Catalytic meltdown
Catalytic meltdown
(OP)
How lean is too lean for a modern (non-lean burn) car and how rich is too rich? Reason I'm asking is my new 4 cylinder Mazda 3 is going through catalytic converters like shit through goose. The dealer has been unable to solve this problem. Looking at the fuel mixture and its ECU, Its WOT fuel mixture is set at mid 11.5:1 air fuel ratio and part throttle is stoich 14.5:1. I want to do my best to keep the cat safe and prevent meltdowns. Do you think it's set to run too rich? Would 12.5:1 be a safer ratio given I retard spark to prevent knock? thanks...





RE: Catalytic meltdown
Which engine? Skyactiv 2.0 litre?
Warranty?
Unless you are driving like a madman, it should be running at stoichiometric the vast majority of the time and it should be designed to handle that, and it should not cause a problem.
Something else is wrong.
RE: Catalytic meltdown
If you are not able to use the vehicle as a trouble free black box appliance but rather are being inconvenienced with check engine lights, failure to pass emission tests required for registration, or any other issue related to engine malfunction, it is the manufacturer's responsibility to resolve such issues whether under emissions warranty, implied warranty and/or "fitness for purpose".
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz
RE: Catalytic meltdown
RE: Catalytic meltdown
Is this a common problem with these engines?
Those ratios look perfect.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube
RE: Catalytic meltdown
So, you modified/flashed the ECU? Far as I can recall, the Mazda 3 does not have a spark advance lever (like a Model T), nor any other way to tweak spark timing outside of warranty-voiding mods.
RE: Catalytic meltdown
A tidy mind not intelligent as it ignors the random opportunities of total chaos. Thats my excuse anyway
Malbeare
www.sixstroke.com
RE: Catalytic meltdown
RE: Catalytic meltdown
Otherwise, they run great.
Mike Halloran
Pembroke Pines, FL, USA
RE: Catalytic meltdown
The Skyactiv engines don't have EGR or secondary air injection, and that's common nowadays. Where necessary, the EGR and secondary-air functions are accomplished by playing with the variable valve timing.
RE: Catalytic meltdown
Where those numbers from fuel trims? And how do you know they are accurate?
What things have been done to try to fix the problem? Are sensors reporting correctly?
RE: Catalytic meltdown
RE: Catalytic meltdown
Very close visual/tactile inspection, the kind that dealer techs do not have time for, might be worthwhile.
Mike Halloran
Pembroke Pines, FL, USA
RE: Catalytic meltdown
RE: Catalytic meltdown
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Catalytic meltdown
Was the converter melted or did it just break apart?
RE: Catalytic meltdown
RE: Catalytic meltdown
To my knowledge, there is not a pattern of catalyst failure on these cars. If your failure were really due to the delayed cold-start ignition timing then they would ALL be failing in this manner - but they're not. Something's wrong with your particular car; it just hasn't been found yet.
It's not the ECU programming, because that's the same on all of them.
How's your fuel consumption? Manual or automatic?
Do you drive it gently during warm-up for the first couple of minutes, or is the accelerator binary (0 or 1, off or on)?
Which part of Canada are you in? Mazda has a healthy market share in Quebec. It gets cold there. Still no pattern of catalyst failures there, to my knowledge.
If you're on facebook, I can put you in contact with someone who until a year or so ago worked in the technical department of Mazda Canada (he has certainly dealt with the Skyactiv powertrains). He's moved on, but still probably knows a thing or two about them. Failing that, I can be the intermediary here in the conversation. I will link him to this thread.