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How to investigate and fix engine running issues

683K views 50 replies 20 participants last post by  jessjhall121 
#1 · (Edited by Moderator)
Before you Start
OK, so you have a problem with your truck. It is tempting to search the internet for those exact symptoms and buy a new part to fix the problem. This might work, but before you start experience tells us that there are a few simple steps that will cure most of the issues you might be having and if not give you a good baseline to progress from.

The YD25 engine
The YD25 engine fitted to the D40 Navara, is powerful and efficient for its size, however, to enable it to do so, it has a sophisticated fuelling system with sensors monitoring performance and demands. This means that if the ECU does not see the feedback from one of the sensors it expects to see, the engine will drop into safe running or ‘Limp mode. (A severe reduction in power to prevent engine damage)

Sometimes (but not always), this limp mode will be accompanied by the amber ‘Check engine warning light’ coming on. Turning the engine off and restarting will normally get it out of limp mode but the reason for the limp mode still needs to be researched at a later time.

Occasionally the engine will suffer misfires, stalling, poor performance, or excessive smoking without falling into limp mode or lighting the check engine light.

This guide has been written using information gathered from the forum, and the source can be found using the search function.

So to start, try the following in order; it will cost you a lot less than a diagnostic assessment from Mr. Nissan and might actually fix the problem.


Change the fuel filter
The fuel filter is easily contaminated (after a dirty or water-contaminated fuel fill) and as a result, will flow a lot less fuel than the engine demands. There have been problems with cheaper aftermarket filters not working correctly, so our advice is to use a genuine Nissan item or a top-quality equivalent. The canister-type filter used on the 2007 onwards D40, has a Tee piece connector on top with a sealing ring. The cheaper filters do not come with this fitted and can allow air into the fuel system. Genuine part No.16400EC00A for the canister (Euro4) type.

Check, and possibly change the air filter
The air filter can be blocked by dust, leaves, and even water. If in doubt, change it. If it is water-damaged tell us!

Clean the MAF.
This is also known as the airflow sensor, it is mounted just after the air filter and can become dirty especially if an oiled aftermarket air filter is used.



Try resetting the ECU and reading any fault codes
This is a way of reading the fault codes stored in the vehicle's ECU without using an aftermarket code reader. It also resets the ECU to factory settings so may help with ‘Injector rattle’, excessive smoke, etc.

Turn the ignition on so all dash lights come on.

Wait 3 seconds

PUMP the accelerator pedal 5 times within 5 seconds...

with the foot now OFF accelerator, wait 7 seconds...

After 7 seconds press and hold down the accelerator pedal for 10 seconds...

After 10 seconds, the Engine Management Light will start to flash, at this point, remove the foot from the accelerator.

The Navara is now in diagnostic mode, so let the EML flash for a bit.

Fault codes are 4-digit numbers. (i.e. 0246) The EML light flashes in a sequence of 4 blocks of up to ten flashes. The first number is dictated by the slow flashes and the next three by the fast flashes. For example, 0246 would be ---------- .. …. ……

Take your time and read the flashes a couple of times to be sure.

Press and hold the accelerator pedal down for more than 10 seconds..this will then reset ECU and fuel pump, etc......and put them into learning mode. You’ve now finished.


As an alternative to reading the fault codes using this method, you can use a code reader. These are readily and cheaply available and you can even get an app for your mobile phone to do this. (This does not reset the ECU, though).

If you get a fault code, tell us what you get.

Be aware that fault codes are not always a true reflection of what the problem is, although they should give us a good starting point.

Consider fitting a blank to your EGR valve.
The Exhaust Gas Recirculation (EGR) valve is an emissions control device and should not be tampered with, however, there is no reason why you should not fit a blank as a temporary measure to see if that solves your problem. The blank piece fits in the supply pipe and costs no more than £5 from eBay.

It has been pointed out that some 190 models can occasionally throw up a fault code (P0401) relating to the fitment of the blank. There are no other symptoms attached, and it is easily cured by an ECU reset.



Do another ECU reset. Possibly a 'Hard reset.'

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#3 ·
Thanks Paul,

I was thinking we needed a post like this to direct folk to, to get them started.

At the end of the day though it is a summary of advice using a collection of information gathered from here, a lot of very talented members have been responsible over the years for the quality of this information. :bowdown1 :bowdown1

I've got another couple of help guides in the pipeline..... :thumbright:
 
#8 ·
smish46 said:
That's a top guide and one that might be useful when looking at potential trucks to buy. Just out of interest, what is the mobile app you mentioned in the guide and is this to be used in conjunction with a bluetooth OBD adapter?
Yup, the one I use is called Torque (for android), it needs a bluetooth adapter. Discussed here;

viewtopic.php?f=121&t=90513

and here;

viewtopic.php?f=44&t=103434&hilit=torque
 
#11 ·
ha ha ha .... compliment mate

we've a saying in our house now...... whenever we are doing something around the house or out in the nav, and we are unsure of something, she always looks up and say's " keith will know" ha ha...

fountain of knowledge mate, we always appreciate your input, as I'm sure many on here do as well
 
#12 ·
lookskyward1 said:
The press and hold the acclerator pedel down for more than 10 seconds..this will then reset ECU and fuel pump etc......and put them into learning mode. You’ve now finished.
This was something that I wondered when i used to do the pedal dance but always forgot to ask, is there any indication that the ECU and fuel pump have been put into learning mode? Does a light come on/turn off? Does it stop flashing the engine codes or do you just have to assume that it has done it?

