After Market ECU - Which One, How Much & Why

[ampz]

I agree with CT. The programming is the more difficult part in ECU's. Your best bet is to do your research on the availability of tuning maps which will allow you to get fairly close to running right before you get on a dyno.

I played with a motec in a cordia which worked really well with a lancer evo base map. I was told by the owner that two 'tuners' couldn't get it going (trying to use cordia base maps). The owner had changed to a sonata 2 litre inlet manifold with mutli point injection. The cordia originally ran 2 injectors in the throttle body, i wonder why the original base maps didn't work

The point is, the base maps need to be fairly close to your engine requirements, there is enough data nowadays on mx5s that should make this a relatively straightforward excercise.

[Boags]

While we have a ECU thread in full swing...

How do piggyback computers work? I understand they intercept the signal from the air flow meter and change it to make the ECU think it is getting more or less air than it really is, and therefore changing the amount of fuel it puts in, but i thought that in closed loop the ECU will tune based on the oxygen sensor, and will just counteract what the AFM is sending anyway...?? Also, with turbo applications, the stock ECU will sh!t itself with any boost whatsoever, so how does the piggyback stop it from going into limp-home mode?

Confused...

Boags

[CT]

http://www.xede.com.au/about.php

http://www.haltech.com.au/interceptor.htm

My limited understanding of the interceptors is that they only apply a delta where the factory map is not good enough. The delta shifts the factory points back into a range that is more acceptable AFR wise through the fuel and ignition maps and then it goes on it's merry way...I think. But the ones above seem to do a bit more than that.

[The Pupat]

They intercept the AFM (and/or MAP if it has it), Water temp sender, O2, TPS, RPM, and CAS. and play with them until it acheives the \"desired results\".

The unique design of the **** prcessor ensures that all the safety features of the original ECU are retained whilst still delivering the power and torque gains you expect from a **** product

I love this how do you keep all the safety features in something that is specifically designed to fool the ECU into doing stuff it shouldn't do.

Anyway personally I'd stay away from the Wolf as from what I've been told it is rather difficult to get anyone to tune it in Brisbane/SEQ.

I don't like interceptor personally. I don't see the point I'd rather put a computer in that knows exactly what going on rather than one that is being fooled into working properly.

Anyway I would recommend calling PITS on the Gold Coast and asking Matt Spry what he can tune then go from there. If he can tune Wolf then go the Wolf otherwise I know he will tune Microtech, Haltech, and I believe Motec.

[JBT]

I understand they intercept the signal from the air flow meter and change it to make the ECU think it is getting more or less air than it really is, and therefore changing the amount of fuel it puts in, but i thought that in closed loop the ECU will tune based on the oxygen sensor, and will just counteract what the AFM is sending anyway...??

That's my understanding too for a fuel only piggyback. The thing is though, the OEM ECU will/may try to change the timing a bit because of the modified airflow info it gets.

Also, with turbo applications, the stock ECU will sh!t itself with any boost whatsoever, so how does the piggyback stop it from going into limp-home mode?

I don't think the ECU cr@ps itself. It just doesn't know what to do because the airflow and other demands don't make sense to it. AFAIK, a fuel control only piggy back won't help in that case, but an extra piggyback will be required for boost and then for ignition timing etc.

[Boags]

This is the bit i'm confused about... I know heaps of people use piggybacks for turbo setups, the fcon-mini comes with the HKS kit and greddy emanage with the greddy kit, so how do they convince the ecu that the world isn't ending?

And does the B6 ECU try to adjust timing? I thought the timing was fixed, which is why you can do the timing fiddle on them and the ECU doesn't try to change it...

Boags...

[ampz]

It has to do with the rising rate fuel presurre regulator Boags. It has a vacuum line which on boost sense, raises the rate of flow of fuel (ie, ups the p[ressure down the line) therefore, the same duty cycle (or injector opening time) squirts more fuel on boost.

