ECU upgrade... time wasted

[DanPromote]

Originally posted by MRsamdol@May 19 2006, 09:34 AM
Just wondering...

Remapping ecu with "piggyback" with no other modificatons or any type of forced air induction modifications?? Isn't that like just adjusting your throttle and timing only?? Sounds like a waste of the remap if you don't have any other mods..

Factory settings are often set to the safe level where air/fuel ratio are usually slighty rich and the ignition timing is retarded. With remapping/piggyback/standalone, they all have the same goal ie. to optimise your engine's performance. Depending on the ecu there are many parameters to set but the 2 main adjustments are the ignition timing and air/fuel ratio. By advancing the ignition timing and optimising air/fuel ratio alone you can notice approx 5% improvement even with stock engine setups.

Of course, it is always recommended that you finish all your hardware mods (eg. exhaust, air filter, turbo/supercharger, stroker kit) before doing the remap or adding a piggyback/standalone as they can only optimise your engine's performance based on the modifications or existing hardware that you have. If you don't have a turbo or nos for eg, don't expect your car to get a 100hp improvement by doing the remap or adding piggyback/standalone, it can only improve based your current setup.

Btw remapping and piggyback is not the same thing. Remapping uses your existing ecu and overides the current map with the new one much like a personal computer cpu bios flash (hence remapping) while piggyback is and add-on to your existing ecu. It may override certain functions and also have additional functions depending on its available functions.

 

[wglee]

Originally posted by ALBundy@May 19 2006, 12:23 PM
I think we should have a specific thread dedicated to the questions/viability of having piggyback ECUs and ECU re-programmed.

MrSamdol, bottom line is this, an ECU-reprogramming is more than what you have mentioned.

An ECU with Superchip, Hiop Chip, Dinan, Jim Conforti chip and etc will no doubt increase the vehicle's torque and hp output. This is achieved by altering the stock ECU's air fuel mixture mapping and also advancing the ignition timing. Now you have asked indirectly, why BMW didnt go the extra mile to extract these possible improvements in the engine performance?? The answer is, BMW manufactures cars for all over the world and the gas octane level varies depending on which country. IN Malaysia we have RON 92 and 97. In the states, they have Ron 87, 92 and 95 if I remember correctly. Some countries dont even have RON95 and so forth.

An ECU with an aftermarket chip requires the owner to use RON92 and above, anything less may cause pinging/knocking and probably wouldnt achieve the desired results. So BMW ECUs are made in such a way to ensure they can run on low octane gasolines and hence the ECU is programmed to accomodate that.

Rgds

I may be wrong, but I thought it is BMW's knock sensor which allows for variations in fuel octane and not so much the ECU?

How is the car's driveability (especially at low speed/during urban drives), fuel consumption and reliability after a remap/piggyback job? I'm tempted but these issues have got me somewhat concerned.

 

[DanPromote]

No it does not, a knock sensor's function is to warn the ecu when engine knocking occurs to prevent detonation. The ecu, when it gets the reading from the knock sensor then will compensate by retarding the ignition timing or increase fuelling until engine knocking is eliminated.

When an ecu is remapped, it is usually running on slightly lean fuel maps which is fine for n/a cars. You will notice better fuel consumption as well as more power on the whole range of power/torque curve.

 

[wglee]

Originally posted by DanPromote@May 29 2006, 09:34 AM
No it does not, a knock sensor's function is to warn the ecu when engine knocking occurs to prevent detonation. The ecu, when it gets the reading from the knock sensor then will compensate by retarding the ignition timing or increase fuelling until engine knocking is eliminated.

Purely for discussions' sake and with no intention whatsoever to flame anyone, I have a bona fide question. It is this:

I presume that the standard-setting ECU and knock sensor without remapping/piggybacking can compensate for variations in fuel octane. If that be the case, does it mean that, with the greatest of respect, variations in fuel octane as a factor is irrelevant when it comes to discussing remapping or piggyback jobs?

 

[ALBundy]

Asking a similar question twice...

IN the stock ECU setting, fuel octane variation is taken into account and hence the timing is not advance to the fullest.

When an ECU is remapped, the ignition timing is advanced to take advantage of the higher gasoline octane. Now, if someone uses say RON89 will he experience knocking or pinging? Answer is yes. The remapped ECU is probably not programmed to retard the engine timing significantly to prevent knocking or pinging when RON89 gas is used. As Dan mentioned knock sensor is just a sensor, its the ECU that retards/advance the timing.

 

[wglee]

Asking a similar question twice? If so, it was not intended. My apologies

Actually, I have more queries arising from ALBundy's reply eg.

1. Let's say we use 98 octane fuel as a benchmark for the highest octane fuel. With or without remapping/piggybacking, wouldn't the stock standard ECU in any event be able to advance the timing to the maximum permissible level before the onset of detonation, if 98 octane fuel is used?

2. Let's also say that 89 octane fuel is the benchmark for the lowest octane fuel. I think we can agree that a stock standard ECU has the ability to retard the timing to the level just before the onset of detonation, if 89 octane fuel is used. Taking ALBundy's reply to its logical conclusion, such an ability is removed after a remapping/piggy back job. Assuming the answer to 1 above is in the affirmative, can one conclude that the remap/piggyback job does nothing to the car's ability to take advantage of high octane fuel other than what is already provided by the stock ECU but would adversely affect its ability to cope with low octane fuel?

But never mind, lest I be seen as asking similar questions repeatedly

I must confess unreservedly that ECU remapping/piggybacking is technically all new to me, but I heard that:

A. Atmospheric conditions have a bearing on a car's performance eg. a car with a given ECU setting can be more powerful in colder countries due to the denser air etc, compared to the same car in a hot country. Rather than custom setting the ECU to suit different climates in different countries, every car's ECU has only 1 single compromised setting to suit all the different atmospheric conditions in different markets/countries.

B. A remapping/piggyback job is to, among other things, optimise the ECU setting for the particular climate and country where the car is operated/driven.

Are A and B above correct?

 

[DanPromote]

The answer is no. Stock ecu maps have limits where they cannot exceed. By remapping the ecu those limitations are removed and a higher limit is now set to improve performance. Whether the ecu can handle lower octane fuel depends on the ecu capabilities and the engine requirements.

On the question of atmospheric conditions, actually it refers to the air intake. The ecu will adjust its air/fuel ratio setting depending on the how much air goes into the intake, so in a way yes at different atmospheres you get different results because of the different air density. On stock ecu as explained earlier it will have safer settings (richer than required) while remapped ecu tends to have leaner air/fuel ratio settings to get better performance.

 

[wglee]

DanPromote,

Thanks for throwing light on the matter.

 

[ALBundy]

To further add on, with regards to the different air density, temperature and etc...the air mass sensor will take care of that. For instance when you are driving in a colder climate, the air mass sensor will send a specific reading to the ECU (air density, temperature and etc), and the proper amount of fuel will be injected into the combustion chamber. Remapping an ECU will not take away this ability of the ECU to varies the mapping to cater for various climate conditions and hence...we always feel the car to be more powerful at night where the air is denser!

So yup...its a NO-NO for both A and B.