Engine limp mode issues

[Dubman]

Hi I have an issue with the motor going to Limp mode. No engine lights or warnings. I have changed the fuel rail pressure switch and the SVC, also changed fuel and air filters.
Sat at traffic lights idling ok, set off and no power. Cycle engine off and back on reset all good. Also has it coasting down hill low revs and had to cycle off and on again.
What else could be the issue?
Thanks

 

[Zephyr]

Suction control valve would have been my first thought, but you've done that so obviously not.
Can you check fuel pressure? I have a cheap OBD2 reader that shows limited live data for diesels, but does show live rail pressure for my D40.
It doesn't seem like a bad fuel pump, as it wouldn't come good after a restart, but limp mode with no lights or codes does seem like it could be a fuel supply problem.

 

[Dubman]

Swapped the SCV and re did the pedal reset, though this time i did the addtional step putting the ECU into Learn mode. It now seeems to have stopped going into low power mode.
I have noticed when accelerating i am not getting the engine picking up as well as it should considering it 2.5 Ltr. Are there any other items i need to check over?

 

[bringthenav]

Ive had this same trouble.
I cleaned my SCV few times with Turbo cleaner & Diesel cleaner in the Fuel etc. Doesnt last.
Changed it last week & did the learning pedal reset w the neg battery disconnect & put foot on brake for 30 secs trick. Truck behaving ok now, limp mode a seem gone. threw a code again few days later, blowing lot of gray brown smoke under any load.. still .. was worse before, much better power & fuel pressure under load again though, i need to do my fuel rail pressure sensor & do the ECU pedal learn again. I need a decent code reader to know wassup. I do have a few other things to tell u that helped me..

*Check All of your boost piping, i had some slight loose fittings all over pla ce, we r running 19-23psi boost constantly, it had a very positive power effect & less random limp mode causes

*Check your Fuel Filter Hose Connections r tight enough / The Air&Water Black Dial at front (My Decent i think Sakura replacement had a slight loose round black dial i noticed one arvo! I could smell fuel & there was a hint of wet diesel around there, the dial has 2 sections... the back part up against the metal waa slightly loose on mine i think, i hand tightened it ckockwise, it helped immensely with random breakdowns n limps and random loss of power after hills/Stalling. i don't mean the front part of the black dial u turn anri clockwise as u pump the primer to release diesel air and water from fuel itself.. i mean the same dial but the main bit behind it up against metal housing of fuel filter, that black plastic whole bit can come a bit loose ( i reckon air was getting in my filter fuel lines while engine running or something)

*Check Fuel Filter primer bulb.
Mine was often Soft and taking 10-12 pumps to prime up (should be semi hard all the time... that's what she said).

*I replaced my whole primer bulb with an Aftermarket one off Ebay that is more solid and thick Material & have Alloy Bsp connectors on both ends, new fuel line & actual hose clamps done up, nothing stock at all no more, i noticed my stock connectors moved a fair bit, i reckon air getting sucked in or something making me have a flaccid bulb before. Not what the missus wants i assure you! Im now rock hard all the time, havent had to check for many months.
(See my posts for one where i show the mod fitted up!)

*Get a real good code reader, mechanic mate to go over the car with a few scans, even if your not throwing codes, i was having many many limp modes with no codes for months. now even after all that, i got limp modes & sometimes recently with codes thrown which sometimes clear themself

*Another thing could be boost solenoid.
They are notorious & i replaced mine with a Tillix Valve System like Old Tony recommends & its heaps finnicky to set up, i have the optional boost spool rate restrictor Tillix recommends, it boosts great up to 23psi.. i began hacing problems and switched the restrictor part with an old manual boost controller wound closed completely.. as i was getting bad overboost & the truck spools up close to stock just a bit faster & a bit higher to a full 23, seems to eliminate a lot of the power loss. This boost on the Tillix was a bitch to sett & the restrictor bit even more so. Thinking about running a Mac E-Boost, i have heard it can be done & plug that to the stock Solenoid wiring loom. But for now i am happy & i have grear boost eliminating thar power loss you sound like your getting.

I am convinced i have more to do yet myself, but the Truck is stable and driving pretty good, making reasonable stable hill climb power, and ok on the freeway.. so for now i am happy

*Could always dump your fuel & enpty and do a full fuel tank clean (inc the pickup) and reinstall, if you did that you'll need replace fuel filter again with it to get the results.
(I cant even begin to imagine what sludge creatures lurk in my tank)

Really i dont know whats causing your issue after u did the right things, but one or more of these things i did or want to do could help or stop the problems.

Definately consult a good code reader and get mechanics to look at that if u know one or happen to be one, and keep talking here mate, let us know if u get it solved and how

 

[bringthenav]

oh about the primer bulb, i meant to say mine only needs about 4-5 pumps these days to harden, i used to stall and itd need 10-12 to harden, then stall again or limp mode next day or a week later for example. definitely had some air leak issue. gone now since i modded it fairly sure

 

[bringthenav]

Am i correct people that the Navara has a Fuel pressure reg or valve somewhere that u could ask around about (besides the fuel rail sensor) & also possibly could be an injector issue or unlikely but possibility of a fuel pump itself (i hear they rarely fail yeh)

 

[Dubman]

My Neighbour is a Mechaninc, he said he would have done all the steps i have done. We also checked the boost solenoid. I have a decent scan tool that gives me alot of data, the issue is there is not that much data coming from the ECU. I will look over your list and check what you have done to make your engine run correctly.

Thanks for the advice.

 

[bringthenav]

No worries. Yeah just getting code numbers and bugger all certain cause data doesn't tell us everything, unless the person looking at problems is a Mechanic who is a Nissan Genius having worked there, i found this when i had a Subaru i sorted out loads problems with one time, got lucky on Airtasker finding Mechanic keen to do side gigs that worked at Subaru, total genius fully fixed all engine issues i had.
Maybe try Airtasker, asking for a mechanic who has worked on Navaras alot, pref at Nissan itself.

I went for a drive today with my brand new SCV, no more limps at all & no more engine shuddering for up to 30sec i got after pulling up after going up hills. I reckon i still have a rail pressure issue, im blowing so much black brown smoke on all accel under any load
I am about to do Fuel Rail Pressure Sensor, hoping to sort that, couldn't remove it, locked in too tight, so need to go into a shop.

Go thru the list & check those codes and keep askin round, maybe try a different SCV.
I got mine for $80 i think off eBay, its working great, if it stuffs up i will buy a more expensive one but theyre not too cheap are they .

Seems weird you did the right steps to get rid of Limp Mode & still got it. Always install SCV the correct way up is a very important thing.

It doesn't work right apparently if fitted upside down, and both sides look the same, except the sensor plug. Plug should be at bottom when installed. The O-rings r sensitive too