why do you leave the second lamba sensor diconnected

[jpmad4it2]

hey,

I was just wondering why I, and some others chose to leave the second lamba sensor disconnected on our decats?

Someone was asking why it was like that on my car, but i totally forgot the reason behind it!! D'oh! I'm just curious.

Also what is the disadvantage of connecting up the second sensor (my janspeed decat has 2 slots for both sensors but i blocked the second one up as most people said to do so)

regards J

 

[RSTuning]

Because if you leave in the exhaust system the ECU will think the cat is not doing it's job and in turn bring on the toxic fume light. I assume the Lambda is actually still plugged into the wire?

Paul

 

[jpmad4it2]

Because if you leave in the exhaust system the ECU will think the cat is not doing it's job and in turn bring on the toxic fume light. I assume the Lambda is actually still plugged into the wire?

Paul

my second lamba is disconnected from the decat, but is still connected to the car (just tied up underneath). My emissions light is on permanently. I have a hole (which is blocked up at the moment) for the second lamba sensor to go in on the decat.

Im having problems with it still and was wondering if i should fit the second sensor, or take off the sensor completely i.e. disconnect it from the car too. The problem is sometimes the car will suddenly just drain of all power. It happens on acceleration. The more you put the accelerator down the worst it gets. Its not to with the car being cold either as it can do it at anytime. It just wont go over 3000 revs when it happens. Its similar to the well known cold-start problem but it happens all the bloody time. Some people here said it could be a fueling problem, injection problem, or i may need a remap (which i cant afford yet). I need someone to look at it really.

What do you suggest mate?

 

[Turkish]

unplug the sensor and remove it from the car. I had a decat on my 172 and took the second lambda off totally and had no issues with the light coming on.

 

[The Fatty]

yeah remove it completely, that way the ecu thinks its a model car that only had 1 sensor, and works fine.

 

[RSTuning]

Not sure if the clio is the same as the megane but it is possible to tell the ecu it only has 1 sensor using the clip on the megane.

Paul

 

[jpmad4it2]

Thanks guys i will take the sensor off completely and reset the ECU by disconnecting the battery yeah? To clear it??

 

[BRUN]

check your coolant sensor wiring mate, common fault

 

[jpmad4it2]

Thanks Brun I will have a look at that.

EDIT - i have disconnected the wire from the underneath of the car and have taped it up, but the emissions light is still lit up so i am disconnecting the battery to see if it resets.

@BRUN sorry for being a dumb arse but where is the coolant sensor wiring?

 

[jpmad4it2]

disconnecting the battery didnt get rid of the emissions light. Guess i will have to see how it goes unless anyone has any ideas?

 

[Guy]

couldnt you buy a lamba sleeve??

http://www.gmcmotorsport.co.uk/price.html#manifold

ring GMC up and ask them about it.. theyre very knowledgable people..
im sure it 'mimmicks' having slightly dirty air or something?

bought 4-1 manifold and forged pistons from them before.

 

[wide]

connect both lambar sensors up, firstly you've got nothing to lose, all that happerns is the emmissions light comes on, & as yours is on anyway, no lose . then dissconnect the battery and see what happerns. i've got a 172 mk2, & both are plugged in & the light has stayed off! also read the bit on clearing faults.

 

[Gaz_]

it will 100% be a faulty lambda probe or wiring to the first sensor (closest the engine) i had the exact same fault, some times fine, sometimes a right pig to drive, the more the pedal squeezed, the more it spluttered etc...... make sure you have the second probe connected, but taped up, now mine actually turned out to be the plug to the probe itself, make sure this is clean and not full of water etc, ifthat looks ok, fit a new probe (not much £££) the light will eventually go out on its own accord, mine took about 3 days.

this will solve it mate

 

[The Fatty]

could he not just swap the sensors over, and leave the scond one off? saves buying that way!

love the updates btw!

 

[CHRIS172CUP]

I only have one sensor on mine and the light is on all the time. Don't bother me, it sounds goooood

 

[JimmyMac81]

I had a similar problem with my Fiesta ZS when i got a 4-2-1 Manifold and Race System Zorst fitted. My engine management light was constantly on due to the fact that i had 2 Lamda sensors. I could still have one connected but obviously because i removed my CAT there was nowhere for the other to go.

I just ended up disconnecting it and got used to my Engine Management light on!

 

[Ali]

Plenty of people on here have/had both sensors in and the light stayed off...?

