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Discussion Starter · #1 ·
A senior mechanic at my Mitsi Dealership told me I could use leaded petrol in my new Tommi because it was de-catted and unleaded petrol was only necessary if you have a catalytic convertor.Is this correct as leaded has a higher octane rating, sounds like ****** to me ,but maybe Im wrong?
 
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Discussion Starter · #2 ·
You always hear these stories from people. I think it's bs. Leaded here in France is 97 RON and leaded 95 or 98. I wouldnt take chances.
 
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Discussion Starter · #4 ·
The car will run on LRP 97 RON fuel however search through earlier threads on this board first. Apparantly the turbine and O2 sensors get eaten by the stuff they've replaced the lead with (potasium or sulphur - which are both nasty little chemicals, just drop some sulphur down the sink and stand back or let potasium see fresh air and you'll see what I mean)

If there's a chemist out there - please confirm I got the chemicals the right way round http://www.ltregister.f9.co.uk/graphics/happy1.gif border|EQU| 0 align|EQU| absmiddle >

Cheers,

Mark
 
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Discussion Starter · #6 ·
Yep leaded fuel or LRP will eventually plate the lambda (O2) sensor in crap making it useless.
I have rapidly come to the conclusion that Mitsubishi garage mechanics know #### all about cars let alone Evo's. (Obviously there are exceptions but I have yet to meet any.)
 
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Discussion Starter · #7 ·
Thank you for your replies,but surely as I have fitted a de-cat pipe I no longer have lamba sensors?
 
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Discussion Starter · #9 ·
You most definitely do still have a lambda sensor and it's correct functioning is very important to the health of your engine and your fuel economy.
The Mitsubishi ecu has two phases of operation.

1. Closed loop where it is constantly monitoring the lambda output and adjusting the fuel injector opening times to achieve a near stoichometric air/fuel ratio (lambda|EQU|1, air/fuel mass ratio 14:1 (kg)- average mixture mass ratio for complete fuel combustion). This mode is active at idle and low load/throttle openings.

2. Open loop - the ecu disregards the lambda sensor voltage and uses the pre-programmed ecu map. This mode is active under acceleration / high load engine conditions.

Fitting an air/fuel meter will allow you to see the engine management switching between these two modes of operation. In mode 1 the lambda sensor voltage constantly cylces up and down around stoichometric (14:1) and is seen to switch to a constant rich value (12:1?) on hard acceleration. If you fit an aftermarket gauge bear in mind that the voltage output does not operate a linear relationship to the lambda value but jumps steeply at lambda|EQU|1.
 
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Discussion Starter · #10 ·
Thank you for your advice guys and Lightspeed ,what can I say your knowledge blows me away I can now say I understand the function of the lamba and that 4star is not an option.Thanks again.
 
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