Limp mode without engine light illuminating

[geoffm]

Hi,
I have a standard 2012 D40 2.5L TD. Auto with 80K on the clock. Jsut last wee on open road the car lost power but was still able to drive. No engine mal function light came on. As soon as I turned the engine off & restarted it she had normal power back. However since that the car often but irregularly looses power.
I assume from what I have read on this site the car is going into limp mode.

I have tried, no fault codes, loosen the fuel cap, checked all rubber hoses, MAF, fuel filter but the fault still returns.

Is the next thing to try the SCV?
I have been quoted $700 from Nissan for a new SCV. Does that sound correct?
It seems way too expensive. What have others paid?

I have seen aftermarket SCV for $200 but Im worried that I may not get the correct SCV for my injection pump. Can anyone recomend a supplier for an SCV and provide a part number for the SCV to suit my model.

Thanks in advance for your assistance.

 

[Old.Tony]

Welcome to the forum.

Sounds like an SCV to me. This one on eBay would appear to fit yours and costs a little less than $700!!! If you have good hands (I don't, my left hand has fairly bad arthritis so I couldn't undo my own and had to pay a mechanic) it's just one electrical connector and two allen head bolts. There's no fuel under pressure or anything, just try to get the area a little clean before removing the old unit.

You could try removing yours and cleaning it (wash in petrol, rinse in fresh diesel).

 

[geoffm]

Thank you for the quick reply Old Tony. I will pull out the SCV and clean it today. How is it that the car goes into limp mode without showing the engine warning light?
One would think that when it goes into limp mode the computer would give an indication. I even hooked up to the ECM when the car was in limp mode and it did not show anything!

Nissan should update their software.

I will let you know how I go after cleaning the SCV.

Thanks for your input.

 

[geoffm]

OK. So the SCV was cleaned today. I tested the car and still it goes into limp mode. Has every one been successful by simply cleaning the SCV?

Should I purchase a new SCV or begin to search for something else that is causing the car to go into limp mode/

 

[geoffm]

My SCV is a long type. It has a number 276 11NO25206 stamped on the body. I cannot seem to find those matching numbers on any new SCV's.

Should I just buy any long SCV and fit it?

 

[bods]

Can you get hold of a scan tool or one of those bluetooth odb2 adaptors to watch the fuel rail pressure when the fault happens? I could be a faulty rail pressure sensor, dirty connection or fault in the harness. If you can check rail pressure and it isn't stable or the reading is very erratic, that could be the problem. That doesn't mean it isn't the scv that's the problem, you could also try running a can of that liquimoly diesel fuel system cleaner through and see if that helps.

 

[Old.Tony]

Cleaning the SCV isn't always going to fix it but there have been several members here who have reported that cleaning the SCV works. It's suggested because it's pretty much free, just a little time, and if it doesn't work you haven't thrown any real $ at it. Replacing the SCV ($200 or so), the injectors ($4K), fuel rail ($1K) or the fuel pump ($4K) are obviously more expensive options so we don't go there without investigating the inexpensive options.

 

[geoffm]

Hi Bods,
If it was a faulty fuel pressure switch shouldn't the Eng. light come on?

Does the scan tool measure the fuel rail pressure?

I will run a diesel cleaner through it.

Thanks for your input.

 

[geoffm]

G'day old Tony,
I purchased an SCV last night. As soon as it arrives I will fit it and see if that fixes the fault. Also I will add the diesel cleaner at the same time.
If neither of the two remedies above fix the fault what would be the next thing to check/change?

 

[bods]

It wouldn't necessarily throw the engine light. If it is giving an erratic reading, the ecu doesn't know what the fuel pressure in the rail is. Hopefully the new scv helps, normally when they start going, you get rough idle with stalling and surging under acceleration, but that doesn't mean it isn't worn out... seems a bit low km for that, but I guess it depends on the quality of fuel you are using too...

 

[Old.Tony]

There are really only two things to focus on.

1) Fuel - usually the SCV, rarely the pump or injectors. Can recall just one instance of the fuel rail pressure sensor being dodgy (Nissan advise to replace whole rail, but the FRPS is an individual component you can buy on eBay)

2) Air - can be a number of things, there's plenty going on here.

(a) Turbocharger failure - not really common, although I've replaced mine

(b) Turbocharger actuator control failure. Pre 2012 the YD25 used a vacuum controlled actuator governed by a solenoid operated at 100Hz. This solenoid is attached to the hard pipe on the front of the engine bay that passes the air through to the intercooler, physically sits roughly between the alternator and the left hand headlight. These cars also suffered (quite a bit) from vacuum hose cracking or glossing (replacement 3mm hose will cost about $20). 2012 and later models had an electronic actuator control which were the subject of a recall.

