Programmable ECU's and closed loop lamba control
Discussion
I was just wondering if anyone on here owns or has any experience of a catalytic convertor equipped road car with a fully reprogramable ECU that will easily meet MOT emission tests?
I was wondering about this because I've heard that it is extremely difficult (read expensive) to map them for proper closed loop idle control that is necessary for a modern cat equipped car to consistantly pass a emission tests.
As far as I understand it when the engine is idling the fuelling, ignition, and stepper motor are all constantly being varied to keep the rpm within a certain set idle range while at the same time the signal from the lambda probe is used to alter the fuelling to keep the exhaust emissions in effect 'clean'. Plus to make things slighly more complicated you've got the added problem of fluctuations in the rpm due to a varying loads on the alternator. Which all means that mapping it correctly is a very long process.
Well I've rambled on a bit, but basically what I want to know is if I fit a programmable ECU to my car will it be possible to map it (without costing thousands of £'s) so that it will consistenly passes emission tests?
I was wondering about this because I've heard that it is extremely difficult (read expensive) to map them for proper closed loop idle control that is necessary for a modern cat equipped car to consistantly pass a emission tests.
As far as I understand it when the engine is idling the fuelling, ignition, and stepper motor are all constantly being varied to keep the rpm within a certain set idle range while at the same time the signal from the lambda probe is used to alter the fuelling to keep the exhaust emissions in effect 'clean'. Plus to make things slighly more complicated you've got the added problem of fluctuations in the rpm due to a varying loads on the alternator. Which all means that mapping it correctly is a very long process.
Well I've rambled on a bit, but basically what I want to know is if I fit a programmable ECU to my car will it be possible to map it (without costing thousands of £'s) so that it will consistenly passes emission tests?
It all depends on how tight the emissions regs for your car are, this will depend on the year and are classified in terms of CO % and Hydrocarbon ppm's. I think modern 2003 requirements are in the region of 0.2% CO and 200ppm whereas my 1986 wedge is allowed up to 4.5% CO and 1200ppm! I run an aftermarker Emerald ECU on mine and can easily achieve 1% CO with 800ppm without a Cat and further reductions may well be possible.
Matt
Matt
If the management is fitted with lambda control, and most are, itll map itself in closed loop mode at idle anyway.
I dont think you need to worry too much about that part of the mapping, the hardest part with itll be part throttle and heavy loading at wot(wide open throttle) conditions id have thought.....ive gotta do all this soon meself...not looking forward to it.
I dont think you need to worry too much about that part of the mapping, the hardest part with itll be part throttle and heavy loading at wot(wide open throttle) conditions id have thought.....ive gotta do all this soon meself...not looking forward to it.
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