Fuel Injection Problems

[Andyjo]

Hi All, I'm after some advice on fuel injection issues I have with my 2012 STX 550 (V9x motor). For the past few months it occasionally went into limp mode, a restart got it running again. However the problem deteriorated and I had read changing the fuel filter could solve the problem. I changed the filter bled the air with the supplied bleeding pump and it started fine. Next day went to use the car and it failed to start, I re-bled the fuel system, got a lot of air out again but still failed to start. Each time I rebleed the fuel system I get a bunch of air coming out?? Previously I've only ever bled the system when I have changed the fuel filter with no issues, filter on, bleed the air out and away it went with no issues.

I've googled the limp mode issue and found an instance of my exact same problems but it was on the 2.5 4 cyl engine, they claimed the problem was the SCV, subsequently I've spoken with some knowledgeable folk and they said it was unlikely to be the SCV. I put my OBD2 scanner on it and got 2 errors both being P0488 which I was informed was an issue with the ERC system. I've tried the "pedal dance" ECU reset but nothing happened, no indications of anything being reset or any EML blinking activity. So I'm not sure why that didn't work?

This issue maybe be resultant from my inadvertently (brain fart!!) filling the car with unleaded. To solve that issue I drove 5 km to home then drained the fuel tank and flushed lots of diesel through the system using the bleed pump, and changed the fuel filter 3 times during the exercise (OUCH at $120 a pop!!). That was 2 years and a bunch of Kms ago and there were no immediate apparent problems.

Any ideas or experience with this sort of problem would be most welcome.

 

[Old.Tony]

P0488 - according to the Nissan manual for the V9X - is an EGR flow fault. These cars have a sensor in the EGR valve that detects the flow of EGR, and if it's not flowing when it's expected to (for instance, when one of us clever buggers go and block the EGR pipe) it triggers this error, shows the Check Engine Light - but I am not sure if it triggers limp mode (it might).

This means there may be several possibilities. The V9X is difficult to work on in this area too.

* Broken EGR tube. This would allow the exhaust gas to flow out into the engine bay instead of being pushed into the EGR valve and the intake manifold. You should be able to hear this, but look for signs of black sooty emissions from the EGR pipe.

* Blocked EGR tube. You won't see any sign of emissions from the tube, you have to remove the tube and inspect it. It may be possible to just open one end and use an inspection camera.

* Faulty EGR valve. If the valve is commanded to open and the solenoid is broken, faulty or otherwise unable to open the passageway, it will record this as a bad flow

* Poor electrical connection to the EGR valve. Could be that someone pressure-washed the engine bay (not a good thing to do). Maybe it's just a dodgy plug, I have one on my left hand tail light.

Putting petrol in and running it will - if there was ONLY petrol in the tank - not do the pump the world of good because the pump does rely on the fuel to lubricate its internals, but if there was some diesel in the tank you may have been lucky.

I'd suggest a thorough inspection of the EGR system before fretting about the pump.

 

[Andyjo]

P0488 - according to the Nissan manual for the V9X - is an EGR flow fault. These cars have a sensor in the EGR valve that detects the flow of EGR, and if it's not flowing when it's expected to (for instance, when one of us clever buggers go and block the EGR pipe) it triggers this error, shows the Check Engine Light - but I am not sure if it triggers limp mode (it might).

This means there may be several possibilities. The V9X is difficult to work on in this area too.

* Broken EGR tube. This would allow the exhaust gas to flow out into the engine bay instead of being pushed into the EGR valve and the intake manifold. You should be able to hear this, but look for signs of black sooty emissions from the EGR pipe.

* Blocked EGR tube. You won't see any sign of emissions from the tube, you have to remove the tube and inspect it. It may be possible to just open one end and use an inspection camera.

* Faulty EGR valve. If the valve is commanded to open and the solenoid is broken, faulty or otherwise unable to open the passageway, it will record this as a bad flow

* Poor electrical connection to the EGR valve. Could be that someone pressure-washed the engine bay (not a good thing to do). Maybe it's just a dodgy plug, I have one on my left hand tail light.

Putting petrol in and running it will - if there was ONLY petrol in the tank - not do the pump the world of good because the pump does rely on the fuel to lubricate its internals, but if there was some diesel in the tank you may have been lucky.

I'd suggest a thorough inspection of the EGR system before fretting about the pump.

