Ask Xulfiqar - An Automotive Encyclopedia

[umairjamil6]

The car will burn it completely lean when the cat is removed? With the cat it runs richer? So the people who remove cats are burning up their engine at low loads? @Xulfiqar please explain.

[Xulfiqar]

The ECU runs the engine very rich to "start" the cat converter, once the engine comes up to temperature and the AFR sensor/regulating oxy sensor/upstream - starts to respond, the ECU starts to run off the learned trims and sends waves of fuel enrichment and subsequent waves of lean fire so the cat converter remains in its critical working temperature and keep the exhaust clean.

If you remove it - the 'waves" wont do anytihng as the cat is missing, you will just get raw exhaust

[umairjamil6]

So no substantial difference regarding lean or rich burn?

[Xulfiqar]

not understanding your point.

[umairjamil6]

Does The ecu know that the cat has been taken out and keeps working as it was? The car doesnt run leaner as posted by @Thinking.

[saboor73]

Does The ecu know that the cat has been taken out and keeps working as it was? The car doesnt run leaner as posted by @Thinking.

It does

Because without cat con required back pressure wont be there also in cars like honda civic with liquid cooled intake manifold engine wont ever reach temperature its designed to work in

[umairjamil6]

Back pressure isnt really required by cars. And simply removing the catcon doesnt reduce the back pressure to 0. Please elaborate your point regarding working temperature. If we remove catcon the engine wont reach the operating temp? Doesnt sound right to me but i am sure the experts can throw some light on it.

[Xulfiqar]

the ecu only knows that the cat is bad from the post o2 sensor,

The cat has no effect on running lean or rich

[Thinking]

didnt break it. i think previous owner tried to get it cleaned with sweep and ended up dissolving it

whats the suggestion regarding replacing it from the options i mentioned above.

[Xulfiqar]

Find an original equipment part, the replacement cat converters for lower price are simply less in materials,

Which negates your repair in its entirety.

[Thinking]

hmmm ok thanks.

[dayrider]

Call up Honda 2S dealers, ask them for a new cat con. They will get it by order, will probably cost around 70k

[S-Tech]

@Xulfiqar

Sir, I was having overnight battery drainage issue for last few days.
I decided to change the battery and installed a brand new 12v, 40AH,
330CCA, Daewoo DL55 maintenance-free battery in my Honda City 13 i-VTECH
2015 yesterday.

When I parked my car last night I checked battery voltage it was
12.75 v. I check voltage again in morning and it dropped to 12.52 v. I
think it is a signification voltage drop overnight (no tracker installed
in the vehicle), is it normal or I should be worry?

If it isn't normal then how could I diagnose the issue myself - I can't find an electrician due to local down in the town.

Please advise.

Thanking you in anticipation.
Sami Jadoon

[Xulfiqar]

Hi,

No this is not a true test, your battery will lose some voltage, a car with parastic loss will drain the battery to 11v overnight.

Test it this way.

Park it for 3 days, then try starting it, if the starter labours to start. You have a weak battery.

[S-Tech]

Thank you for your prompt response

I'll try that and let you know.

BTW, how could a brand new battery be weak?

[Xulfiqar]

The battery maybe new to you - but may have sat on a shelf for ages without a battery maintainer/tender.

[S-Tech]

That could be a case. Is there a way to check manufacturing year/month of a battery?

[Xulfiqar]

Its on the battery itself.

and do a capacitance test on the battery - which most shops cannot do in Pakistan as that tester is alien to them. - they still rely on carbon pile.

[pwuser155913790095]

@Xulfiqar i have previously read owner manual of 1krfe and it has mentioned valve clearance inspection which in local language is tappet adjustment and here all mechanic says it dosent need these adjustnent but its nentioned in manual is it a periodic maintnance in modren toyota engines?

[Xulfiqar]

All engines wear down and tappet clearance change, they are inspected and adjusted as required, The clearance range is pretty large though.

in case of 1KR-FE and other new toyota engines the tappet is adjusted by changing the entire bucket (daboo) - which is not done in Pakistan because they are expensive, this is why machinists grind down the valves which grinds away the hardened skin of them and they wear 100 times faster.