Rough idle and power loss when cold.

[mrmeme1212]

Hey brains trust. I've been having this problem for a few weeks, I've seen similar threads on here and have tried all the fixes to no avail. On cold start my 07 D40 struggles to start sometimes, it idles rough, and sometimes stalls (rarely). When taking off it has severe power loss at ~1500 rpm and 2000rpm but drives fine above that. It's almost stalled when hitting ~1500 rpm, the revs and power just drop suddenly. Once warm it drives like a dream. I've replaced the SCV and BCV, replaced vacuum hoses and fuel filter, cleaned MAF and reset the ECU (which has never thrown a fault code). I don't know what else to do, any thoughts?

 

[GunMentalGrey]

Check your vacuum hoses. Mine has had a couple split and cause issues like losing boost and difficulty starting.

Other thing to check is the primer bulb. Mine also split and allowed air into the fuel system. Which presented as a flat spot/misfire until around 2000rpm and also difficuly starting. Seems the fuel was running back to the tank and needed help to get back to the fuel rail each morning.

I found the split bulb when after a week or so of dead spot on acceleration it finally gave up and stalled one morning. Went to prime the fuel and got my hand covered in diesel.

 

[mrmeme1212]

Check your vacuum hoses. Mine has had a couple split and cause issues like losing boost and difficulty starting.

Other thing to check is the primer bulb. Mine also split and allowed air into the fuel system. Which presented as a flat spot/misfire until around 2000rpm and also difficuly starting. Seems the fuel was running back to the tank and needed help to get back to the fuel rail each morning.

I found the split bulb when after a week or so of dead spot on acceleration it finally gave up and stalled one morning. Went to prime the fuel and got my hand covered in diesel.

All the vacuum lines are new, did them last week. The old ones were pretty manky but didn't seem split. I'll check the primer bulb in there morning, cheers.

 

[mrmeme1212]

So this morning I primed the bulb twice before starting, it seemed fairly firm from the get go and it's dry. BUT the car started without any dramas and ran perfectly (aside from the noise the turbo makes but that's another kettle of fish). The problem is somewhat intermittent however and considering the bulb was already firm I'm not 100% sure that it's the problem.

 

[Old.Tony]

I'd suggest that if the bulb was already firm, there's no issue in the fuel delivery system.

Other things to check: glow plug operation (fuse, relay).

Dirty MAFS. Remove the MAFS from the air intake and spray electrical contact cleaner into the little hole in the end - NEVER insert anything at all into the hole other than liquid!

Possible sticking EGR valve - don''t bother fiddling with this thing, your 2007 won't care if the EGR is blocked. Undo the two 12mm bolts on the EGR tube where it attaches to the EGR valve (attached to the intake manifold). Remove the gasket, make a copy of this gasket using 1mm stainless steel and accidentally (haha) forget to make the big hole. Fit both the gasket and the blanking plate back where you got the gasket from using sensor-safe gasket cement (Permatex Ultra Blue is a good choice).

A failing turbocharger won't cause the car to hard-start but a blocked intercooler will. Remove the intercooler and have about a litre of unleaded petrol handy. Cup one hand on one opening, with the other opening uppermost, pour a little (100ml) petrol into the intercooler then cover the upper opening, turn the intercooler over and uncover the opening that's now at the top. Repeat this a few times to swish the fuel around, then empty into a container and repeat the whole exercise until you start to see the fuel colour in what's coming out.

See how things go with that.

 

[mrmeme1212]

I'd suggest that if the bulb was already firm, there's no issue in the fuel delivery system.

Other things to check: glow plug operation (fuse, relay).

Dirty MAFS. Remove the MAFS from the air intake and spray electrical contact cleaner into the little hole in the end - NEVER insert anything at all into the hole other than liquid!

Possible sticking EGR valve - don''t bother fiddling with this thing, your 2007 won't care if the EGR is blocked. Undo the two 12mm bolts on the EGR tube where it attaches to the EGR valve (attached to the intake manifold). Remove the gasket, make a copy of this gasket using 1mm stainless steel and accidentally (haha) forget to make the big hole. Fit both the gasket and the blanking plate back where you got the gasket from using sensor-safe gasket cement (Permatex Ultra Blue is a good choice).

A failing turbocharger won't cause the car to hard-start but a blocked intercooler will. Remove the intercooler and have about a litre of unleaded petrol handy. Cup one hand on one opening, with the other opening uppermost, pour a little (100ml) petrol into the intercooler then cover the upper opening, turn the intercooler over and uncover the opening that's now at the top. Repeat this a few times to swish the fuel around, then empty into a container and repeat the whole exercise until you start to see the fuel colour in what's coming out.