I may however be completely wrong

[Boags]

Ahhh, that makes sense. It is actually flowing more fuel than it thinks it is... So you firstly tell it isn't getting as much air as it thinks it is, so it doesn't go into limp home mode, then make it pump more fuel... Genius, if that is correct then I understand...

Cheers,

Boags

[JBT]

This is from the Autospeed site concerning the Jaycar DFA but also interceptors/piggybacks in general

The Shortcomings

Let’s be realistic – all products and modification approaches have shortcomings. So what are the DFA’s?

Firstly, it is an interceptor. All interceptors – no matter how fancy their names, initials or advertising – have negatives. The most major is that the ECU needs to be confused into doing what you want. For example, if you reduce the load signal coming from the airflow meter, the mixtures will go leaner – but the ignition timing is also likely to advance a bit. For this reason it is important that the engine be monitored for detonation when the mixtures are being altered.

Secondly, you can’t change the mixtures away from 14.7:1 when the car is in closed loop (that is, when the ECU is using the feedback of the oxygen sensor(s) to determine mixtures). Again, that’s the same with any interceptor. (However, as mentioned above, the DFA can be used to intercept the oxygen sensor signal – but that’s another story. Also, when major engine management changes like injector or airflow meters are made, the DFA can be used to bring the mixtures back into the range of closed loop adjustment. The ability of the DFA to be able to change the airflow meter signal across the full load range is therefore very important in all cars.)

Finally, the DFA comes in kit form and so needs to be built. As with all electronic kits, if you make a mistake in the construction process, it’s likely that the DFA won’t work. (But in that case spend more money and buy a pre-built kit.)

[The Pupat]

Ahhh, that makes sense. It is actually flowing more fuel than it thinks it is... So you firstly tell it isn't getting as much air as it thinks it is, so it doesn't go into limp home mode, then make it pump more fuel... Genius, if that is correct then I understand...

Cheers,

Boags

You could also accomplish the same thing by putting in bigger injectors and telling the computer for all load points there is less air flowing than there actually is.

[Sean]

As alwaysI am biased to what brand you should buy, but since teh topic is resurrected I'll say no matter what you purchase make sure the logging software is good and allows you to log all channels at once.

I can run a log that shows me timing, injector ms, intake temp, water temp, boost/vacuum, rpm, afr and exhaust temp all on teh one graph.

I never though it was that useful, but we've found it indispensible in sorting out the \"perftect tune\" for teh car, if you have a small flat spot or minor glitch in teh car, it's usually quite easy to locate if you can pull teh data log and exmine exactly what teh engine was doing at the point where the glitch occuurs...

[jules]

That sounds like really good advice Sean


Jules

[The Pupat]

As alwaysI am biased to what brand you should buy, but since teh topic is resurrected I'll say no matter what you purchase make sure the logging software is good and allows you to log all channels at once.

I can run a log that shows me timing, injector ms, intake temp, water temp, boost/vacuum, rpm, afr and exhaust temp all on teh one graph.

I never though it was that useful, but we've found it indispensible in sorting out the "perftect tune" for teh car, if you have a small flat spot or minor glitch in teh car, it's usually quite easy to locate if you can pull teh data log and exmine exactly what teh engine was doing at the point where the glitch occuurs...

So you'd reccommend Motec then ;)

[Sean]

As alwaysI am biased to what brand you should buy, but since teh topic is resurrected I'll say no matter what you purchase make sure the logging software is good and allows you to log all channels at once.

I can run a log that shows me timing, injector ms, intake temp, water temp, boost/vacuum, rpm, afr and exhaust temp all on teh one graph.

I never though it was that useful, but we've found it indispensible in sorting out the "perftect tune" for teh car, if you have a small flat spot or minor glitch in teh car, it's usually quite easy to locate if you can pull teh data log and exmine exactly what teh engine was doing at the point where the glitch occuurs...

So you'd reccommend Motec then ;)

If you have the $$$ and your tuner has the knowledge, definately.