pre cat questions

[xinitialz]

ok sup lads how have you been


im finally gettin round to gettin my pre cat removed, as i've got a hole in my flexi wich is noisy and is causing an eml
im also gettin a new end-piece thingie welded on so ima have all the work done by a pr0 exhaust company and they have a question regarding the pre-cat removal:

Where exactly is the 1st lamba sensor located? cuz they fear it will give me an eml if the sensor is after the pre-cat.
Especially since im gettin an eml now while my flexi is kinda screwed. (is this normal? or should i fear my lambda is dead too?)

does any1 have some detailed pics or something? would be nice too

thx in advance for your replies ! cheers

 

[blue se2]

the first sensor is after the precat your screwed flexi is prob what is causing the eml as it will draw air in

 

[xinitialz]

the first sensor is after the precat your screwed flexi is prob what is causing the eml as it will draw air in

but if 1st sensor is after the precat, then i wonder how come it wouldnt give an eml after taking out the pre cat?? or does it check other things then the sensor at main cat?

 

[si.c1978]

because only used gasses travel down the pipe.
what he is saying is that unburnt fresh air will be drawn into the pipe by the exhaust gasses as they rush past the hole.

 

[xinitialz]

eml is gone, it happened cuz i floored it, i drove calmy for 20 miles and its gone now.


but now i still dont know why removing the pre cat wont give an eml since there is a lambda sensor behind it

 

[blue se2]

I just won't!! lol

 

[si.c1978]

it detects oxygen in the exhaust gasses not c02. hence if it drags air in from outside the sensor detects oxygen.

 

[xinitialz]

it detects oxygen in the exhaust gasses not c02. hence if it drags air in from outside the sensor detects oxygen.

thx alot mate thats what i needed to know !

i'll post update pics when new tailpipe is on cuz i used to have ly car tuned, but now its a bit more original ^^

 

[Hareng]

Got to do mine yet again, p.... me off every 8 months. Should tie me over for a couple of months before scrapping.
EML comes on when flexi leaking, can do a reset etc but will come back on within 200 mile or less, EML lights been on since last April cut the mileage down but still done 18k in ten months.

First is the oxygen sensor before main cat and well after pre cat, 2nd is the lambda sensor after the cat. Since mine wont undo i have to trace both sensors back and up in to engine and disconnect pull through and unbolt down pipe.
Flexi are around £6 to £18 i need another ive only got a 2" one here and short of tube soa trip to Ashley Exhausts again in Walsall. Last one i put on last year was a 4" x 2" bore.

 

[Hareng]

Still in the process of slapping yet another flexi on, well its tacked up but cant lay weld down before mig trips fuse out.

Its just reminded me as i took the downpipe off, where the pre cat fits its larger diameter than the rest of down pipe. Mine had almost cracked right round a few years ago just before it gets thinner.