Navara d40 stx - what is this please help?

[tipsi]

Hi guys,

Im new on here. I have been having alot of dramas driving under load ie; pulling onto the highway. mainly in the higher gears (its automatic). The problem I have is more noticeable and worsened on colder mornings, sometimes its impossible to merge onto the free way with cars doing 100klm/h. If i floor it to merge onto the freeway or get up to speed, the car will not rev over 2500rpm and hesitates, rpm hesitates from 2200 to 2500 rpm and will not rev, like its cutting in and out??

And looking around and by the feel of it i though it may be a faulty boost sensor, like its reaching boost cut?? but i found this???

anyone know what it is?? its broken and looks burnt

 

[Old.Tony]

Welcome to the forum.

That's your No.1 Cylinder glow plug.

Glow plugs operate from cold until about coolant >= 85C. Once your engine is fully hot they won't operate at all. Does your car perform well then?

I've not experienced that sort of problem myself, I usually let the car warm up properly before i take it much over 2,000rpm.

However, it doesn't strike me as a typical problem caused by failing/faulty glow plugs. It could be a dirty MAFS and that's cheap to fix. Grab a can of electrical contact cleaner (Jaycar sell it for around $10, and MAFS cleaner can be bought from auto stores for $17-20 but it's the same shit). Gently and carefully remove the MAFS from the rear of the intake tube - look for it in the pic below - don't drop it, it's worth $400. Don't insert any tool into the sensor - there's a small rectangular opening in one side (facing the incoming air stream) and you need to spray the contact cleaner in there. Give it a few seconds to dry then reinstall and try the car again.

There might be other issues - turbocharger actuator (possibly just a vacuum line), air in the fuel line (possibly cracked lines/overtightened clamps around the fuel filter or a cracked/perished primer bulb).

 

[tipsi]

thanks tony. The contact is burnt and is no longer joined. So I think I am up for a set of glow plugs. I think this issue is not related to my main problem.

I have slightly over filled the oil on the last 2 changes I have done. Its breathing a bit around the intercooler hose near the throttle body. Im wondering if it breathed through my cooler pipes and over the sensor on the intercooler?? Is that sensor for boost?

The problems is more evident in higher gears especially drive and will not rev over 2500rpm.... feels like a fuel cut from overboosting.

I have checked the vaccume lines, changed fuel filter and had the injectors cleaned.

Maybe boost sensor near air box or dirty sensor on the intercooler from oil residue or soot???

its a 2007 STX automatic.

Thanks for your help and input in advance.

 

[Old.Tony]

If you're seeing oil on the charge air path (any hose, pipe or component between the turbocharger and the intake manifold) then you have a boost leak. Hoses may be split, clamps loose or overtightened, welds cracked or damaged.

Over 2500rpm you should be producing maximum boost (and the harder you plant your foot, the more the vanes are opened). Boost levels should rise up to the 19-20psi mark. If your boost is leaking through a fault in the charge air section, you won't be getting this in the intake and the car will definitely feel underpowered.

The oil is going to show you WHERE the leak is. Unless you fit a catch can, oil from the blow-by (the hose coming from the top of the rear of the engine and connecting to the air intake just in front of the turbocharger) will go through the turbo and charged air sections into the intake manifold where it's normally combusted. This is absolutely normal and working as designed.

But if you're seeing oil there, it means some of that oil vapour/air stream is escaping. Fix the leak, the oil stops, the power loss stops and you'll probably notice a new sound suddenly missing too.

 

[tipsi]

Thanks tony.

Strange thing is, ive checked for caccume leaks and split hoses or loose hoses and clamps and cant find anything. I appreciate all your help.

Weird thing is, If I free rev the car the needles revs straight to 4500-5000rpm with no issue. The moment its in gear and under load its hesitating badly at 2500rpm ,mainly under load in top gear heavy throttle. When I say hesitationg the needle will not go past 2500 rpm and cuts back to 2200, then to 2500 and back to 2200, it just pulsates and the revs will not increase but just hesitate and jump back and fro. I have to release the throttle for it to select the next gear or minimise the load so it will rev out... If I just plant the throttle and hold my foot flat it would never accelerate or go past around 60kl/h, the revs would just jump and not exceed 2500.

Could it be boost sensor, or the sensor on the side of the intercooler, or back to the boost sensor being faulty???

I have cleaned the MAF sensor and it made no difference.

If it put it in 2 or 3rd and rev it out its much happier and neally revs all the way out.

Thanks (please help)

 

[Old.Tony]

There should only be one sensor on the intercooler and that's the boost sensor, down near the outlet.

There is a problem experienced by some KC owners where in 4th gear in 4LO they get quite large fuel rail pressure variations and it MIGHT be an issue with the wiring harness to the gearbox. With that in mind, I'd have to ask if you've done any 4WDing or hit a stick on the road or anything that might have been thrown up and damaged the cables to your gearbox?

If it was just the boost sensor you'd think it would happen in any gear, although the engine load would be higher in the higher gear.

 

[tipsi]

All checked looked good. Never been off road.

Definantly feels like a boost cut, over boost, fuel cut, or some sort of Ecu override to protect something......

Could it be a faulty scv? Also looked at boost controller on intercooler and the solenoid near the air box, all visually seems ok.

 

[Leprechaun]

Definantly feels like a boost cut, over boost, fuel cut, or some sort of Ecu override to protect something......

.

Thats exactly what it is.

Clean the Maf, or even better would be to swap it with someone elses to test. Fitting a analogue boost gauge would help identify whats going on.

 

[Old.Tony]

Asking the ECU what boost it THINKS it's producing is also a good idea. If the boost sensor is inaccurate - showing twice the boost level that actually exists for instance - yes it could trigger this without needing to.

 

[tipsi]

Ok I did a self diagnostics test via the ignition and throttle pedal, and I am getting the 10 engine light light flashes, then 2-3-7...

 

[Old.Tony]

0237 in the D40 means the return signal from the boost sensor is too low. This could be a bad connection (eg unplugged, dirty, corroded) or a faulty sensor. Try cleaning it first and see how it goes. The sensor is on the side of the intercooler near the outlet (right-hand side of the car). The harness connector should be high up between the grille and the radiator on the right hand side.

 

[tipsi]

hi Tony,

I have reset the ecu and took the car for a drive, took off like a rocket ship...
no issues, then 300metres down the road, it shut down on me and the old symptoms come back....

I got back and did another self diagnostics again and I get 10 fast flashes on the ecu/ecm light???

Any clues?

 

[Old.Tony]

10 flashes is a zero, indicating no problem.

Try taking off using no more than half throttle but getting up to the same speed. Symptoms gone?

What about loosening the fuel cap a half turn and trying normal acceleration again. Any change?

If that makes a difference I'd start suspecting the suction control valve.

 

[tipsi]

Half throttle is fine... Will try fuel cap

Thanks

 

[tipsi]

well I tried the fuel cap.....

It did not fix the problem, but it certainly made a noticeable difference. My top speed was higher on the highway, as before it was limiting at 120km/h, it revved out higher 3000 rpm in top gear not 2500rpm, and also drove more like normal through the gears, although I could still feel the cutting in and out, but it was largely softened to an extent...

would these things sound like a scv?

 

[Old.Tony]

Starting to seem that way. The SCV isn't cheap but Nissan have known about failing SCVs for some time and many have been replaced under warranty. My first choice would be to talk to the dealer and see if they're willing to diagnose the SCV and see if it's faulty.