Navara 2010 2.5 diesel fuel consumption

[apcconstructions]

Awesome sounds good mate! Did you get stuck in limp mode or just the light? I can live with a check engine light its just limp mode that sucks!

so far only the ECL has come on - no limp mode.. Will drive a full tank now and if it goes into limp mode I can always plug the sensor back in and reset ECM.

Will let you all know if any trouble

 

[apcconstructions]

Is that with the O2 sensor unplugged or the pressure sensor unplugged? or both?

cheers cant wait to get home and try this on mine!

this is just the O2 sensor unplugged and 50mm hole punched through DPF core.

 

[Pinelli]

Interesting reading all - just come into this. Doesn't affect me as my ECU and autoelectrics works exactly as it should in a D21

A couple of comments though - I'm willing to be convinced otherwise, but I;m not sure that a multimeter would accurately read the output of an O2 sensor. The voltage on those things changes pretty fast, much faster than a typical multimeter would. I would think you really need an oscilloscope or some sort of data logging gear to really see what is going on.
Also, for anyone thinking of trying the cheap path of using a resistor or similar to trick the ECU, you might end up doing some damage. If the engine really is running lean for some reason, and you have tricked the ECU into thinking all is actually well, you won't know about it until you know about it, if you know what I mean.

ECU map seems to be the way to go. Has anyone tried an aftermarket O2 sensor though? I can't imagine there's anything special about the Nissan ones to make them worth $300.

 

[Old.Tony]

We're actually learning about this as we go, which is a fascinating experience.

An oscilloscope would be needed, because the variations (which are monitored by the ECM and that's the part that throws the CEL on us) are definitely too fast to see with a multimeter.

I'm more in favour of something that intercepts the injector signals and determines that if the cylinder is on an exhaust stroke, the signal is ignored. This allows the ECM to manage the fuel mixture AND achieve the goal of reducing fuel waste.

I'm going to look at this particular aspect, and see if there's something I can put between the injector harness and the injectors that monitors the crank angle and achieves our goal without going the full power chip route.

Another thing to consider: the off-power-stroke injector openings may be monitored as well, so that the ECM can trust that the injectors are functioning properly. We may also need to provide some sort of return signal from the injectors so that the ECM doesn't assume that they've developed a fault!

 

[Bosshog]

Boss you need one of our DPF Race pipes

Dont bugger the OEM unit. Those OEM units cost $3000 to replace ... and you may be able to sell it at a later date

Thanks I got my own DPF delete pipe made up here in Adelaide before I knew about you guys.

As for the DPF correct they are more like $4000 new from Nissan or $999.00 out of a wreck - and second hand ones are rare as DPFs in D40s and R51s are starting to fail already.

 

[Chip Tuning]

whats wrong with running with CELs. If anything is major, the car with go into limp mode. So you cannot damage anything.

 

[Bosshog]

OK I put my delete pipe back this morning and for those interested here's what our problem child looks like...

I wrapped the probe in alfoil and have it wound out so that the end of the probe is only just in the pipe and only the hole in the bottom is free to measure the oxygen content. Thats the rear temperature probe next to it.

I'll report back what happens..

BH

 

[Pinelli]

I don't think the fuel injected in the exhaust stroke is actually burnt as part of the combustion process, so it should not affect the O2 levels in the exhaust stream where hte O2 sensor is. For the small amounts sent to the CAT to be used as a reductant, it must arrive in liquid form anyway, so my guess is the injector stroke happens late in the cycle so that the combustion process doesn't ignite the raw fuel early, giving it a chance to get to the CAT.

Just reading up on the operation of a DPF, some types need to be cleaned from time to time, while others are disposable. One way of cleaning the buggers is to dump a squirt of fuel into the exhaust stroke, to burn the soot particles in the filter, or sometimes to deliberately introduce extra NOx to the system to burn them off. I reckon this is where the extra fuel injection is coming from.

