Engine stall while going down hill

[Gedsta]

Hi all
I have a 2002 STR 30 turbo diesel that on occasion stalls so far only going down hill coasting, no warning just nothing when go to accelerate, have had at auto elec he is getting no fault readings from computer , had it at injector bloke still nothing, has anyone had similar issue that could point me in right direction,

 

[tweak'e]

first suspect is fuel filter.
make sure its not sucking in air. that can cause air build up in the line and when you go around corner or uphill/downhill it pulls a load of air through and injection pump runs out of fuel.
bit of clear fuel line on and look for bubbles.

 

[Gedsta]

Hi tweak'e thanks for interest I'll give the clear line ago but she starts first kick after it stalls I thought it might struggle if it had air in line, I did put new filters last oil change about 5000ks ago!

 

[Old.Tony]

I would have thought filter too, or hoses surrounding it because the D22 doesn't have such a finicky filter like the D40.

If it's only happening on downhills ... is that because you only ever have your foot off the throttle on downhills (light throttle is NOT "no" throttle)? What happens if you idle the car, will it last 3-4 minutes?

If it's angle it's usually tank related. We've had one person report that their tank outlet had a crack in it - not big enough to let diesel leak out, but big enough for air to be sucked in. Another with the fuel pickup not in the right place (I can't remember if it had broken off or was stuck somewhere). A few had gunk on their pickups ... now that's a possibility.

If you have muck in the tank, the fuel pickup might collect the muck and temporarily choke the fuel off. When the engine stops, the muck falls away from the pickup and the car starts easily. After a bit of driving, the muck reaches the pickup again.

Got an inspection camera?

 

[Gedsta]

Hey Old Tony it is when I have my foot off accelerator and coasting down hill ,the ute idles no worries I start it every morning and then go back in side and finish getting ready before going to work maybe idling up to 5 mins and then of an arv but not so long, will talk to mechanic about the pickup in tank ,cleaning tank out and putting clear hose in line to eliminate or show air in line, I was thinking electrical some kind of sensor or regulator that might be faulty and cuts the fuel off no power to pump or something but resets when I turn ignition off and then back on if something like that exists I'm a butcher not a mechanic, I think this because the car starts no probs first kick after it happens, although hasn't happened for a week now. Thanks

 

[tweak'e]

electrically, suspects would be crank sensor. or the ecu in the injection pump. maybe TPS.

one of the things the ecu does is turn the fuel off when in overrun, ie coasting down hill. it should fire it back up when you step on the gas. it only does that when rpm is high enough.

 

[Old.Tony]

It does turn the fuel off (completely, there are no 'injector open' pulses sent although the fuel rail pressure remains at around 3500-4000psi) - I'd forgotten about that. Could something in the angle of the car cause the injector harness to earth, or disconnect? My harness doesn't move around a hell of a lot, and that's why I was thinking more fuel tank - if the car idles fine and just mismanages when it goes downhill, the two things at play are the angle in the fuel tank and the fact that the injectors cut out ... although wait a sec, they don't when the car's in neutral (clutch in) and you're coasting downhill.

Let's see if it's injector pulse/harness related - can you take it down a hill and push the clutch in while you're going down the hill? Does it stall?

 

[Gedsta]

While in traffic going down hill I've been knocking it into neutral and coasting down hill where speed allows me, then putting into gear towards bottom as before it seemed that the problem only occurred when vehicle was under load from the compression

 

[Old.Tony]

When it's under load like that, the injectors aren't opening - the ECU senses the vehicle speed, engine speed, engine load, driveline engagement etc etc and decides that it doesn't need to open the injectors. It's starting to sound like yours isn't recovering from that. Never heard of that before - have you had your ECU flashed with a performance tune, or has someone mucked about with it using an OBD writer? I'm just wondering if there's been a mistake somewhere causing the ECU to do something odd when returning from the injector-off mode.

 

[bods]

When it's under load like that, the injectors aren't opening - the ECU senses the vehicle speed, engine speed, engine load, driveline engagement etc etc and decides that it doesn't need to open the injectors. It's starting to sound like yours isn't recovering from that. Never heard of that before - have you had your ECU flashed with a performance tune, or has someone mucked about with it using an OBD writer? I'm just wondering if there's been a mistake somewhere causing the ECU to do something odd when returning from the injector-off mode.

Just to make sure you're on the right track, this is a zd30 motor. All injection is controlled from the vp44 rotary injection pump. Being direct injection, there's no control of the individual injectors. The ecu on the fuel pump should still cut fuel delivery to zero on deceleration though and as you said, it is not recovering from this. The pickup in the d22 fuel tank isn't the easiest thing to block, simply from its design, so it won't be an easy problem to diagnose...

