Technical Lambda change

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Technical Lambda change

Dzso

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Hi folks!

I already changed my lambda probe and a smell which came from the exhaust like is something is burning….

The old probe had 4 cable 2 white 1black and 1grey the new one is the same colours. Did I put something wrong or what happening?
 
Hi folks!

I already changed my lambda probe and a smell which came from the exhaust like is something is burning….

The old probe had 4 cable 2 white 1black and 1grey the new one is the same colours. Did I put something wrong or what happening

Did you fit a brand new sensor?
What brand did you fit?
 
Yes brand new. It’s a Bosch universal
 
Yes brand new. It’s a Bosch universal
That's good news (-:
Is it a Bosch universal narrow band sensor ?
Did you change it because of the old ones age or for another reason? Any engine warning light on dash display?
 
That's good news (-:
Is it a Bosch universal narrow band sensor ?
Did you change it because of the old ones age or for another reason? Any engine warning light on dash display?
I think the consumption at the last few months was higher. And it was old.

It was the Bosch 258 986 507 BOS/ND

It’s a little bit wider I think

Nothing warning light.
 
I think the consumption at the last few months was higher. And it was old.

It was the Bosch 258 986 507 BOS/ND

It’s a little bit wider I think

Nothing warning light.
In that case if you are probably fine.
A brief slight smell could be from the new sensor getting hot for the first time.
Best wishes
Jack
 
You say the replacement is a "universal" so did it come without a connector plug so you had to cut the plug off the old one and fit it to the new universal one? I've tried this a couple of times in the past and never had much success - I only buy "big name" sensors ready fitted with connectors now. It might be interesting to graph the output and see exactly what it's doing? Multiecuscan can do this if there's someone near you who has it. The hot smell might well be due to the new sensor heating up for the first time or it may be due to the cat getting properly up to temp if the old sensor was a long way short of what it should have been doing? (I presume we are talking about the pre cat sensor here? Come to that, does the Mk1 even have a post cat sensor? - probably not)
 
Yes I cut from the old one and on put the one. I read a lot of thing how to need to do it. So I put the 2 sensor next to as and I cut the connectors off where the new one is ended. And I connected with the smart sensor together.

Yes I will have a multiecuscan. You think the program yes? What I need to see? How can I measure?

Yes it’s a pre cat sensor.
 
I think I've given myself a problem here. I'm just thinking your car probably isn't OBD2 compliant? It doesn't have a 16 pin OBD socket? Maybe it has the old 3 pin setup? My old Panda - the one shown in my avatar picture - didn't have a 16 pin socket but I didn't have MES then so never attempted to connect. With the 16 pin socket it's fairly easy. So first thing I need to know is does the car have a 16 pin connector?
 
I've just been searching the forum for info and it seems the MK1 was not OBD compliant. The oxygen sensor output could still be graphed but not, I think, using MES? You'd need something like an automotive oscilloscope.

Maybe someone who knows more about the Mk1 could join in with info here?

Just for your info these sensors behave like a wee battery. They produce voltage between around 0.1 volts and 0.9 volts depending on how much oxygen is present in the exhaust gasses going through the exhaust manifold. Rich mixture (low oxygen content) gives a higher voltage reading - tending towards the 0.9v) lean mixture (high, unburnt, oxygen content gives a low voltage reading - tending towards 0.1v) The ECU is trying to maintain a 14.7 : 1 air/fuel (by weight) mixture - at which all the hydrocarbons in the fuel are consumed by the oxygen in the air so you get a very "clean" exhaust gas with minimal pollutants. The voltage being generated by the sensor is constantly trying to trim the fuel delivered to suit the air entering the engine so you'll see it going from rich to weak to rich to weak roughly once or twice a second (at idle - does it a bit faster at higher engine speeds) you can see this displayed in graphic form via MES on your computer screen. It's very useful to be able to see this but I've only ever done this on cars with 16 pin sockets so I'm a bit lost if you can't connect.
 
I've just been searching the forum for info and it seems the MK1 was not OBD compliant. The oxygen sensor output could still be graphed but not, I think, using MES? You'd need something like an automotive oscilloscope.

Maybe someone who knows more about the Mk1 could join in with info here?

Just for your info these sensors behave like a wee battery. They produce voltage between around 0.1 volts and 0.9 volts depending on how much oxygen is present in the exhaust gasses going through the exhaust manifold. Rich mixture (low oxygen content) gives a higher voltage reading - tending towards the 0.9v) lean mixture (high, unburnt, oxygen content gives a low voltage reading - tending towards 0.1v) The ECU is trying to maintain a 14.7 : 1 air/fuel (by weight) mixture - at which all the hydrocarbons in the fuel are consumed by the oxygen in the air so you get a very "clean" exhaust gas with minimal pollutants. The voltage being generated by the sensor is constantly trying to trim the fuel delivered to suit the air entering the engine so you'll see it going from rich to weak to rich to weak roughly once or twice a second (at idle - does it a bit faster at higher engine speeds) you can see this displayed in graphic form via MES on your computer screen. It's very useful to be able to see this but I've only ever done this on cars with 16 pin sockets so I'm a bit lost if you can't connect.
I have a 3pin connector and a vag com so I can read from the ecu
 
I can see in the program the lambda probe correction and the loop open or close
 
I can see in the program the lambda probe correction and the loop open or close
That sounds great. Of course I should have said that the engine needs to be up to normal temperature before looking for the switching action as at colder temperatures the engine fueling runs from the pre-stored map in the ECU (open circuit). It will only start trimming the fueling when it goes into closed loop operation.

So are you seeing the expected switching action when in closed loop? If so then it's all looking good. When these sensors get old their output can reduce in amplitude (the voltages reduce) and they can start to switch more slowly. My old Panda switched so slowly you could actually hear the slight variation in revs as it did so!

Have you been running it much? has the hot smell gone away as might be expected if it's just the new sensor settling in?
 
That sounds great. Of course I should have said that the engine needs to be up to normal temperature before looking for the switching action as at colder temperatures the engine fueling runs from the pre-stored map in the ECU (open circuit). It will only start trimming the fueling when it goes into closed loop operation.

So are you seeing the expected switching action when in closed loop? If so then it's all looking good. When these sensors get old their output can reduce in amplitude (the voltages reduce) and they can start to switch more slowly. My old Panda switched so slowly you could actually hear the slight variation in revs as it did so!

Have you been running it much? has the hot smell gone away as might be expected if it's just the new sensor settling in?
I use every day but less then 20 km I think it’s gone. But tomorrow afternoon I will check the closing period
 
That sounds great. Of course I should have said that the engine needs to be up to normal temperature before looking for the switching action as at colder temperatures the engine fueling runs from the pre-stored map in the ECU (open circuit). It will only start trimming the fueling when it goes into closed loop operation.

So are you seeing the expected switching action when in closed loop? If so then it's all looking good. When these sensors get old their output can reduce in amplitude (the voltages reduce) and they can start to switch more slowly. My old Panda switched so slowly you could actually hear the slight variation in revs as it did so!

Have you been running it much? has the hot smell gone away as might be expected if it's just the new sensor settling in?
So I had a little time and and tried when the engine is starting to be on working temperature the sensor is open
in idle rev when I go up to 1500rpm the lambda is turning close circuit. I think everything is working fine 😊 thank you for everything 🤟
 
I have a 3pin connector and a vag com so I can read from the ecu
I don't have an obd on my citroen relay just the 2 pin terminal near the ecu how would I be best to connect to the ecu and read codes. Thanks
 
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