Another loss of power thread

[Tms40]

Ok first noticed this after pulling up at a set of lights. Been driving for around 150k with no noticeable problem. As I went to take it it sounded like the snorkel was making a real sucking of air sound as I went up through the revs and gears. Sounded like the snorkel but driving it hard to pin point, just as likely to be from under the car or engine bay. Once at a cruising speed it seemed to disappear. If I knocked it into neutral and revved it no “sucking” sound, just under load but cruise control 110km and no problem and no noise. But acceleration up a hill or overtake and it’s back. Climbing the Cardwell Range it usually accelerates up in 6th gear easily but not so today. Was flat out getting over 110. The car is blowing no smoke. Any ideas?

 

[ericcs]

maybe your boost control solenoid, or the vac lines from the bcs that go over the top of the engine. common d40 issue.

 

[Old.Tony]

Entirely possible it's your BCS/vac lines, you need to monitor boost pressures to be sure.


Did you look at the grille covering the intake of the snorkel? One guy that rolled in to Kloster Nissan didn't and if he had checked, he'd have seen his grille was missing. It was found, later, down the snorkel tube along with the owl that dislodged it. You might check yours!


Also have a look at your air filter and make sure it's not really dirty.


When you are NOT in drive and the vehicle is not moving, the ECU is smart enough to know not to punch the boost or overfuel the engine. Revving these cars at idle isn't going to reveal a lot.


If there's no smoke at all, you'd have to think it wasn't air, but control - although fuel input is dictated partly by the input from the MAFS (which measures intake airflow and temp, and if airflow is blocked...).


I think it would be worth checking the cheap stuff first. Pull the air filter out, check the air chamber for excessive dirt which may indicate a need to further disassemble the air filter box and inspect/clean the baffling.


Because of the turbocharger, suction is going to be generated by the turbo but the sound will come from somewhere a little higher up.


Perhaps you could also check that your PCV hose is still in good condition, this hose goes from the top of the engine at the rear across to the air intake just in front of the turbo.

 

[Czechmate]

Boost control vac lines are a big culprit for random power issues

I discovered mine had turned to cracked dusty pieces of junk
Also the boost sensor plastic had become brittle and a spigot had snapped off inside the old rubber tubing
The vehicle had only done 90,000 ks

I replaced the vac lines with silicone ones from autobarn, and also replaced the boost control sensor that the lines are plugged into

The new boost sensor had a new part number, the guys at Bridgewater nissan in sa told me the sensor had been upgraded for that model (07 STX d40)
According to the torque OBD app i now get around 2 psi more boost

 

[Tms40]

This is a 2014 D40. All the hoses appeared to be in good condition. Mechanics located an issue with the intercooler hose. Failed clip that holds the hose to the intercooler pipe.