inject based on a number of parameters. If the throttle pedal is pressed further down, this will open the throttle body and allow more air to be pulled into the engine. The ECU will inject more fuel according to how much air is passing into the engine. If the engine has not warmed up yet, more fuel will be injected (causing the engine to run slightly 'rich' until the engine warms up).

Control of ignition timing
A spark ignition engine requires a spark to initiate combustion in the combustion chamber. An ECU can adjust the exact timing of the spark (called ignition timing) to provide better power and economy. If the ECU detects knock, a condition which is potentially destructive to engines, and "judges" it to be the result of the ignition timing being too early in the compression stroke, it will delay (retard) the timing of the spark to prevent this.
A second, more common source, cause, of knock/ping is operating the engine in too low of an RPM range for the "work" requirement of the moment. In this case the knock/ping results from the piston not being able to move downward as fast as the flame front is expanding.
But this latter mostly applies only to manual transmission equipped vehicles. The ECU controlling an automatic transmission would simply downshift the transmission were this the cause of knock/ping.

Programmable ECUs
A special category of ECUs are those which are programmable. These units do not have a fixed behavior, but can be reprogrammed by the user.
Programmable ECUs are required where significant aftermarket modifications have been made to a vehicle's engine. Examples include adding or changing of a turbocharger, adding or changing of an intercooler, changing of the exhaust system, and conversion to run on alternative fuel. As a consequence of these changes, the old ECU may not provide appropriate control for the new configuration. In these situations, a programmable ECU can be wired in. These can be programmed/mapped with a laptop connected using a serial or USB cable, while the engine is running.
The programmable ECU may control the amount of fuel to be injected into each cylinder. This varies depending on the engine's RPM and the position of the gas pedal (or the manifold air pressure). The engine tuner can adjust this by bringing up a spreadsheet-like page on the laptop where each cell represents an intersection between a specific RPM value and a gas pedal position (or the throttle position, as it is called). In this cell a number corresponding to the amount of fuel to be injected is entered.
By modifying these values while monitoring the exhausts using a wide band lambda probe to see if the engine runs rich or lean, the tuner can find the optimal amount of fuel to inject to the engine at every different combination of RPM and throttle position. This process is often carried out at a dynamometer, giving the tuner a controlled environment to work in.
Other parameters that are often mappable are:
[ul][*]Ignition: Defines when the spark plug should fire for a cylinder.[*]Rev limit: Defines the maximum RPM that the engine is allowed to rev to. After this fuel and/or ignition is cut.[*]Water temperature correction: Allows for additional fuel to be added when the engine is cold (choke).[*]Transient fueling: Tells the ECU to add a specific amount of fuel when throttle is applied.[*]Low fuel pressure modifier: Tells the ECU to increase the injector fire time to compensate for a loss of fuel pressure.[*]Closed loop lambda: Lets the ECU monitor a permanently installed lambda probe and modify the fueling to achieve stoichiometric (ideal) combustion. [/ul]
Some of the more advanced race ECUs include functionality such as [li

 

It is distrubutorless ignition, so the firing is controlled by the ECU. It reads the position of the cam, airflow, O2 ( I think) and knock sensors to set timing. I think people have converted to LPG and had to have the ECU adjusted for the different fuel. YOu have to send the ECU off to have it re-programmed, and if I find the site again, I'll post..

 

MAP sensor too ;-)

 

Didn't know Disco's used a MAP sensor.... Where is it?

 

dear friends,
thanks a lot for the info. in particular, S4Poor, what you wrote, shared, here:
<<Programmable ECUs
A special category of ECUs are those which are programmable. These units do not have a fixed behavior, but can be reprogrammed by the user.
Programmable ECUs are required where significant aftermarket modifications have been made to a vehicle's engine. Examples include adding or changing of a turbocharger, adding or changing of an intercooler, changing of the exhaust system, and conversion to run on alternative fuel. As a consequence of these changes, the old ECU may not provide appropriate control for the new configuration. In these situations, a programmable ECU can be wired in. These can be programmed/mapped with a laptop connected using a serial or USB cable, while the engine is running. >>

i would love to understand where i can get a programmable ECU to do exactly that -
to be able to advance the timing for this particular application. it is actually brown's gas we're using, and it has an implosive force, rather than explosive.
so the timing needs to be advanced quite a lot forward...
where can i go to get a land rover programmable ECU that will allow this conversion?

also, the option for ECU flashing seems promising, to go thropugh the OBD port in the ECU.
this is all super new to us, but we're young, we're brave, we're reverent, and we'd like to make this thing work.
your help on the next step, to finding the right solution here (we do have PC laptops)
is MUCH appreciated.

 

No idea. Hopefully I never have to find it (not cheap). I'd would be very surprised if it didn't have an IAT/MAP sensor.

Let me check my CD's when I get home, I'll find some pics of it.

 

http://www.powerchipgroup.com./inter...sp?pid=Lan0010


Give them a call and tell them what you are trying to do. If they can't help you, get back to me..

Good Luck