(c) Intercooler leaks, squeaks and oil - because blowby contains a small amount of oil mist from the crankcase, the oil readily condenses on cooler surfaces like the intercooler. Mine filled up - blew a bunch of oil out one day and scared the hell out of me when I'm driving along and saw a bunch of blue smoke! Cleaning the intercooler (rinse in petrol and leave to dry) worked for me. Make sure there are no oil spatter signs on any of the air pipe joins (= boost leak).

(d) Dirty MAFS can do it. The MAFS is delicate and $400 from a dealer (cheaper on eBay). I recently did a post on removal and cleaning - click here.

(e) Finally, a blockage in the air intake will do it. One user here left a rag in the turbocharger intake. One unlucky bugger couldn't figure out why his car was starving for air and took his car to Nissan, who looked at the snorkel and asked why the grille was broken. Upon inspection, they found that an owl had hit the grille and been sucked down to the elbow in the guard ... car would idle fine, but suffered under throttle use.

 

[geoffm]

old Tony mine is a 2012 model. The car was always serviced by Nissan. Shouldn't Nissan of replaced the Turbo actuator under warranty when it went in for a service?

 

[Old.Tony]

Yes they should have and it's probably been done. Doesn't mean the new component cannot fail - but it does mean that it's less likely. I've not heard of any problems with the new electronic actuators.

 

[geoffm]

Hi Old Tony, Thanks for the reply.
Judging by your earlier list it seems most likely that the next step is to replace the SCV. Hopefully I will receive the new SCV today and have it replaced tomorrow.
I must admit that I am getting extremely frustrated with all of this trail and error method of repair It has been 10 days now since the fault surfaced and I am concerned that if it is not the SCV. then this matter could drag on for another 2 weeks.
In this modern day and age, I cannot believe that the the on board electronics is so poor when it comes to diagnostics of a fault. EG. if the system goes into limp mode the ECU. should indicate that it is in Limp and why it went into Limp. I am very disappointed in Nissan but I imagine that all manufacturers are similar.
If it wasn't for this forum and everyone's assistance I would stuck with Nissan service and we all know what that would mean. Big bucks, frustration and time wasted.
Like many on here I need the car for work and I cannot afford this down time and the consumption of time to try and find a fault that is intermittent.

Don't get me wrong I totally appreciate everybody's help & thank you and to all on this forum. The mystery continues.

 

[jonney]

unfortunetly when the ECU doesn,t pick up a fault in the system it comes down to a process of elimination. i once had a vehicle [ mistubishi ] that broke down on me and there wasn,t a fault code picked up so what the service dealers did , they had to go through this elimination process until the right part was found to fix thie issue. when these service guys open a part package they say they have to use it then and there as they can,t put it back on the shelf, this can end up being very costly if they start at the wrong end.
fingers crossed for you geoffm that your needed part is the SCV. i bet it is your problem.

 

[geoffm]

Thanks Jonney.
The new SCV did not arrive today. Another day wasted. So frustrating. What ever happened to the good old days when you could fault find a car easily within the same day.

 

[jonney]

yes i know exactly what your talking about. i used to be a mechanic in the 70,s working on and owning the good old cars that are now worth a fortune i might add, everything was so simple with those cars / engines. the only thing that was electronic was an aftermarket ignition coil then came the pointless electronic ignition units. unfortunetly those days have long gone so we now get what the experts or should i say eggsquirts give us, which is a car full of wires and pc boards.

 

[Old.Tony]

In the old days, you had a mechanical fuel pump with a mechanical injector and you had worries like a leaking diaphragm in the fuel pump (like on a 1950's tractor that I worked on) - pretty easy to spot, really. Our engines are much more sophisticated and produce a lot more power for their capacity. The price is complexity and diagnosis.

Textual diagnosis isn't always easy. There are a lot of experienced people on this forum (and others) that share their knowledge or just their ability to find answers in Google, Wiki or the electronic service manuals that can be obtained through various means (not entirely legitimate, because for whatever reason, Nissan doesn't want us to have them). I take my hat off to all of them, because they contribute their time and effort freely and have helped me tremendously in the past.

 

[geoffm]

Hi Guys, Today i received the new SCv. it is a genuine Nissan P/N. A6860AW42B. Long SCV. The Ebay supplier even contacted me to double check that I was ordering the correct part.
How can Nissan justify a quote of $700 for the same part that I purchased for $200. RIP OFF!

Because my time is short I will get my mechanic to put the new SCV. in. I have my fingers crossed because this Sat. I have to do a trip to Lithgow. I'd hate to do that trip in limp!

I will report back after testing.

 

[geoffm]

HELP.
The new SCV fitted today. The fault remains. I'm at a total loss with this fault. No idea what to do next.
To date we have done the following.
1 - left the fuel cap loose.
2 - checked small rubber hoses for leaks.
3 - drained and cleaned the intercooler
4 - fitted a new SCV.
5 - checked turbo rotor is spinning freely
6 - fitted engine analyser several times and found NO faults.
7 - checked air intake hoses for leakage or looseness.
8 - cleaned the MAF.

Anybody got any suggestions?