See how things go with that.

Already cleaned the MAFS, I'll get onto the EGR block and cleaning the intercooler. I've got a catch can on the way so I can do that at the same time. Cheers.

 

[mrmeme1212]

So I found one culprit, the o-ring for the water sensor in the fuel filter was split and leaking over night, because I've never really checked the engine bay after running it would have always dried up before I noticed it. Replaced and primed and it's started well for the past 2 days, weird that the bulb was still firm though. Still seems to have an intermittent flat spot ~1500 and 2000 RPM but maybe its just turbo lag and I'm noticing it more because I'm looking for it?

Also, for the EGR blank/cleaning the intercooler, should I attempt to take off the intake manifold and give it a good clean while I'm doing everything else? I'm not super mechanically minded but I can fumble my way through most jobs, am I going to cook something trying to do this? I was thinking of using a few cans of liqui moli intake cleaner but I've read its better for upkeep of a fairly clean manifold, not for cleaning a clogged one.

Cheers,

Jay

 

[Old.Tony]

Removing the intake manifold will require a new gasket, but is a reasonably straight-forward task. It would be possible to use a vacuum tool and clean most of the muck from the intake manifold through the EGR valve, but most of us (myself included) don't have that sort of vacuum equipment handy.

If I was to try it with mine, I'd remove the EGR valve, and using a reasonable amount of duct tape, I'd fit a piece of clear flexible tube to the nozzle of my wet & dry vacuum cleaner and go for it.

 

[mrmeme1212]

Yeah okay I'll give that a crack. Might do that in conjunction with a few cans of the cleaner.

 

[Phunk]

Hey brains trust. I've been having this problem for a few weeks, I've seen similar threads on here and have tried all the fixes to no avail. On cold start my 07 D40 struggles to start sometimes, it idles rough, and sometimes stalls (rarely). When taking off it has severe power loss at ~1500 rpm and 2000rpm but drives fine above that. It's almost stalled when hitting ~1500 rpm, the revs and power just drop suddenly. Once warm it drives like a dream. I've replaced the SCV and BCV, replaced vacuum hoses and fuel filter, cleaned MAF and reset the ECU (which has never thrown a fault code). I don't know what else to do, any thoughts?

Don't want to be a party pooper. but isn't this a tell-tale sign of the Timing Chain on the YD25?

Car only runs when on throttle, but ECU will stall the engine out when it sees the timing off?

 

[mrmeme1212]

Don't want to be a party pooper. but isn't this a tell-tale sign of the Timing Chain on the YD25?

Car only runs when on throttle, but ECU will stall the engine out when it sees the timing off?

Wouldn't it throw a code for something that big? And wouldn't it have the flat spot all the time? I really hope it's not the timing chain I can't afford something like that

 

[Phunk]

Wouldn't it throw a code for something that big? And wouldn't it have the flat spot all the time? I really hope it's not the timing chain I can't afford something like that

This is from YD25.com.au

"The computer in D40 vehicles with VIN MNT is programmed to check the correlation between the camshaft and the crankshaft and shuts the engine down within 5 seconds of cold start-up when the fuel pump drive timing chain is worn however if the engine is hot (over 65 degrees C) then it will idle and not shut down. To confirm that fuel pump timing chain wear is the problem, ensure the engine temp is below 65 deg, disconnect the camshaft sensor plug located on the cylinder head, left hand side rear, and restart the engine. If the engine does not shut down after 5 seconds then the fuel pump drive timing chain needs replacing.

In all other models VINs VSK MNT JN1, if the engine only runs for a short time at idle or if it only runs when the revs are kept over 1500 rpm then this is an indicator of serious wear to fuel pump drive timing chain, camshaft timing chain and guides. As there is no computer shut down in these models, the engine will run until the fuel pump drive timing chain breaks.

In any model, if the engine has a timing chain rattle on start up and the noise goes away just after the oil light goes out or if there is no noise when cold but the chain rattles when hot then this is an indicator of failure of the top tensioner. These symptoms can occur at relatively low km. A failing top tensioner is a serious fault and needs immediate attention. Our timing chain replacement kit includes genuine tensioners with a special part that improves their reliability.

The signal pattern of the crank and cam angle pick-ups can be checked with scoping equipment. New chains will show overlapping cam and crank signals. Worn chains will show time delay on the cam signal. The MN D40 shuts down when a delay of 18 degrees is detected. Use this method with caution as it will not identify if there is just one worn link."

Just some food for thought, I'm dreading this as well as mine has 250 on the clock and lifespan is 300k.