It might be worth doing an ecu reset and a tps relearn. Disconnect the battery for a few minutes and either put your foot on the brake or turn the headlights on, with the negative terminal from the battery removed. This will drain any power left in any circuits in the ecu. After reconnecting the battery, start the motor and let it idle for about 10min, this will reset the accelerator pedal sensor (tps). Let us know how you go with that...

 

[Old.Tony]

Oh of course ... could this be another VP44 failure? Isn't there a reduced-cost replacement for the VP44?

If the reset doesn't fix it, it might be worth exploring the alternative pump.

 

[ben85]

Its a strange problem.
Mine did it twice in one day about 4 years ago and its never happened before or since.

 

[tweak'e]

mad thought.
connect a boost/vac gauge up to the engine.
i wonder if the turbo is failing and is partly seizing. on downhill with no fuel be burnt turbo speed goes way down and its stalling the turbo.
if turbo is seizing it would create vacuum in the intake. high vacuum means reduced compression and may be low enough not to ignite the fuel when the ecu turns it back on.

 

[Black Beautie]

I had the sender same problem email environment earlier this year. The clear fuel lines weren't selling pproperly so I replace then with new rubber one. Also I replaced the fuel filter with a original Nissan one. Also I drained the fuel tank & found the value in the pickup or collection cage wasn't seating probably & wasn't letting the fuel in properly.
I've had no problems since with the fuel delivery system.

 

[Gregs 2010 d40]

Hi all,
Have an issue with my d40 2010 thailand build. Issue is it stalls on cold starts.
Have replaced fuel filter with genuine one, cleaned maf sensor,replaced glow plugs, replaced scv have drained tank and cleaned inside of tank. Only use caltex vortex diesel from a truck stop. Bloody thing still stalls any suggestions what else it could be.

 

[bods]

Hi all,
Have an issue with my d40 2010 thailand build. Issue is it stalls on cold starts.
Have replaced fuel filter with genuine one, cleaned maf sensor,replaced glow plugs, replaced scv have drained tank and cleaned inside of tank. Only use caltex vortex diesel from a truck stop. Bloody thing still stalls any suggestions what else it could be.

Stretched timing chain? I'm pretty sure there has been mention on here of the thai built models shutting down on a cold start to indicate a stretched timing chain... surely someone will correct me if I'm wrong...

 

[Old.Tony]

Welcome to the forum.

It could be the timing chain sure, but it might also be the turbocharger forming too much of a restriction. The turbo needs to spin over even at idle. It's worth checking that the turbocharger spins freely.

When you replaced the glow plugs, did you check that the glow relay is feeding them power? We've had a couple of reports of the glow relay (check my garage for a pic that points to it, it's near the battery) burning itself out rather badly.

 

[Gregs 2010 d40]

Thanks guys ill check the turbo. Hopefully its not the chain

 

[Gregs 2010 d40]

Hi guys
Have checked the turbo seems fine and free flowing. Replaced the glow relay. Have had it to nissan still doesnt give any fault codes. They have no idea on what it is either. The truck has done 166 thousand ks.
Have disconected the cam sensor as well and tested. Question is if i replace th e coolant sensor would this be an advantage or just throwing money into it.

 

[Old.Tony]

Let's go through what affects cold running of the motor.

1) MAFS. You've already cleaned it, see if you can get the readout of the temperature it's providing (should be PID 010F). If it's close to ambient when the engine's cold that's good, but not definitive. Let the engine get warm (bonnet down, why not take it for a drive). In normal suburban driving the intake air temp should sit somewhere in the 50-60C range (with a snorkel, it's probably a bit higher without one). Above 80km/h it should get back down to around ambient. If your MAFS behaves like that it's probably fine, if it doesn't then it might be faulty, see if you can borrow someone's. At $400 a pop it's too much to throw on a maybe.

2) EGR valve open. Easiest fix is to block it, the 2010 Thai build shouldn't have a problem with it.

3) Excessive blow-by. Usually the result of piston rings gumming up, but sometimes also from worn bores, broken rings or misaligned ring gaps (they're not supposed to be lined up nicely!). Disconnect the PCV hose from the air intake in front of the turbocharger, block the inlet where you removed the hose and aim the hose downwards towards the ground. Now cold-start the engine and see how it performs. If it works well with the PCV disconnected, try some high-detergent oil, or oil additive (like this one from Supercheap - I don't mind Liqui-Moly products, they definitely work).

4) Air in the fuel lines. Actually common in the D40 after a fuel filter change, even by the best mechanics. They're really finicky, you have to properly align the central O-ring which has to be perfectly seated. If a little air gets in, it will make fuel flow erratic until the pump can draw the bubbles down. After an extended period of inactivity, it will be difficult to start. Solution: refit the filter paying extra attention to the pesky O-ring.

You've already checked the other stuff (SCV, CAS, fuel pickup). There's not a lot else, although checking the idle speed would be good. It's supposed to hover around 750rpm.