Catalytic Converter - new lambda sensor needed?

Horizon81

I should probably get a Haynes manual, but will try and see if I can remove it. So the first sensor is near the manifold at the front? Where is the second one? If it's connected after the cat, where does the other end of the cable go? All the way to the engine or is there a socket under the car somewhere?

Also, the car mainly does short runs. Has done for the first 7 years of its life and the first cat lasted that long. It's still doing short runs but this cat lasted 4 months? I don't get it. I know it's good for cars to get a good run out once in a while, but would this prolong the life of the cat?

tbourner

That's why I said you might need to reset the ECU if the garage didn't. It would be running with the wrong mixture and could soot up the new cat quicker.

Horizon81

By reset the ecu do you mean just unclip the negative terminal on the battery for a few hours? Besides, i thought the sensor would adjust accordingly if a new cat was fitted.

tbourner

Completely depends on the car, most ECUs learn over time and remember the last X amount of time, so if the old cat was knackered it would be fuelling accordingly and would be wrong for a new cat, so if the new cat is fitted and the ECU not reset, it would fuel for the old cat for that X period of time until it learnt the new values.
This is all case dependant though, some cars may learn straight away I don't know, I've just always reset an ECU if I change anything fuelling related. You can unhook the battery or if you know where the ECU fuse(s) is just pull it out. There may even be a way to reset it from inside with combinations of pressing pedals and turning the ignition - but again it's model specific you'd have to ask an owners club.

epninety

Horizon81 wrote: »

epninety - what makes have you seen fail? This one was made by 'Fuel Parts' - is that a reputable aftermarket manufacturer?

Also - how easy is it to remove the sensor? Can't say I'd ever spotted any wires coming from the cat to the engine!

Fuel Parts is a distributor, not a manufacturer afaik, so the actual manufacturer might vary from month to month. Also I note they sell two ranges 'Premium' and 'Aftermarket', presumably to get around the law on only fitting type approved cats? Make of that what you will.

Two problems to removing the lambda sensor - it's often hard to get easy access to it to swing a decent tool - plus since it's screwed into the exhaust it tends to be cooked on tight, and and soot buildup on the inside can make it tighter as you try to loosen it.

Lum

Another reason why, if it's the secondary, pointless, lambda sensor to just ignore it and do the resistor mod. You can leave the damn thing in the hole.

I hate lambda sensors, they fail more often than the systems they're supposed to be monitoring.

Horizon81

Lum, I agree with you wholeheartedly. Everyone managed ok before the engine malfunction light was invented! The car in question drives fine but this bl00dy malfunction light is annoying, basically bullying you into changing parts until it goes out. As I understand it, the warning code could mean the cat or either of the 2 lambdas is at fault. I can see why people take the bulb out!

Lum

I was a little extreme in my last post. I like the first lambda sensor as, when working, it does save you money as it can help adjust the air/fuel ratio much better than we ever could by hand. I hate how long they last though.

Whoever came up with the idea of the second one though. I can think of a much better place to shove that lambda sensor.