Thanks for your input, on the the petrol fill it was around 30% petrol and that was a few years ago now.
I've looked over the EGR piping etc and there is no sign of leaks or problems and I've not blanked the EGR off.
I need to find out why I'm getting air in the fuel system. I bleed it try to start, no joy, I rebleed and its got a guts full of air again? Most curious! I'll get it on the hoist and check all the fuel lines for starters. It makes no sense, ran OK (with occassional limp mode) with no issues, changed the fuel filter and started with no issues, next day nada. Gotta be a cracked line or something similar that is allowing air into the system.

 

[Old.Tony]

Pay particular attention to the primer bulb. Oversqueezing this should make the leak more obvious because normally that part of the fuel system is in low pressure, so diesel won't go out a small gap, but air will easily come in.

 

[landmannnn]

Thanks for your input, on the the petrol fill it was around 30% petrol and that was a few years ago now.
I've looked over the EGR piping etc and there is no sign of leaks or problems and I've not blanked the EGR off.
I need to find out why I'm getting air in the fuel system. I bleed it try to start, no joy, I rebleed and its got a guts full of air again? Most curious! I'll get it on the hoist and check all the fuel lines for starters. It makes no sense, ran OK (with occassional limp mode) with no issues, changed the fuel filter and started with no issues, next day nada. Gotta be a cracked line or something similar that is allowing air into the system.

Since the only change was the fuel filter, did you clip the hoses on properly?

 

[Andyjo]

Since the only change was the fuel filter, did you clip the hoses on properly?

Hmmm, probably due the "richard cranium" award. Hose clips where fine but close inspection of the hoses to n from the filter revealed cracks.....
Off to the shops to purchase new hoses.

 

[Andyjo]

Well, hoses were not the source of the air, that remains a mystery. Its off to the Nissan dealers today, not my first choice of repairer but the only one who could do it on short notice. So I'll see what they come up with....

 

[Andyjo]

The plot thickens, nissan have had the vehicle for 2 days now and still can't get it to start which doesn't provide much confidence....

 

[[email protected]]

not sure if this helps,if the fuel is reaching injectors with pressure its could be camshaft sensor . cranc sensor, (timing ) , fragmented teeth locking the flap closed in throttle body upsetting air ratio.. although i think that when computer registers a fault it turns off fuel. happenned to me when i had a major injector seal leak, also with faulty camshaft sensor

 

[Andyjo]

Hi All, well my engine problem continues but with new developments. When cold starting the engine idles okay but when you press the accelerator it hunts and misses, with the car in neutral revving it the problem clears and thus far the car runs fine for the rest of the journey. There has been a few occasions when its happened out of the blue when stopped at lights or roundabout, again after some revving it clears. When this last happened I plugged in my OBD2 scanner and there were no error codes and subsequent scans have thrown no errors. Its almost as though the fuel drains back and it gets a guts full of air and once cleared it runs fine. It has a half tank of juice at present and the problem occurs more frequently, so I'll fill it and see if the occurrence is less frequent.

The car has a long range tank fitted and for quite a while now when I fill the tank, for the first 20 or so Ks there is a diesel leak from around the top of the tank area which appears as a drip on the floor at the rear LHS. Its caused no drama apart from dieselly mud around the LH underside of the vehicle so I've just lived with it, however I'm now leaning toward that being the source of my problem, although the leak has been around for a lot longer than the air in fuel problem. I was pretty convinced that the SCV was the culprit but the lack of error codes (including the EGR code which nissan wanted $1700 to repair) makes me rethink that assumption.

So has anybody else had issues with air entering the fuel system from either the fuel lines of fuel tank?

In regard to limp mode, am I correct in thinking that once in limp mode you have to stop and restart the engine to clear it? Or does it clear itself under the right circumstances?

 

[Old.Tony]

It usually occurs around the fuel filter, which is normally in a low-pressure state (the fuel is sucked through it, not pumped through it). Four possibilities come to mind:

1) Primer bulb deteriorating.

2) Cracked fuel hoses.

3) Overtighted clamps on the hoses causing pinching of the hose.

4) Water sensor not located properly in filter, or the seal has been dislodged.

The way to find any or all of these is to start using the primer bulb until it gets firm, but then continue squeezing it. This will create an overpressure in that part of the fuel system forcing diesel fuel out of the leak, allowing you to find it.

