Intermittent loss of acceleration

[Legalalien]

Hello,

I have a 2014 Spanish built D40 manual with around 140k km on the clock.

Around Christmas time I started noticing an issue with an apparent loss of acceleration which appeared to occur at 85/90km+ and more likely when going uphill. For example it happened a few times when dropping down a gear, pulling out to overtake on the highway and putting my foot down. Around the 100km/h point there wasn’t anymore except a minor surging feeling. People who have been behind me at these times have said there appeared to be some slight black smoke also but not enough to notice in the mirrors.

I took it to where the car is normally serviced and no error codes came up and nothing looked unusual. They suggested it could be the EGR as a starting point but there were no guarantees and my pockets are endlessly deep. Should say there have been now warning lights on the dash.

My knowledge isn’t strong but after some advice I’ve put some injector cleaner through the car and for a couple of months I’d say it seemed to come good although this may have been coincidence.

Until today when it did it multiple times on 20 minute journey to work.

I do have MAFS cleaner but haven’t used it yet, is this worth a try?

Having read a few other posts the Suction Air Valve (SUV) comes up a bit. The problems related to this sound similar but not exactly the same as the issue only seems to be at relatively high speed when trying to accelerate in say 4th gear or above.

Any advice would be greatly appreciated even to try and diagnose if not fix.

Thanks!

 

[Old.Tony]

It does sound like the Suction Control Valve is playing up a little, but it could also be the boost control too. Let's try to spend money only where it's needed!

First thing I'd suggest is that the MAFS is unlikely to be the culprit but cleaning it can't hurt - well, okay, let's be realistic - stopping the car every 100 metres and cleaning the MAFS is going to get old really quickly. Even every 20,000km is a bit of overkill but at least it's more sensible!

I'd firstly go get a Bluetooth ELM327 OBD2 dongle and an Android app called 'Torque' which will allow you to monitor the boost pressure. I use a digital output on mine, but I'd suggest if you're trying to monitor sudden boost losses, use a real-time graph instead (when you long-press on the background and 'Add Display' you'll see 'Graph' as an option).

That will give you an idea if it's the turbocharger that's either stalling or losing control (actuator fault). While it's a more serious expenditure to buy a turbo, you'd kick me if I had you spend $200 on an SCV only to find that wasn't the solution.

Of course, if the turbo doesn't drop off dramatically when this power loss occurs, it's likely to be the SCV (boost might drop a little, but not a lot). Try driving with the fuel cap quite loose - if the car doesn't do it at all, it's most likely the SCV.

 

[Legalalien]

Thanks so much for the great advice. I’ve ordered a Bluetooth dongle and will get on with that when it arrives. I don’t have an android device but found one that works with iOS and android. It looks like there are similar apps that will do the same thing but if not I can borrow an android device. I’ll let you know how I go.

 

[Soflegee]

ive had a similair issue but at slower speeds, i noticed using better quality diesel, not supermarket diesel, and making sure the engine is full temp before hammering it has stopped it from happening. also worth putting some injector cleaner stuff in a full tank of premium too.

not sure if the same problem but though id post anyway!

 

[bringthenav]

Hello,

I have a 2014 Spanish built D40 manual with around 140k km on the clock.

Around Christmas time I started noticing an issue with an apparent loss of acceleration which appeared to occur at 85/90km+ and more likely when going uphill. For example it happened a few times when dropping down a gear, pulling out to overtake on the highway and putting my foot down. Around the 100km/h point there wasn’t anymore except a minor surging feeling. People who have been behind me at these times have said there appeared to be some slight black smoke also but not enough to notice in the mirrors.

I took it to where the car is normally serviced and no error codes came up and nothing looked unusual. They suggested it could be the EGR as a starting point but there were no guarantees and my pockets are endlessly deep. Should say there have been now warning lights on the dash.

My knowledge isn’t strong but after some advice I’ve put some injector cleaner through the car and for a couple of months I’d say it seemed to come good although this may have been coincidence.

Until today when it did it multiple times on 20 minute journey to work.

I do have MAFS cleaner but haven’t used it yet, is this worth a try?

Having read a few other posts the Suction Air Valve (SUV) comes up a bit. The problems related to this sound similar but not exactly the same as the issue only seems to be at relatively high speed when trying to accelerate in say 4th gear or above.

Any advice would be greatly appreciated even to try and diagnose if not fix.

Thanks!

I have the exact same issue !!
My Accel at high speeds under load eg freeway hills has improved considerably since testing an Egr Blank, fitting a catch can & fitting an i-drive thing to the throttle pedal.

