Engine stall at idle

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dfgeorge

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My truck has started stalling at idle. What happens is I stop at a junction / roundabout and the engine just stops. It doesn’t happen every time, sometimes goes for a couple of days without stopping, sometimes it stops a few times on a trip.

It generally starts up straight away afterwards and runs OK then, but wife has said she has had problems getting it to start again today.

It starts first time in the mornings.

I have seen this problem most about 5km after starting the car as a 1 off problem on a trip, but it has happened at other times. It has been doing it for about 3-4 weeks on and off now.

Car is a 2007 D40 diesel, done about 115K. I changed the fuel filter after it did it the first time (mainly because I had one and it was due).

I’m reluctant to take it to a dealer as the problem is so intermittent. Any idea's what may be causing it?
 

Old.Tony

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Try cleaning the MAFS with some electrical contact cleaner.

The MAFS (Mass Air Flow Sensor) is in the rear of the air pipe that heads towards the turbocharger's intake, a couple of centimetres out of the air filter box.

Do NOT damage, drop or use tools on the sensor. It measures both air flow and air temperature and costs $400+ to replace. Just spray it.

I may be developing the same problem with mine, although it hasn't done it back on the mainland - only in Tassie.

There might be some value in checking the air filter as well.
 

dfgeorge

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Ill pick up some contact cleaner on the way home and try cleaning the MAFS. I assume something like this is safe to spray on it.

Air filter is good, replaced about 15k ago and still looks like new, blown out backwards with an air line every couple of months. I checked it last week.
 

Old.Tony

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That should work just fine. At the worst, it'll clean the MAFS. At best, it'll also solve the problem!

Mind you, it could be something else. We haven't gone into fuel quality, intercooler/EGR leaks, fuel injectors etc. It's just that when I researched this particular problem for my own vehicle, the answer that kept cropping up was the MAFS.

Fingers crossed!
 

wanderer

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Ok I have a similar problem - nissan had 3 goes at adjusting fuel rail pressure, bull, bull.

Now idles reguarly down at 550-600rpm,

Cleaned MAF sensor - was very dirty but didn't fix.

How can I just turn up the idle higher so the car doesnt sound as if it falling apart when at the lights.

Inconsitent idle is a know problem - but my dealer is dropped on his head !

Prob going to put in a DP chip so we can turn up the idle unless someone else has any idea ?
 

Old.Tony

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Low engine idle (according to the manual) can be caused by:

* A leak in the air hose between the MAFS and the turbocharger. It's most likely the hose clamped to the turbocharger under the clamp itself. The manual suggests that you "listen for leaks".

* Bleed air from the fuel system. It's likely only going to happen if you've run out of fuel or changed the fuel filter recently, although overtightening the hose clamps can cause an unnoticeable leak on the suction side of the pump.

* Drain water from the fuel system. This is at the base of the fuel filter.

* Clean air filter

* Check that battery voltage is more than 12.13V

* Check engine compression

* Failing all the above, replace the fuel injectors

It doesn't say how to adjust the idle speed.
 

dfgeorge

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I gave the MAFS a sray and took it for a run, all OK, hofully it will stay that way.

I did switch the scangauge to show inlet air temperatue, it seemed to be a lot higher than I was expecting, sitting around 38C most of the time and up to 42C by the time I got home afer a 20 min run. Outside temperature was only 25-26C. Is this normal?

Cheers
 

Old.Tony

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Mine shows above-ambient temps as well. The air filter box and intake piping (both before and after turbocharger & intercooler) are subjected to quite a substantial amount of heat.

I wonder if we could use that thermal wrapping on them to reduce the effect.
 

dfgeorge

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I was assuming the inlet air temperature was from the temperature sensor in with the MAFS, which I expected to be within a couple of deg ambient. I guess there must be another sensor the other side of the intercooler.
 

Old.Tony

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The MAFS does measure the air inlet temp as well as flow rate. That way, the ECU knows fairly well how many molecules of air are moving past and into the engine.

There's a boost pressure sensor on the far side of the intercooler, but the intake temp is read by the MAFS. It's just so bloody hot under the bonnet that it does heat up the air a bit too much.

Plus I don't think it's 100% accurate. I figure with the temps involved, 10C or even 20C this way or that hardly makes a lot of difference.
 

dfgeorge

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that makes sense. I was out in the car first thing this morning and the inlet air temperature was only a degree or two above ambient, only started rising after about half an hour.

I guess yesterdays high temp was from the car sitting in the sun for most of the day.
 

dfgeorge

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Truck has been good for 2 weeks now, so looks like it if fixed, thanks.

Seeing it is such an easy job (remove connector and 2 screws, give it a spray, and put it back) I will add it to the major service list to keep it clean.
 

Diesel Marks

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Just staryed having the same problem.
Would go around a corner and brake and the engine would stall. mainly only happened at low revs. Familiar to a petrol engine with a vacuum leak problem.
I bought some repco contact cleaner $9 sprayed the MAFS and so far so good. I have 140k on clock and poor service history by previous owner and dusty conditions.
Next I will remove the inlet manifold as that is so sooted up its terrible.
Thanks guys and Tony
 

dfgeorge

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I had another problem with similar symptoms a few weeks back, turned out to be a split in the hand primer rubber letting air in. The mafs has been fine since I cleaned it.
 

bruntyrxd40

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:tazzy:
My truck has started stalling at idle. What happens is I stop at a junction / roundabout and the engine just stops. It doesn’t happen every time, sometimes goes for a couple of days without stopping, sometimes it stops a few times on a trip.

