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Discussion Starter · #1 ·
Gents,
Anyone got some specific and detailed knowledge they are prepared to share on these please?
Basically we have 2 sensors, one pre-cat and one post cat.
Can anyone tell me please what type each one is? E.g LSF LSH LSU
TIA
 

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I've got the pre cat lambda infront of me and it's stamped 'LSF 4.2 <037>' There's a couple of numbers underneath but I'm not sure which is the part number.
My replacement is made by FAE part number 77206.

You getting a new one to extend?

HTH,
 

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Discussion Starter · #3 · (Edited)
Thanks mate, very helpful. I'm just thinking through which way to go and what happens during the mapping process. I'm now a little put off by these new MOT rules about the standard cat gavin to be in place.
If there's any data out there on the post cat one i'd like to hear about it to but I suspect it must be an LSH as they will work in conjunction with each other.
Ta.
 

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I'm now a little put off by these new MOT rules about the standard cat gavin to be in place.
I thought this was allready the case? My MOT is due January so I'll get it on after this which will leave me 12 months to decide which way to go and I can see If anyone else has problems with MOT's. Remember the cat can't really be seen without some investigation. Just find a slack tester or get it MOT'd last thing on a friday ;)

Can't help with the post cat lambda but I'm seriously considering just spacing it off and running it as is.
 

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Discussion Starter · #5 ·
Not sure tbh. I though that too but then there's a bit more to it than just that.
Hypothetically, if you space the sensor out so it becomes fooled then what affect does this have on the fuelling? Duff info = duff fuelling????
If you ran your RSTuner can you monitor AFR? I.e can you read the lambda figures?
 

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Think I can read the lambda voltages but there isn't a specific AFR parameter. Can high speed AFR be calculated from these? AFAIK the post cat lambda is only used for cat warm up and to check the imissions are ok. It's the pre cat lambda that adjusts fueling and trims etc.
 

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Discussion Starter · #7 ·
Yes they can be calculated.
So that again fit's my theory, the second post cat sensor must be an LSH. The pre-cat one will only adjust fuelling once it's hot though, that's why the other one is heated otherwise you have no control under EGTs of 350 deg c. I'm still wondering what happens during mapping.
 

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Off topic but What's the calculation so I can check mine?

If post cat lambda is only used to check the cat is working then spacing it shouldn't be a problem surely?
 

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Discussion Starter · #9 ·
Is the voltage read off the pre or post cat one? Or both for the high speed AFR?
The second sensor isn't just used for cat management, it must control the fuelling when EGTs are sub 350C
 

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Discussion Starter · #11 ·
Hmm, maybe such specifics aren't going to get shared on the forum though? Reading that Yaris thread it looks like their pre cat one is heated, which would be better as you have full control from cold. If the first one on the Meg is an LSF there must be a strategy to cover cold running, either the ECU does it or the post cat sensor is heated and doing it.
Important to know if or when you're considering deleting one.
 

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Worth trying KTR or RST and finding out what they have to say. Paul's always willing to help from my experiance and If your still getting the decat from him I'm sure he'll be able to advise.
 
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