 

[16v_jon]

i have both sensors in brings up the light every 700 miles for 50 miles then goes out i feel i loose power with the second one disconnected

 

[jpmad4it2]

couldnt you buy a lamba sleeve??

http://www.gmcmotorsport.co.uk/price.html#manifold

ring GMC up and ask them about it.. theyre very knowledgable people..
im sure it 'mimmicks' having slightly dirty air or something?

bought 4-1 manifold and forged pistons from them before.

what do you do with the lamba sleeve??

 

[jpmad4it2]

it will 100% be a faulty lambda probe or wiring to the first sensor (closest the engine) i had the exact same fault, some times fine, sometimes a right pig to drive, the more the pedal squeezed, the more it spluttered etc...... make sure you have the second probe connected, but taped up, now mine actually turned out to be the plug to the probe itself, make sure this is clean and not full of water etc, ifthat looks ok, fit a new probe (not much £££) the light will eventually go out on its own accord, mine took about 3 days.

this will solve it mate

how'd you mean have the second probe connected and taped up?

think ill get some extra probes from the scrap yard and try them.

 

[rmccardal]

Unplug the second sensor on a 182 and the light WILL come on.

 

[jpmad4it2]

im not bothered about the emissions light - it can stay on for all i care - i just want the power problem sorting out. So i guess ill get the second sensor plugged in, and if that doesnt work i will get some new plugs and sensors from the scrap yard

 

[jpmad4it2]

spoke to the guy at GMC. Ordered a lamba sleeve. He said once i fit the sleeve i need to get the ECU wiped to reset everything. So where can i go for that? how much will renault charge ? or can someone on here do it cheaper?

 

[Gaz_]

trust me you really dont need to do all that! i mean leave the second one connected to the plug, but insulation tape it up, then zip tie it to something underneath the car, then you need to plug up the second hole. This WILL work

have faith my friend

 

[The Fatty]

oh right...i thought you were reseting ecu anyway! the easyest way to set it back to factory settings, and let it re-initialise its self is to simply disconect the battery for 30mins/hour. when you re-connect, the ecu starts up fresh...

 

[jpmad4it2]

trust me you really dont need to do all that! i mean leave the second one connected to the plug, but insulation tape it up, then zip tie it to something underneath the car, then you need to plug up the second hole. This WILL work

have faith my friend

the second hole is already plugged up. Instead of insulating it i will place the sleeve i have bought to see if it works, and i will reconnect the sensor to the car- yeah?

I am getting conflicting ideas here!!!

People are saying leave the second sensor connected and block the hole up on the decat - which is how i had it in the first place - so that didnt work.

Others are saying disconnect the sensor from the car and from the decat - which is how i have it now - and its still not solved the problem.

I dont think unplugging the battery resets the ECU? or am i wrong here?

 

[Gaz_]

i've got the same car as you and sounds like the same problem too!, i really do beleive its some kind of lambda probe or wiring problem..... i'd deffo change the 1st probe

forget the ecu

 

[jpmad4it2]

i've got the same car as you and sounds like the same problem too!, i really do beleive its some kind of lambda probe or wiring problem..... i'd deffo change the 1st probe

forget the ecu

well ill get a new probe for the 1st sensor and try that - or i could swap the 1st sensor with the 2nd, and put the sleeve on the second? or if one of the sensors is faulty will the problem just persist?

 

[The Fatty]

I dont think unplugging the battery resets the ECU? or am i wrong here?

yeah it does if you leave it off long enougth...

 

[jpmad4it2]

well i had it unplugged for a good hour and 20 mins so it should of done it.

 

[The Fatty]

like gaz said, its not your ecu...have you tryed swapping the sensors over as a test?

 

[jpmad4it2]

like gaz said, its not your ecu...have you tryed swapping the sensors over as a test?

no - but i thought if one of them is faulty it wont matter if i swap them around?

 

[The Fatty]

if the 1st ones faulty, then it will produce the fault...like people have said you dont need the second one at all, so just leave it off while you test it....

 

[jpmad4it2]

if the 1st ones faulty, then it will produce the fault...like people have said you dont need the second one at all, so just leave it off while you test it....

ah right i follow. ill swap them around this wkend.

Do i need the second one actually unplugged from the car too? Or should i plug it in for the time being?

 

[The Fatty]

if i was you, id try it with the second sensor unplugged to start with, then connect it if need be! let us know how you get on, you seem to be good with updates! gd luck!

 

[jpmad4it2]

if i was you, id try it with the second sensor unplugged to start with, then connect it if need be! let us know how you get on, you seem to be good with updates! gd luck!

ill let ya know