 

[Adhaul]

Hi All, well my engine problem continues but with new developments. When cold starting the engine idles okay but when you press the accelerator it hunts and misses, with the car in neutral revving it the problem clears and thus far the car runs fine for the rest of the journey. There has been a few occasions when its happened out of the blue when stopped at lights or roundabout, again after some revving it clears. When this last happened I plugged in my OBD2 scanner and there were no error codes and subsequent scans have thrown no errors. Its almost as though the fuel drains back and it gets a guts full of air and once cleared it runs fine. It has a half tank of juice at present and the problem occurs more frequently, so I'll fill it and see if the occurrence is less frequent.

The car has a long range tank fitted and for quite a while now when I fill the tank, for the first 20 or so Ks there is a diesel leak from around the top of the tank area which appears as a drip on the floor at the rear LHS. Its caused no drama apart from dieselly mud around the LH underside of the vehicle so I've just lived with it, however I'm now leaning toward that being the source of my problem, although the leak has been around for a lot longer than the air in fuel problem. I was pretty convinced that the SCV was the culprit but the lack of error codes (including the EGR code which nissan wanted $1700 to repair) makes me rethink that assumption.

So has anybody else had issues with air entering the fuel system from either the fuel lines of fuel tank?

In regard to limp mode, am I correct in thinking that once in limp mode you have to stop and restart the engine to clear it? Or does it clear itself under the right circumstances?

It looks like you and I have similar issues, I have been advised on another forum that the 550 can be a "bastard" to bleed, the only way I have managed to bleed it so far and I still don't have my engine running, is to prime it and then individually bleed at the injectors, you need some one to crank the engine for you. (See my thread "engine failure 550stx") To help with your diesel/petrol experience you shouldn't have any worries with the flushing you did, better than you would have got if it went to a dealer - PS I have NO trust in dealers as they are generally young fitters and have no real diagnostic knowledge, they do have support at Nissan but that seems to be pretty useless unless it's a current model in production. Now I do have a lot of EGR experience and it would seem that the EGR requires replacement about every 80,000 km, (possible inbuilt obsolescence, which I thought was illegal) no matter what I've done, including having the EGR locked out of operation with a reprogrammed "chip" unless you replace it you will continue to be forced into a limp home mode at any time without warning (which can be dangerous) I'm on my 3rd at 220,000km and it's a bitch to replace. Ther is so much "stuff" on this engine it's ridiculous, if only we could rip it all off and reprogram the computor, it would run cooler, produce a lot more power and probably be a hell of a lot more reliable.

 

[Adhaul]

Hey Andyjo how the hell did they/you get the engine started eventually?? I'm really curious as I have a similar issue with no joy

 

[Monsta]

The car has a long range tank fitted and for quite a while now when I fill the tank, for the first 20 or so Ks there is a diesel leak from around the top of the tank area which appears as a drip on the floor at the rear LHS. Its caused no drama apart from dieselly mud around the LH underside of the vehicle so I've just lived with it, however I'm now leaning toward that being the source of my problem, although the leak has been around for a lot longer than the air in fuel problem.

I also have a long range tank, and if I fill it right to the very top of the filler pipe (instead of stopping at the automatic cutoff), then I get a drip just like you describe. It is the excess leaking out the small breather pipe which connects at the top of the filler pipe and, just as you describe, it stops after about 20 k. I can't imagine it has anything to do with your problem.

 

[Andyjo]

Monsta, thx for that, I kinda suspected it was not connected with my current issue. I've lived with the drip for quite a few years now...

Tried the car again yesterday and started fine, try to accelerate and it misses and farts about, blows heaps of white smoke, after a few minutes it cleared. But this was the worse event thus far, the car actually cut out a few times before it cleared, interestingly after it cut out is pretty much started again straight away, but continued missing and blowing smoke til it cleared. Whacked the scanner on it and no codes at all?? Then it ran fine for the rest of the day.
I reckon its air getting into the fuel system somewhere, next step will be to replace the fuel filter lines with clear plastic so I can see if there is air entering from before the filter or if the issue is between filter and pump. I also plan to install a check valve between filter and tank to see if that resolves the issue....

 

[Old.Tony]

You could also overprime the fuel system to see where the fuel leaks from. It should normally take about 4-5 squeezes before it becomes firm - just keep going and the diesel will come out of wherever you've got a leak.