I wonder if the O2 and temp/pressure senders are there to somehow measure the state of the DPF and the cleaning process, rather than the regular combustion process. Is it possible that as the DPF clogs up, pressure rises, and so the pressure sender is the one checking if an extra squirt of fuel is needed to clean it or not? Any other thoughts?

 

[Old.Tony]

Just reading up on the operation of a DPF, some types need to be cleaned from time to time, while others are disposable. One way of cleaning the buggers is to dump a squirt of fuel into the exhaust stroke, to burn the soot particles in the filter, or sometimes to deliberately introduce extra NOx to the system to burn them off. I reckon this is where the extra fuel injection is coming from.

I wonder if the O2 and temp/pressure senders are there to somehow measure the state of the DPF and the cleaning process, rather than the regular combustion process. Is it possible that as the DPF clogs up, pressure rises, and so the pressure sender is the one checking if an extra squirt of fuel is needed to clean it or not? Any other thoughts?

You're right that there is an extra squirt happening to clean the DPF. When the ECM determines that the pressure differential across the DPF is too high (there is a pressure sensor before and after the actual filter material) it decides to do a "regeneration cycle".

This regen cycle must occur while the engine temperature is normal and the RPM is 1600 or higher (equates to about 80km/h on the road in top gear). Your DPF light will NOT come on during this if it is able to conduct a regen properly - there's no need to alert the driver!

However, if it does not get the right conditions and fails several times, it will light the DPF warning light and try again. At this point even the car manual says to take it for a gentle drive at 80km/h (thus ensuring the correct engine temperature as well).

If THAT fails, the ECM forces the engine into "limp" mode. There are two ways out of that - reset the ECU and then give the ECM the conditions needed to perform a regen cycle, or take it to a dealer and get them to force a burn (about half a tank of fuel and 4 hours of hard engine operation followed by an oil + filter change and a few hundred $ handed over).

Now, back to "normal" engine operation: there are TWO kinds of squirts described for normal driving IN THE EXHAUST STROKE. One of them is designed to do the regen cycle, the other to provide reductant hydrocarbons for the CAT. "Feeding the cat" happens almost ALL the time, and this is the operation we'd like to stop.

You HAVE raised a major problem I'd overlooked. Here I am going "let's stop these exhaust stroke injector cycles" and I WANT to keep my DPF intact - if we stop the exhaust squirts altogether, it'll never do a regen and will cause huge amounts of grief not much further down the highway.

Thanks for waking me up!

It makes the thing more complicated, and moves away from the simple "ignore injector commands" - now it looks like the ECM will need some reprogramming. If it's an EEPROM holding the instructions we might be able to manage it - time to start looking into that.

Bloody complex little shit of a thing, isn't it?

 

[Bosshog]

You HAVE raised a major problem I'd overlooked. Here I am going "let's stop these exhaust stroke injector cycles" and I WANT to keep my DPF intact - if we stop the exhaust squirts altogether, it'll never do a regen and will cause huge amounts of grief not much further down the highway.

Thanks for waking me up!

It makes the thing more complicated, and moves away from the simple "ignore injector commands" - now it looks like the ECM will need some reprogramming. If it's an EEPROM holding the instructions we might be able to manage it - time to start looking into that.

Bloody complex little shit of a thing, isn't it?

Tony, correct but for those of us who have removed our DPFs we are obviously trying to stop the regen from happening and accordingly stopping the exhaust stroke diesel injections is required.

If the DPF remains in place then it is vital that a regen occurs regularly. And that the DPF gets nice and hot regularly. DPF failures are now happening all too often and in most cases the vehicle has only been driven around town and the DPF has not been getting hot enough.

 

[Old.Tony]

Tony, correct but for those of us who have removed our DPFs we are obviously trying to stop the regen from happening and accordingly stopping the exhaust stroke diesel injections is required.

If the DPF remains in place then it is vital that a regen occurs regularly. And that the DPF gets nice and hot regularly. DPF failures are now happening all too often and in most cases the vehicle has only been driven around town and the DPF has not been getting hot enough.