Also, agree with Danny above...you're a legend! Never met you but i'm sure you've deserved a pint or two from me! :D
 
#13 ·
Hi all, that is top info and nice and clear. After performing a timing chain repair I would just like to add a bit about the ERG blanking. Due to the amount of carbon contaminated thick oily mess heald within my inlet manifold blanking is only half the job. To get a positive result and allow the cylinders to breath uniformly can I suggest that the inlet manifold needs to be removed and cleaned throughly. My no1 cylinder was almost completely blocked! How and fuel was being used efficiently is a wonder. There was so much crud also heald around the ports into the head the air flow to at least the first two cylinders would have been drastically reduced causing chocking and no doubt a reduction in power. Yes it will take a couple of hours but well worth it from what I saw in mine. I hope this helps as the ERG blaning is the start, not the cure.
 
#15 ·
Thanks Keith - plenty to think about there, and when I get a moment I will go through the list. By "waste gate" I meant EGR, which I thought was doing the same thing as a waste gate. Shows how much I know about automotive engineering - a tad different from the marine version...
I guess you consider I should blank it off, even though I am in a hot country? I'm not bothered about emissions in this country providing the truck doesn't smoke.

Stephen
 
#17 ·
Hi Geoff, I've moved your post to the guide in the D40 section.

Fault codes only come in four digits. It may be that there is more than one code coming up ( two groups of four flashes). Have another go if not try a code reader.

Do you have any symptoms other than the fault code(s)?
 
#18 ·
Morning,
There were definitely five groups in the cycle. Is zero always represented by 10 long dashes or can it be either dashes or dots, with the long dashes simply representing the first digit in the string? First indication of a problem was a Limp Mode experience three weeks ago which I did not understand but fluked a fix by switching engine off.

Yesterday, I removed, inspected, cleaned and replaced the mass airflow sensor as detailed in this stream. It was really quite clean. I was hopeful that this would do the trick. Sadly, the light came back on again today and I did the peddle dance again to reset the system. I have a code reader on the way.
 
#20 ·
Hi guys

Just like to thank you keith for such a great write up as today my malfunction light cane on and when ive followed these steps i had the code 0409 flash. It relates to the EGR so i presume some dirty emisions went through it or it is just got to the point were the dirt has built up a lot..
i have reset it and has now turned off.. so i will see if it comes back.. and if it does i will consider blanking it off. Do you guys agree? And also by blanking it off does it not cause the light to come on again if it doesnt detect flow or air/gases??

Cheers:wink2:
 
#21 ·
Thanks Ben

The guide was a written to collate all the methods we had found to work well with the D40, a lot of clever people were involved. :bowdown1

It will be well worth blanking your EGR valve but it would be worth giving it a clean beforehand. If the code comes back after that unfortunatly you will have to splash out for a new EGR valve.

A blank will not cause a fault code on your 07. :thumbright:
 
#22 ·
Well i do appreciate how helpfull everybody is on here so thanks to everyone on here your all great.

So if the light comes back on keith, and the valve is most probably broken, would blanking it off but leaving the faulty valve on keep the light from coming on? or would i have to replace it anyway?
And what is the best way to clean it? Is it a very delicate procedure or is it as simple as cleaning it with some clean rags and elbow grease? Lol
 
#23 ·
The EGR valve sends and receives electrical messages between itself and the ECU. The fault code is caused because it's not performing as expected, sometimes cleaning fixes it, but some valves are too far gone and need replacement.

Cleaning it will involve a bit of solvent (I like paraffin) as well as some rags and elbow grease. They do get gummed up with carbon and oily deposits.

All the blank does is stop the flow of exhaust gasses into the intake, reducing the chances of future failure due to carbon deposits..
 
#31 · (Edited by Moderator)
So... the light has come back on... im deffinately going to have to take it off and give it a clean.. do you guys recomend me cleaning it first and putting it back on and then when i next have the chance and time, blank it off? And also what is the besat way of cleaning it? Taking it off completely or in situ? Also i know keith you mentioned parafin but is there anything in a spray bottle like wd40 type thing that is good to spray on and wipe with rags?
 
#32 ·
It is worth removing to clean it, this should help: http://www.nissan-navara.net/45-d40-technical-library/49194-remove-egr-valve.html

Paraffin is my favourite (cheap de-greaser)dispensed from a wee garden spray bottle but any solvent such as brake cleaner works just as well. It will be a messy job so have plenty of rags handy.

Blank it once you put it back but if the light comes on again think about a new valve.
 
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