10-05-2012, 10:07 AM
The problem is right, you have to think how the ECU works...
Well what inputs does it have:
- MAP - Manifold pressure
- TPS - Throttle Position
- Lambda - Exhaust O2 Content
- CLT - Coolant Temperature
- CPS - Cam Position Sensor
- CAS - Crank Angle Sensor
They're essentially all the inputs for one of these engines - then you look to how the ECU calculates what mixture to give the engine - it looks at the RPMs deduced by the CAS and CPS - knowing that it can also know when to fire the spark and Injectors (I'm 99% sure the injectors on 1.8s are Semi-Sequential)... It then looks at the Throttle Position and MAP - essentially MAP and Throttle Position read the same value, it's just for transients where the manifold is filling or emptying where the TPS is used over MAP, then it looks at Lambda - which is ONLY for part throttle correction, it will do NOTHING on full throttle and then uses CLT to simply enrich the mixture at low coolant temps...
The 1.8 MAY have an IAT sensor, but I'm not 100%, so if it does, it'll compensate if it's hot out...
The ECU does NOT know how much air is going intoand out of the engine, it can correct itself at part throttle on the Lambda, that's for cruising economy, not to mention it doesn't work when cold and not at full throttle...
How does the ECU know how much air is going into the engine - well that's your volumetric efficiency table - VE - that is HARD CODED into the ECU - VE being if there was NO restrictions on filling the cylinders (so the full 450cc being drawn in per stroke) being 100%, how many percent is ACTUALLY being drawn in - on a 1.8, somewhere in the reigon of 80% at peak torque, obviously this changes versus RPM and throttle position... Therefore it knows how much air *SHOULD* be going into your engine, there's no feasible way that the ECU can possibly know in actuality how much air is going in... If everything is left as standard, the ECU has a damned good idea knowing MAP, TPS and RPM how much air actually is going into the engine...
Once it knows how much air is going in, it can then see what the required mixture should be, it then throws in the correct mixture once going through the Lambda and CLT sensors and correcting it slightly for that...
So essentially - there is no way the ECU knows how much air is going into the engine, it hasn't a clue - now if you had a MAF sensor shoved on the end of it, it can then tell - that's how things like MR2 turbos, you can turn up the boost and they'll make 350hp on stock management... A non-MAF ECU hasn't a clue! That's not taking into account the spark calculations for adjusting ignition timing, that's pretty much set as it is, and won't change apart from on cold start...
This is why they need to be remapped, I'm not saying for a second that your ECU isn't shagged, Niall, it probably is, but bolting things to a Mafless ECU won't do anything - again another reason GTi6s don't improve power by bolting things on, they haven't a clue what's actually going on, just predefined values.
Sorry for the essay, but people are saying that the ECU will "learn" - it really won't, it'll learn a bit from the lambda at part throttle, but at WOT it can't do anything, it's hard coded in and there's no way of it correcting for more/less airflow.
Well what inputs does it have:
- MAP - Manifold pressure
- TPS - Throttle Position
- Lambda - Exhaust O2 Content
- CLT - Coolant Temperature
- CPS - Cam Position Sensor
- CAS - Crank Angle Sensor
They're essentially all the inputs for one of these engines - then you look to how the ECU calculates what mixture to give the engine - it looks at the RPMs deduced by the CAS and CPS - knowing that it can also know when to fire the spark and Injectors (I'm 99% sure the injectors on 1.8s are Semi-Sequential)... It then looks at the Throttle Position and MAP - essentially MAP and Throttle Position read the same value, it's just for transients where the manifold is filling or emptying where the TPS is used over MAP, then it looks at Lambda - which is ONLY for part throttle correction, it will do NOTHING on full throttle and then uses CLT to simply enrich the mixture at low coolant temps...
The 1.8 MAY have an IAT sensor, but I'm not 100%, so if it does, it'll compensate if it's hot out...
The ECU does NOT know how much air is going intoand out of the engine, it can correct itself at part throttle on the Lambda, that's for cruising economy, not to mention it doesn't work when cold and not at full throttle...
How does the ECU know how much air is going into the engine - well that's your volumetric efficiency table - VE - that is HARD CODED into the ECU - VE being if there was NO restrictions on filling the cylinders (so the full 450cc being drawn in per stroke) being 100%, how many percent is ACTUALLY being drawn in - on a 1.8, somewhere in the reigon of 80% at peak torque, obviously this changes versus RPM and throttle position... Therefore it knows how much air *SHOULD* be going into your engine, there's no feasible way that the ECU can possibly know in actuality how much air is going in... If everything is left as standard, the ECU has a damned good idea knowing MAP, TPS and RPM how much air actually is going into the engine...
Once it knows how much air is going in, it can then see what the required mixture should be, it then throws in the correct mixture once going through the Lambda and CLT sensors and correcting it slightly for that...
So essentially - there is no way the ECU knows how much air is going into the engine, it hasn't a clue - now if you had a MAF sensor shoved on the end of it, it can then tell - that's how things like MR2 turbos, you can turn up the boost and they'll make 350hp on stock management... A non-MAF ECU hasn't a clue! That's not taking into account the spark calculations for adjusting ignition timing, that's pretty much set as it is, and won't change apart from on cold start...
This is why they need to be remapped, I'm not saying for a second that your ECU isn't shagged, Niall, it probably is, but bolting things to a Mafless ECU won't do anything - again another reason GTi6s don't improve power by bolting things on, they haven't a clue what's actually going on, just predefined values.
Sorry for the essay, but people are saying that the ECU will "learn" - it really won't, it'll learn a bit from the lambda at part throttle, but at WOT it can't do anything, it's hard coded in and there's no way of it correcting for more/less airflow.
