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Discussion Starter · #1 ·
The vehicle is a V6 Petrol SWB Shogun. I know these are thirtsty beasts but this is REALY thirsty. The exhaust also smells of unburnt petrol. On my Motorbike I can balance or syncranise my throttle bodies and "tune " the ECU in much the same way as you can change the air/fuel jet on a carb. This has helped clean up a smelly exhaust and improve fuel consumption. Is it possible to do the same thing on the V6? :beer:
 

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Discussion Starter · #2 ·
OK so I ve found out that there is only one TB - no need to sync. But there must be some one out there who has had fuel consumption problems over and above the normal thirstyness of the 3.0 V6! :grouphug:
 

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Often overfueling on modern injected engines is due to a mal-functioning O2 sensor. If the sensor does not work correctly the ECU puts into a OPEN loop mode and richens the mixture considerably. O2 sensors only last approx 80k and then start failing especially when cold. They need to get up to 600C for them to work which is why many modern sensors have heaters in them. Mitsi's do install two sensors (in front and behind the CAT) on later models but I am not sure about yours as its probably pre 96. So you would have to work out from the manual on how to check them without removal and then replace. On Other cars you just short two wires and measure the voltage from the sensor during various RPM's.

Jim
 

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Definatlly wut teh MOD said. There are upstream sensors , those are the ones before teh catalytic convertor , and downstream sensors , the ones that are after the catalytic convertor. In most cases the downstream sensors go bad , being they are heated types , most times the heater circuit malfunctions causing the sensor to work improperly. Thus telling the ECU the engine is running to lean ( most times setting an MIL of Bank 2 sensor 2 "Lean" " or a catalyst code" ) So with the sensor unable to pre heat itself it picks up low heat and tells the ECU teh engine is running to lean and the ecu adjust the fuel spray adittionaly making it run too rich. O2 sensors should be changed in pairs on Pajero's and Shogun's (rear especially) at 70,000 mile increments
 

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NipponDenso is also fairlly priced as Bosch , and also they work extremelly well and a high life on them as for its all i use on vehicle i need to change them. besides most the other electronics are ND. But all times ive seen pajero's with the code for the rear o2 sensor , they always need replasing. Thus that site explained how an O2 sensor works , a HO2S sensor as on these are diff, they have a pre heat circuit. That heats teh element most of teh time when cold and on start-up.
 

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Just to clarify O2 sensors and wiring.

Single wire = O2 output signal (voltage) (white wire)
Two wire = O2 sensor and internal ground wire reference (blue wire)
Four wire = O2, ground and heating element. (black wires)

If you buy an aftermarket sensor you will need to splice in your old plug. Not a big deal but it helps if you know what wire is what.

Jim
 

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To be totally honest i have seen people try to save a couple of dollars and use HO2S that are universal and need to be "spliced" to the original connector of the old sensor and have varied outcomes. Ive repaired ones that people have shorted the ECU , or the heating element power input and torched the wire and harness etc and it goes on, best thing is get a NipponDenso or Bosch OE replacment at yur local parts house. The job will go quicker and less headache if the wiring is correct.
 

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Fair comment but sometimes it is not that easy to find a reasonably priced OEM replacement. We run alot of Japenese imports here in NZ and generally our prices for OEM are like 4 times the equivelent generic sensors or simply can't get the correct connector. If you follow a couple of basic wiring techniques you shouldn't get wrong. Most owners in this forum are usually DYI and quite capable to repair themselves with a little guidance and save some $$ in the process.

Jim
 

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Well Cheers , hope this solves yur problem , but i was not meaning buying at the dealership. I just thought that local part houses in yur area carried direct replacments in Bosch or NipponDenso . Just asked because here yes , ive seen the model specific generics that yu have to splice the wires are no more than, hmmlets see original type frum Bosch or Nippon is about ฿3,400 , versus ฿2800 for a vehicle specific generic . Not much off in teh price gap. onlee 600 baht so . But if its hard to come by in yur area good on ya.
 

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Discussion Starter · #13 ·
Ongoing problem. Ive replaced the sensor with a patern part. I had to graft the connector on to the lead, The wire where the same colour and the business end was the same as the one I took off.

Fired up first time and ran well. Then on the return journey - having stopped for a couple of hours - the engine warning light comes on on the dash. The orange one which shows an engine block.

Manual says says there is a problem with the emission control system. I have checked all the connections on the "splice " and all are good. Ive put the old unit back in but still the **** light refuses to go out. Any Ideas? Is is safe to run like this until I solve it? HELP
 

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Have yu replaced both "downstream" sensors after the catalytic converter. Or all? Did yu get a diagnostic scan to see wut the specific of the MIL is?
 

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Discussion Starter · #15 ·
On the V6 I have ( 1996) there is only one Oxygen sensor - upstream of the CAT. This has been replaced. I have not been able to put the Car on Diagnostic test as the fault only occured late last night. Is there a way to run your own Diagnostic check?


I also changed the air filter yesterday. Could I have disturbed something?

****Sunday morning****

OK. Found that you can run your own diagnostics - if you have the right equipment. I only have a digital volt meter, not an analogue one. Is it possible to test with this?

Also - I disconnected the negative battery lead for 30 seconds - reconnected and the light went out! I ll run it today to see if the fault returns ( beasring in mind Ive re-instsalled the original Lambda sensor.
 

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Well as i kno of here all Pajeros, 3.0 and 3.5 all have 2 sensors excepy sum 1994-1996 SOCH 3.0 engines. But on all the rest i have worked on as well as uncles and brother there have been 2 upstream , both near the upper exhaust manifols and 2 after the catalytic convertors (a convertor per side) except on SWB and 3.0 SOCH . The Air Flow Meter it is hard to say , if the ducting was not tight and air was bypassing the AFM it could set off an MIL. The AFm is the onlee thing i could think of that could be disrupted when replacing the air filter.
 

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Discussion Starter · #17 ·
Thanks for your help Kit. Mine is the SWB 3.00 sohc.

I disconnected the negative battery terminal to reset the ECU and the light has remained off. I refitted the "new" sensor last night and so far the light has remained off. I did test both the new and the old units when I had them on the bench. The new one works great whereas the old one hardly registered any voltage at all. The exhaust now smells clean on tickover so I am looking forward to some half decent fuel consumption. :clap: Ill let you all know. :liebe011: :beer:
 

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Discussion Starter · #18 ·
Update - Truck is now running fine - no more smelly exhaust. Smoother and quieter at tick over. Much improved MPG. Thanks again to all who contributed. :beer:
 

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guys, sorry, maybe I'm out of topic, but has anyone removed the cat's altogether?? I have seen some options in terms of 'mini' cat's for the new downpipes.

currently got really tired hp from the dyno and such, so for the moment, i's thinkin' about the removal.

:57:
 
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