But the issue remains..
Its only somewhat better.
Ive even had sudden limp modes on the freeway & am lucky i am alive!

Suspecting SCV, maybe Pressure control valve, maybe even a fuel pump.

Ive just posted myself for assistance and i'll follow this post, as its a serious issue and an important one.

I'll be stoked if we both fix this issue & then others that get it can fix theirs when it happens

 

[RobR]

You could also check the plug on the fuel rail pressure sensor, remove it, spray with contact cleaner and plug it back in. My problems started with minor starting problems and progressively got worse over time, to the point where it started doing all sorts of weird things including what you guys are experiencing. Eventually I was having to pull over at some stage every time I drove it to restart the motor or clear errors with an OBDII scanner or it would go into limp mode. After years of trouble shooting, including replacing the SCV, etc; cleaning the connections on the Fuel Pressure sensor was the fix, so simple and so cheap. What have you got to lose? Give it a go.

 

[bringthenav]

I might start with doing the scv..

Listen out for some of the more knowledgeable peoples than myselfs replies.
Im just responding as i wanna fix the same issue in my Navara,
Plus be helpful.

Ive watched a few vids on doing the Scv & a bit fiddly to get at but super simple to actually swap. Two small bolts or something.

Just make sure :
get the correct part number !!
And dont install upside down !!
(These are crucial)

After that.. if mine still giving me trouble i'll look at changing this Pressure Control Valve (which i am yet to watch vids on the install..or know anything about that part really.. but i did just hear that get mentioned in some one elses similar post..)

You could also check the plug on the fuel rail pressure sensor, remove it, spray with contact cleaner and plug it back in. My problems started with minor starting problems and progressively got worse over time, to the point where it started doing all sorts of weird things including what you guys are experiencing. Eventually I was having to pull over at some stage every time I drove it to restart the motor or clear errors with an OBDII scanner or it would go into limp mode. After years of trouble shooting, including replacing the SCV, etc; cleaning the connections on the Fuel Pressure sensor was the fix, so simple and so cheap. What have you got to lose? Give it a go.

Full on. Yeah i read before i posted someone saying the fps connector fixed similar issues. Should i spray it with maf cleaner & let it just evaporate dry?
i have a full can the cleaner..
solved for $0 & 5 minutes would be nice!

 

[RobR]

I might start with doing the scv..

Listen out for some of the more knowledgeable peoples than myselfs replies.
Im just responding as i wanna fix the same issue in my Navara,
Plus be helpful.

Ive watched a few vids on doing the Scv & a bit fiddly to get at but super simple to actually swap. Two small bolts or something.

Just make sure :
get the correct part number !!
And dont install upside down !!
(These are crucial)

After that.. if mine still giving me trouble i'll look at changing this Pressure Control Valve (which i am yet to watch vids on the install..or know anything about that part really.. but i did just hear that get mentioned in some one elses similar post..)

Full on. Yeah i read before i posted someone saying the fps connector fixed similar issues. Should i spray it with maf cleaner & let it just evaporate dry?
i have a full can the cleaner..
solved for $0 & 5 minutes would be nice!

Yeah MAF cleaner will do the trick.

 

[bringthenav]

This hasn't been done yet, as i haven't had much time.
The trucks been going okay.

The fuel sys issue still there after going up large hills then cominv to a stop, some shudder and lack of fuel for a minute until it catches up..
or i juice up the pedal before moving off.
While busy i have been
*Keeping the tank full .. to stop from getting to the fuel light coming on
*Used some Lucas injector cleaner when filling up.
Seems to like both of these.

Will do the connector today

 

[Soflegee]

I have the exact same issue !!
My Accel at high speeds under load eg freeway hills has improved considerably since testing an Egr Blank, fitting a catch can & fitting an i-drive thing to the throttle pedal.

But the issue remains..
Its only somewhat better.
Ive even had sudden limp modes on the freeway & am lucky i am alive!

Suspecting SCV, maybe Pressure control valve, maybe even a fuel pump.

Ive just posted myself for assistance and i'll follow this post, as its a serious issue and an important one.

I'll be stoked if we both fix this issue & then others that get it can fix theirs when it happens

Mines started happening again, noticed it when in low range and accelerated too quickly was first time it happened in a long time, then did it twice more after that on normal road conditions. Have noticed my fuel breather pipe is hanging down not connected, wonder if this has any input on this...

 

[bringthenav]

UPDATE: Pretty much turned out to be a 'slight' boost leak around the turbo baffle due a clamp that was on way out. I could see slight filmy oily residue on the baffle and silicon connectors.

Fit new clamps & ensure all is super tight & for now 'zero limp modes'