 

[Adhaul]

If I am correct (I've attached a schematic drawing for guidance) there is NO check valve/backflow valve that prevents air being admitted to the system. Refer to drawing to follow my discussion - At the fuel filter supply (refer section 'A') there is a check valve that stops fuel going back to the filter, and it also provides a control so that fuel will only enter when the vacuum is applied (ie: fuel pump draws) The junction at 'B' is open and it would seem that the fuel returning to the tank provides a restriction (or maybe there is a check valve further down the line, alternatively it could empty low in the tank, providing an air lock out) When you remove the Cap, and connect the primer, there is a valve within the primer, this provides the air lock. Air is drawn out from pump supply and the injectors via the injector return lines (quite a complex web - which takes some doing) There is NO check valve or backflow valve in the connector at 'C' only the fuel temp sensor. Now from my research the most incredible thing is that the air is prevented from entering into the fuel line via the "CAP" ONLY. So, as with my bitter experience of bleeding and not starting, had I actually reinstalled the cap I would have started the engine days ago. It is now running sweet. So unless something has escaped me the CAP is a major point of concern as it does not clip down it is merely a "condom" and as it ages it becomes loose - resulting in "incoming air"
I would suggest this is where your issue is. PS I'm happy to be wrong but I've turned this system inside out literally and just couldn't believe the discovery.

 

[Old.Tony]

The system relies on the filter section of the fuel hosing to have no means of air getting in. It's like a straw (you'll need a bucket for this one). Place the straw in the water, put your finger on the top end and lift the straw up (not completely out of the water). The straw remains filled with water. Lift your finger and the water flows out quickly. The same principle applies to our fuel system - so if fuel is going back to your tank, there's a leak somewhere.

 

[Andyjo]

Tony/Adhaul, thx for your input, that's a very useful observation with the bleeder cap. I'll definitely be checking that out. The problem has deteriorated to the vehicle being unsafe to drive, it often misses badly when trying to accelerate. So took to a local injection place and they didn't even recognise there was a problem until they tried to move the vehicle while cold where it misbehaved badly. After checking out what they could no issue could be found, as a hail mary effort agreed to change the SCV or metering valve as it is called in this guise. Drove home, run well apart from while accelerating to merge on to a freeway it started missing badly, to the point I had my indicator on to head into the emergency stop lane. At the last minute it came good and drove the remaining 10 ks without incident. Car is now virtually undriveable as it is very reluctant to accelerate.

Spoke with the fuel injection guy and told him problem is now worse. After some discussion I relented and agreed to send it to Nissan for fault diagnosis and he'd repair it for half what Nissan quote. While Nissan don't have experienced people (apart from probably one bloke) they do have all the hi-tech diagnostic gear. They have had the car for two days and have now reported they can find no fault, they proposed a "suck it and see approach" which was probably gonna cost 3K for just the tear down and test process. As a guide I asked how much for a set of new injectors.... Luckily I was sitting down when I was quoted $1000 per injector plus labour!! Anyhow I spoke with the injector place bloke and he quoted around $480/injector, but there will be a bit more diagnostics done before any big buck bits are swapped out. Car is being moved to his shop tomorrow. I will definitely relay the bleeder cap information you provided, what you describe bears an uncanny resemblance to my problem. Hopefully it eventually turns out to be a cheap fix, the car is turning into a money pit and will be on the market once its all sorted. I now drive a V6 Amorok.....

Adhaul, in answer to your question on how I got it going when it had a gut full of air; sent it to Nissan, took them 3 days to get it running (probably incompetence rather than difficulty), it is as you thought and how it was done in the good ole days, gotta crack the injector lines and crank it to bleed the air out. As you rightly point out, there is so much crap on the motor I've not even dug in deep enough to find the injector lines, I presume they are under the rocker covers.... And it looks like getting them off will be a mission.

 

[Been a while]

Fit a pick up pump at the tank.. That will sort out feed, bleed problem's and cracks in lines.. I play with the zd and they are a completely different injector "thank frig,$160ea", but if yours are electronically controlled - maybe a wire breaking down or cracked?
Or it may just be a failing injector.. Sounds like she's over fueling at times, careful- they will cook a piston from that !

I feel for you man, nothing worse than having to use Nissan Stealerships for diagnostics eh
Save money and buy a scan tool or the EcuTalk scan program!

The breather on your fuel tanks should not vent to air/ground! If you are seeing fuel there's something wrong! That breather should go back to the fill pipe neck, not open to the air!