Engine Stalling after a hill climb

[Moleface]

Hi everyone,
I am new to the forum and require help with my nissan navara. My car is a 2011 nissan navara d40 automatic thai built.

The car stalls up hill, the car goes to about 3000 rpm for a while then once the foot gets taken off the accelerator it stalls. The ignition stay on and the engine restarts upon start up.

I have replaced the fuelfilter and the fuel lines from filter to pump. I have also changed the SCV. The car has no fault codes or engine lights.

I have attached a photo of the parameters when the engine stalls.

Has anyone had this issue before?
Can anyone please help!!!

 

[Old.Tony]

The information presented is a little odd. Zero throttle, 350rpm, 100% load ... it sounds like it's in the middle of a stall at that point, so things like load% are unreliable. Other figures (apart from being archaic imperial measurements) don't seem extraordinarily out of whack - fuel rail pressure is typical for idle speed (zero throttle should result in FRP reaching a nominal idle level unless engine load falls to near zero = engine braking). As the engine is stalling the manifold pressure is just above atmospheric, and in the other two images the turbo (at idle) is producing about 2psi of boost which is a little out of the ordinary.

I can't see anything from that information that would be causing a stall, but it would be beneficial for you to examine boost pressure vs engine RPM vs throttle position and ensure that the boost is rising in response to throttle input and isn't just at max the whole time (indicating stuck vanes, or an actuator that is commanded to full at all times).

Other than that, I can only think that the system may be deprived of fuel - possibly a pickup problem in the tank? Is the fuel tank full?

 

[Moleface]

I have uploaded the video to YouTube which might be more useful.

It definitely is odd.
The fuel tank is half full, I was thinking that i might try drop the tank check the pick up and replace the fuel.

Thanks for the assist mate!

 

[Old.Tony]

It's not a supply problem from the tank - it would take several seconds of dry cranking to get the fuel up from the tank again if that was the problem. It might have picked up some crud on the fuel pickup, so a look inside the tank may not be a worthless exercise.

Under load there's a number of things that happen, I notice that your throttle level doesn't exceed 56%, which means we are in the mid-range and precisely where EGR operates. If your EGR is flooding the intake manifold it could do this (with quick-restarts like you have, because during startup the EGR valve closes). Have you blocked (or considered blocking) the EGR? The 2011 Thai build shouldn't have an EGR flow sensor to worry about, so sticking a plate in on teh EGR valve side should be all you need to do (with appropriate care to ensure no leaks by using gasket cement like Permatex Ultra Blue Sensor-Safe).

 

[Moleface]

I might rip the fuel pick up out and clean it and put fresh diesel in it either tonight or tomorrow.

I have already blocked off the egr.
Could the o2 sensor or the throttle body be playing up ?
Thanks for the help mate

 

[Old.Tony]

I can't say that the sensor or the whole throttle body isn't an issue - my own throttle body was replaced when my car was having odd issues under heavy acceleration (turned out to be the SCV on mine, but not before they'd replaced the throttle body and accelerator mechanism). Yours could be faulty, it's just not heard of very often.

It could also be an issue with the fuel rail pressure sensor (loose/dirty connections), a dirty MAFS - removing and reinserting the plugs would be the first step.

Here's something ridiculous to try, too - remove the fuel cap, then reinstall it but don't tighten it, only engage about a half-turn of thread (so it's only just holding on). Does the car still stall?

 

[Moleface]

I have tried that but it still stalls. I just cleaned the tank out and pickup out and replaced the diesel but still stalling. However when I disconnected the MAF sensor and ran it up the hill it went slow, however it did not stall. What do you think?

 

[Old.Tony]

It's odd that disconnecting the MAFS avoids the stall-on-uphill issue. I wonder if it's not so much a stall-on-uphill, but rather a stall-on-higher-load issue?

Higher loads require more air flow and higher boost. Removing the MAFS from the equation leaves the car with no idea about incoming air flow or temperature (with a small formula, knowing the rate, pressure and temperature of air means you know how many O2 molecules are at your disposal for combustion). This would make me think it's indeed your MAFS that's dirty. Cleaning it is a job that, with care, doesn't cost too much to do (and can't hurt, but heed the warnings).

Never, ever stick anything in the little hole in the end of the MAFS. This will destroy it. \

To clean it, remove it from the air piping, and use MAFS cleaner (or electrical contact cleaner, same thing) by spraying it in the little hole and allowing it to run back out. Repeat the exercise 2-3 times, it should pour out black at first, then clear up. Hold the MAFS in the open air for around a minute before reinstallation to allow the cleaner time to evaporate completely.

 

[Moleface]

I have cleaned the MAF sensor and changed the lambda sensor and still no change.
Do you think maybe fuelpump or fuel rail relief valve?
Last time it stalled it was really hard to start like the issue is getting worse

 

[Old.Tony]

I would not jump at the fuel pump straight away, they're worth about $4k from Nissan. I'd be trying other things first, and in particular putting a good fuel system cleaner through first like Liqui Moly Fuel System Treatment.

I'm still puzzled by the removal of the MAFS making it better. There's obviously something in there that I'm not making the connection with. Once the engine stalls, have you just pulled over and tried priming the fuel system with the primer bulb? Even easier still, have you tried overpriming it when the car is off? Overprimed, the fuel system should start leaking where it normally would be sucking air (eg the primer bulb). This may not allow fuel to flow back to the tank (it did on mine) depending on where the leak is. I'm wondering if under heavy load = highest fuel flow you're getting a little too much suction on the fuel system and it's drawing air instead. At worst this test will cost you a few ml of diesel, and the cheap tests are always the best!

 

[Moleface]

Yeah im still a bit confused. Does not stall with the MAF sensor unplugged. However there is a whistle sound when reving and on idle.
Could the whistle have something to do with it?

So far, I have changed the SCV, cleaned the fuel tank snd pickup with fresh diesel. Changed the fuel filters twice. Changed the fuel pressure relief valve on the common rail system and changed the throttlebody and lambda sensor with no luck.

The SCV is however a short body type. Do you know the difference between the long body type?

Does anyone know if the fuel pressure seems odd or another paremeters in the video added?