I usually research the hell out of my cars before purchasing, no idea how I missed this one.

Hopefully yours is just a vacuum leak or something dodgy like a PCV.

 

[mrmeme1212]

This is from YD25.com.au

"The computer in D40 vehicles with VIN MNT is programmed to check the correlation between the camshaft and the crankshaft and shuts the engine down within 5 seconds of cold start-up when the fuel pump drive timing chain is worn however if the engine is hot (over 65 degrees C) then it will idle and not shut down. To confirm that fuel pump timing chain wear is the problem, ensure the engine temp is below 65 deg, disconnect the camshaft sensor plug located on the cylinder head, left hand side rear, and restart the engine. If the engine does not shut down after 5 seconds then the fuel pump drive timing chain needs replacing.

In all other models VINs VSK MNT JN1, if the engine only runs for a short time at idle or if it only runs when the revs are kept over 1500 rpm then this is an indicator of serious wear to fuel pump drive timing chain, camshaft timing chain and guides. As there is no computer shut down in these models, the engine will run until the fuel pump drive timing chain breaks.

In any model, if the engine has a timing chain rattle on start up and the noise goes away just after the oil light goes out or if there is no noise when cold but the chain rattles when hot then this is an indicator of failure of the top tensioner. These symptoms can occur at relatively low km. A failing top tensioner is a serious fault and needs immediate attention. Our timing chain replacement kit includes genuine tensioners with a special part that improves their reliability.

The signal pattern of the crank and cam angle pick-ups can be checked with scoping equipment. New chains will show overlapping cam and crank signals. Worn chains will show time delay on the cam signal. The MN D40 shuts down when a delay of 18 degrees is detected. Use this method with caution as it will not identify if there is just one worn link."

Just some food for thought, I'm dreading this as well as mine has 250 on the clock and lifespan is 300k.

I usually research the hell out of my cars before purchasing, no idea how I missed this one.

Hopefully yours is just a vacuum leak or something dodgy like a PCV.

Since I replaced the SCV it hasn't stalled on me, and it will idle well below 1500 it's just a little rough sometimes so hopefully I've dodged a bullet there, I've got about 210K on the clock and I know the previous owner maintained the car well so fingers crossed.

 

[Old.Tony]

Since I replaced the SCV it hasn't stalled on me, and it will idle well below 1500 it's just a little rough sometimes so hopefully I've dodged a bullet there, I've got about 210K on the clock and I know the previous owner maintained the car well so fingers crossed.

It's not only maintenance, it's how the vehicle is driven and the quality of the components. I can't speak for the latter, but I had to have the head in my car replaced about 4,000km ago (we've hardly driven the car since) and the mechanic who did the job thought I'd had the timing chains done within the last 50,000km.

That was at 361,000km and I informed him that he was the first person to actually see the timing chains since the car had been assembled.

If you use a good oil and get it changed regularly, the camshaft chain tensioners (which appear to be the root cause of the failures) won't gum up and won't start sticking allowing the chain to prematurely fail.

 

[mrmeme1212]

It's not only maintenance, it's how the vehicle is driven and the quality of the components. I can't speak for the latter, but I had to have the head in my car replaced about 4,000km ago (we've hardly driven the car since) and the mechanic who did the job thought I'd had the timing chains done within the last 50,000km.

That was at 361,000km and I informed him that he was the first person to actually see the timing chains since the car had been assembled.

If you use a good oil and get it changed regularly, the camshaft chain tensioners (which appear to be the root cause of the failures) won't gum up and won't start sticking allowing the chain to prematurely fail.

I've been paranoid since this morning looking for videos with timing chain noises, mine doesn't seem to be making any noises but I'd be lying if I said I had an ear for these things. All I can hear is diesel rattle. What do you guys think?

 

[Old.Tony]

It sounds ok from the video (that I can tell). Mine sounds the same, and I know my chain's in great nick.

The trick will be putting a mechanic's stethoscope on the timing chain cover and listening to that. You should be able to hear the chain sliding over the tensioner, but not hear it slapping the tensioner. If it's worn, you might also hear it engaging the sprockets (stretched chain).

The best method is visual inspection, and it's sad that Nissan didn't include an inspection port in the timing chain cover.

 

[mrmeme1212]

Forgot to update this thread, turns out the O-ring for the water sensor on the fuel filter was split, draining the fuel out overnight and drying by morning. I still think the SCV was dodgy, because changing it improved all the other symptoms, but the O-ring was definitely causing the rough idle methinks.

 

[Rabbie Tewe]

I had the same issue with my Navara d40 and I changed the SCV and was back to normal.