That's very true, and a simple and effective way to get around the whole thing is to remove the DPF which I could be tempted to do, especially if it doesn't raise emissions by too much. In other words, I'd need a chip that REDUCED the fuel going in so that it was all combusted (no rich operation).

While my vehicle's under warranty though I will not be tempting fate and making major changes like that.

With my luck, I'd change a tail light bulb for a non-Nissan one and the radiator will explode killing 57 million New Zealanders and 2 North Koreans and we'd end up in a nuclear war that resulted in a bodgey warhead landing on my house and destroy 5 roof tiles and Nissan wouldn't cover the cost of replacing the roof tiles.

 

[Bosshog]

With my luck, I'd change a tail light bulb for a non-Nissan one and the radiator will explode killing 57 million New Zealanders and 2 North Koreans and we'd end up in a nuclear war that resulted in a bodgey warhead landing on my house and destroy 5 roof tiles and Nissan wouldn't cover the cost of replacing the roof tiles.

Go on tempt fate and replace that tail light bulb...

 

[westy350]

what do you guys think about this?

My version of the o2 non fouler trick

 

[Bosshog]

what do you guys think about this?

My version of the o2 non fouler trick

That is exactly what I am trying to achieve using the alfoil. But this is better solution as it is more robust than my wire and alfoil idea.

Edit: How about I modify my delete pipe so that the O2 sensor is right out of the exhaust stream. Simple to do, just weld in long tube with a thread in the end so that the end of the probe is no where near the flow of exhaust gas. Would that work?

Stuff it I'll try it next week.

 

[westy350]

You can get these O2 SIMULATOR from ebay for about $40 i think we will need on with a 90 degree bend in it beacuse the original one is on top of the exhaust and there isnt enough room.

 

[Bosshog]

I'm willing to be convinced otherwise, but I;m not sure that a multimeter would accurately read the output of an O2 sensor. The voltage on those things changes pretty fast, much faster than a typical multimeter would. I would think you really need an oscilloscope or some sort of data logging gear to really see what is going on.
Also, for anyone thinking of trying the cheap path of using a resistor or similar to trick the ECU, you might end up doing some damage. If the engine really is running lean for some reason, and you have tricked the ECU into thinking all is actually well, you won't know about it until you know about it, if you know what I mean.

ECU map seems to be the way to go. Has anyone tried an aftermarket O2 sensor though? I can't imagine there's anything special about the Nissan ones to make them worth $300.

Yes this is exactly what is needed and they can be bought - check out this link O2 simulator

You can get these O2 SIMULATOR from ebay for about $40 i think we will need on with a 90 degree bend in it beacuse the original one is on top of the exhaust and there isnt enough room.

Nah there is heaps of space. I am going to fabricate my own and see how it goes. If no good then it is an electronic O2 simulator from the US.

Here's the extension pipe Westy is referring to.

PS - my alfoil idea failed

 

[Bosshog]

OK fabricated up the O2 sensor extension piece this morning

Fingers crossed!

 

[Old.Tony]

Good luck with that Gus, hope it works!

I've a feeling Nissan wrote some code in the ECM that monitors deliberately-induced fluctuations of the fuel mix so that it can diagnose a faulty O2 sensor. Let's see who is the cleverererest!

 

[Bosshog]

Good luck with that Gus, hope it works!

I've a feeling Nissan wrote some code in the ECM that monitors deliberately-induced fluctuations of the fuel mix so that it can diagnose a faulty O2 sensor.

NO NO Lets hope not.

 

[apcconstructions]

Good luck with that Gus, hope it works!

I've a feeling Nissan wrote some code in the ECM that monitors deliberately-induced fluctuations of the fuel mix so that it can diagnose a faulty O2 sensor. Let's see who is the cleverererest!

I agree I don't think it will work. The ECM is constantly checking values given off by the Sensor and if the values don't fall into line with what the ECM wants them to fall between then the ECM deems the sensor faulty and will disregard it. If this happens I believe that you will still gain the fuel economy but with the CEL still on. ( takes about 4 or 5 trips before the ECM flags the CEL to come on)

Once again good luck and hope it works!!