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Leaving lambda sensor disconected
- Thread starter c5 swh
- Start date
That seems a little unlikely TBH, I think you made a mistake in your maths or there was some other problem.
My maths? I just read the dash display. Plus, the needle was practically dropping at the speed of light.
This is how it was fitted: attached using relevant tools and bolts etc. , then without lambda as it was stuck to cat. , then there were holes all around it so it sounded like a bag of nails. The pre cat join is corroded and can only be sealed with putty/heat paste. I didn't do that last time and it sounded s**t, and drank too much. This time round I'll fit the sensor and paste it up.
This is how it was fitted: attached using relevant tools and bolts etc. , then without lambda as it was stuck to cat. , then there were holes all around it so it sounded like a bag of nails. The pre cat join is corroded and can only be sealed with putty/heat paste. I didn't do that last time and it sounded s**t, and drank too much. This time round I'll fit the sensor and paste it up.
No way would just the removal of the rear sensor cause your mpg to drop to 5 on a 182, unless you only tested it while accelerating up a steep hill in 1st gear while towing a portacabin.
If my post cat lambda is unplugged then it runs like a smelly bag of 4 week old s**t. All I've done is put an old lambda in, left that disconnected and then used a working lambda, plugged that in and cable tied it under the car reading fresh air.
Runs lovely, no engine lights and is fairly well known as the best way of doing it.
Runs lovely, no engine lights and is fairly well known as the best way of doing it.
Jekyll
ClioSport Club Member
I had my post car lambda tucked into the heat shield. Never had any dramas, nor did I notice a change in MPG.
celicaturbolly
ClioSport Club Member
Kona , Old Defender
It would have to be in order to return only 5mpg, as if it was on a normal run then thats your car using approx 8 times as much fuel as its meant to, and if you go from an AFR of around 15:1 on cruise like they run normally, to an AFR of around 2:1 on cruise, then the first thing that would happen is that the negine wouldnt run at all, it is literally just not possible to get a 172 down to those figures no matter how out of tune the engine is as you simply dont have enough air to burn that much fuel inefficiently even if you ran it monstrously rich and you massively retarded the timing, what you are saying just is not physically possible with one of these engines just by altering the tune.
Right, OK then. It hit those figures while crawling through (up) a village. I was watching the numbers drop every second. Heavy traffic. I've heard the dash can give a different reading to reality. But either way what happened happened and I'll be fitting it with lambda and sealant his time.
Well it is upto other people if they think your very low reading was due to:
a) an error in your approach to analysing data and coming up with a number
b) the fact you had no lambda sensor
Having frequently achieved 45+mpg while not having a second lambda working on 172s in the past, my personal opinion is that the reason was a) but others can each decide for themselves how much weight to put against your "it will do 5mpg" statement.
At least now we have a more thorough picture of how the figures were gathered, so thanks for the additional info, I feel it clears things up a lot from your original statement, and I like stuff to be accurate on here, so am now much happier
loggyboy
ClioSport Club Member
Before this escalates, could this be down to Cuplica making a typo? did he mean reduced by 5mpg?
It could have, although if it was its weird he hasnt corrected himself yet given the amount of discussion on the subject since all centred around it being 5mpg not dropping by 5mpg.
TBH if it was only dropping by 5mpg when driving up a hill in a village in a low gear then it sounds like it had no effect at all
Well yes of course it is, you're not going anywhere, so really you're getting 0mpg.
PH2 172
Ah,maybe the penny will drop eventually.
The second sensor wont make the car run badly, it puts the light on but doesnt effect the main fuelling, its only real job is to detect if the car is working correctly or not.
It sounds like you have some other problem, although the only problem ive ever see give single figure mpg is if the speed signal to the ecu is wrong so it doesnt think you are doing anywhere but that is very obvious when it happens cause the speedo doesnt work.
It sounds like you have some other problem, although the only problem ive ever see give single figure mpg is if the speed signal to the ecu is wrong so it doesnt think you are doing anywhere but that is very obvious when it happens cause the speedo doesnt work.
I'm stuck as to why the mpg dropped so low. It was a very leaky precat join and the sensor completely unplugged, it surprised me how badly it reacted. Its a gamble for me to try and remove the lambda but it has to happen if only to solve the saggy exhaust and blowing. Its sucking the fun out of owning such a nimble car.
PH2 172
Clearly not yet.Parked with the handbrake on and with the engine running= no miles to the gallon.
PH2 172
Sleep on it,refit the cat with the unremovable lambda,and see how it goes.
I`m puzzled by the saggy reference,either the mounts have had it,or the pipework has fractured at some point.
You never stated why you want to fit the decat in the OP?Looking for a performance gain,or because of a defect with the original cat?And the decat is the cheapest option?
Also,as I`m trying to make sense of this,this is a pre-owned decat,with a damaged O2 sensor mounting point?
:S
Putting all your cards on the table is sometimes the best option if you need help.
Well, it appears the exhaust is a bit too short for the car. Its an SRN109 exhaust, but it sticks out a little too far at the rear and it sags at the cat by about half an inch too far.
I want to fit the decat as it both straightens out the sagging problem and allows me to seal it up and sort the blowing problem simultaneously.
But can I change the position of the mounts? Also, its an old exhaust, I think its the SRN109 prior to the latest one, without the flex in the middle. The decat is a brand new scorpion decat with a lambda port, and the sensor is stuck in the cat.
My ultimate goal: to stop the sag, and seal it up.
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