It generally starts up straight away afterwards and runs OK then, but wife has said she has had problems getting it to start again today.

It starts first time in the mornings.

I have seen this problem most about 5km after starting the car as a 1 off problem on a trip, but it has happened at other times. It has been doing it for about 3-4 weeks on and off now.

Car is a 2007 D40 diesel, done about 115K. I changed the fuel filter after it did it the first time (mainly because I had one and it was due).

I’m reluctant to take it to a dealer as the problem is so intermittent. Any idea's what may be causing it?
Im having the same problem with mine 2010 rx d40 turbo diesel 132000 km
had it since new,
It seems like the first port of call is to change the fuel filter especially if you have after market one fitted and according to nissan if you change your filter only use a nissan fuel filter and then according to them the fuel system needs recalibrating, now I have replaced fuel filter twice only started having this problem last 6 weeks at first a few times a week but seems to be getting worse. so Im going to bite the bullet buy a nissan one for $146 throw my $27 one away and see what happens
I took my ute to a trusted mechanic of a mate of mine he had a computer hooked up to see if codes came up but none did but it was definitely something with fuel or air mixture either to much fuel flooding system
or air censer telling computer bad things as he pointed it out on the screen fuel amounts going up and down through injectors
I thought it weird that this was happening putting it down to dirty fuel
and that may be a problem too as someone has mentioned in the forum
Ill try the filter and I will inspect contents of the filter I take off.
Ive just replaced my clutch which seems to be a week point on these 6 speed utes nissan wanted $3013 to put an after market heavy duty clutch in another mechanic wanted $2800 I got a guy in sandgate north Brisbane to do it for $2200 and he did the next day after I called him (great)
mick 0738690184

good luck regards Ian
 

Old.Tony

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You have to be really, really careful with the D40 when monitoring the fuel rail pressures closely. If you can monitor the pressures at half-second intervals or better, you WILL see variations even in a perfectly running engine.

What's happening is the ECU is enriching the mix a fraction, then leaning it off for the next cycle. This results in an average RPM variation of between 20 and 50rpm that I've noticed, which I can't pick by ear but I can sure as hell see it in my RPM graph (I use a bluetooth OBD adapter and Ian Hawkin's Torque application on my Android smartphone).

This variation is vital. The car uses this variation and looks at the response it's getting from the heated oxygen sensor in the exhaust. If the same variation appears, the HO2S is functioning and if the variations are missing, the HO2S has failed and the car is unable to add diesel to the exhaust stroke for use by the CAT or the DPF.

So don't immediately assume the variation means something is wrong - all is good.

I've experienced this problem with my own car and it disappeared after the next service. I think it must be a misplaced seal in the fuel filter allowing air to make its way in - there's a way to determine if this is the case. Let the car rest overnight and in the morning, pop the bonnet and squeeze the primer bulb. If you can squeeze it easily more than 5-6 times you probably have air in the lines and it's a good chance that it's because of the filter.
 

knackers84

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I'm going to try the contact cleaner on MAFS as my d40 has developed the same issue over the last two weeks. I'm not really keen on putting it back in the workshop mechanics as expensive in Darwin
 

KevinE

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Check the simple (common) stuff first.

How is your master cylinder performing?

There's masses of info on the net on how to check your master cylinder's performance, so I won't repeat it here. Just google it.

A failing master cylinder draws too much vacuum to the accumulator from the manifold & causes the symptoms described in the OP.

This is the number one reason that otherwise well performing engines stall at idle.
 

bods

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Suction control valve, dare I say it again, suction control valve...

That is the most common thing causing stalling on a cold motor. Short term fix is to run a can of liquimoly fuel system cleaner through it, you can get that from Supercheap, not sure if Repco and the likes have it or not.

There have been a few write ups on the forum about how to do it, but you basically run some hoses from the feed and return lines off the motor and either into a tub with the fuel system cleaner in it, or just put them straight in the can like I usually do. Run the motor at idle and various rpm while running the cleaner through it, aircon on and off it that tickles your fancy, a few full throttle and high rpm runs will help to open the injectors right up and increase the rail pressure and vary the movements of the suction control valve to give it a really good clean.

The can should last for about 15 min. Whatever you have left afterwards you can just pour into the fuel tank. Then hook the fuel lines from the tank back up and you should be good to go for a while.

The suction control valve doesn't last forever, so while cleaning it helps for a while, eventually you will have to replace it. Some people on here have had reasonable success removing the valve and rotating it over 180 degrees and reinstalling it. I haven't had to do that to mine yet, I have a D22 with around 120k km on it and have run the cleaner through 2 or 3 times. Normally before they start stalling at idle, the motor will hunt on a cold start, revs going up and down for no apparent reason, which is the suction control valve trying to regulate fuel pressure but can't react quick enough so the rpm jumps up and down a lot.

Good luck.
 

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