Number of O2 sensors on Gen 3's...

[RevRev]

I have an 05 NP 3.8 with some after market extractors. The extractors have a split seem on the inside of where the pipes collect together meaning a tricky job to remove and re-weld.

In comparing prices to explore just replacing the extractors completely I notice that all the ones advertised only have a single O2 sensor - yet my pipes have four. Apparently mine must have had the O2 sensor mounts custom mounted when they were installed (previous owner).

My question is: this means that at some point of the Gen3 model cycle they moved from a single O2 sensor to four? what date? If I want to go and get a simple replacement exhaust system from the wreckers how can I be sure (before sticking my head under the car) how many O2's it has?

Cheers.

[gaz1]

The change would have been made when the NM was replaced by the NP (ie from the 3.5 litre to the 3.8), I think around 2004. I fitted extractors to my 3.5 NM and there was only the single sensor. My current NT has 4 sensors, but it still retains the cast iron exhaust manifolds - there is a history of the manifolds cracking and becoming noisy, and that is the reason quite a few extractors have been fitted, they are much less expensive than new manifolds (and they make the exhaust sound much nicer, without being louder).
Hope this helps.

[RevRev]

Thanks Gaz,

I appreciate the reply. Makes sense the changeover was at the model change, but it does seem strange that the extractors being advertised for the 3.8 still only seem to have a single O2...

Presumably they are the same block hence the extractors are the same?

eg: here

[stumagoo]

Thanks Gaz,

I appreciate the reply. Makes sense the changeover was at the model change, but it does seem strange that the extractors being advertised for the 3.8 still only seem to have a single O2...

Presumably they are the same block hence the extractors are the same?

eg: here

Likely. The 3.8 went to OBD2 which had multiple O2 sensors - I have heard comments of early 3.8's having Mutt protocols but have not seen it myself, if this is the case they may only have 1 O2 sensor

[gaz1]

This is the place where I bought the Wildcat headers that I had on my NM. The link below is for their Wildcat listing for the NP (it's a different listing from the 3.5 NM), but it doesn't specify how many sensors they accommodate. There is also a separate listing for the later V6s, they have the extra cat converters required for those models and are quite a lot dearer. The company has been around for a while and were very helpful to me, maybe give them a call.

https://bestmufflers.com/bshop/index.php?id_product=1885&id_product_attribute=0&rewrite=mitsubishi-pajero-np-2003-to-2006-35ltr-38ltr-v6-wildcat-headers-wild132&controller=product

[cuckoo]

I have a 2004 3.8 np exceed and it only has 1 o2 sensor