Engine power loss and cutting out under load

[Colhoneyus]

I’ve a 2004 Nissan Navara d22 with DI zd30 engine, that I’ve been having quite some dramas with. Just replaced the turbo, air filter box and egr blanked recently as it was operating as if the turbo had failed. Functioned fine (still no turbo power) for about a month now it’s lost power (flat spot initially from idle to full revs) and seems to electrically shut down under load? - no power in first when driving then starts to take off in second, then shuts down? We’ve run various diagnostics that have only displayed throttle pedal fault.
New neutral position switch just fitted but not performing as suggested on this forum. Any suggestions would be truly appreciated as there’s quite a few people here in town scratching their heads

 

[Horatius]

Wouldn't the accelerator position switch be likely if that was the fault showing? How/why did you rule that out?

Normally they would just go and you would have no accelerator, but they don't have to do this. From memory they are a 5.2k-0-5.2k ohm variable resistor so there's the possibility of all sorts of weird symptoms. In the manual somewhere it explains how to test them.

 

[Colhoneyus]

Cheers Horatius, we had .48v at idle and 4.8v at full throttle which we thought was acceptable . Also have tried three different diagnostic tools and cannot connect. I will take it off and check it properly though

 

[Horatius]

That sounds about right, but the areas between idle and full throttle could be intermittent? Afaik (though not sure) they would be a wire wound type, so if the contact isn't good at various stages the resistance and hence voltage could be all over the place. Unfortunately digital meters aren't great for checking this due to sampling rate and so on, it's much easier to watch a needle slowly increase with the old analogue type (might be showing my age there lol). A long shot perhaps but worth checking thoroughly, do you know anyone or have any mates with a nav? Would be easy just to swap it to see if problem persists.

ps. There is a method to check the fault codes using the mil light, if you have a look you'll find it here somewhere.

 

[Horatius]

Something else to look for that could account for the "no turbo power" problem you mentioned initially, is the boost pressure sensor. If they go or the hose is cracked or leaking, the turbo won't reach very high boost, nor will it won't throw any fault codes. They can be really gutless, like driving without a turbo. Usually only noticeable in the higher gears though, so if your's is lacking power from 1st is probably something else. Worth keeping in mind though.

 

[jack.ocholoose]

Something else to look for that could account for the "no turbo power" problem you mentioned initially, is the boost pressure sensor. If they go or the hose is cracked or leaking, the turbo won't reach very high boost, nor will it won't throw any fault codes. They can be really gutless, like driving without a turbo. Usually only noticeable in the higher gears though, so if your's is lacking power from 1st is probably something else. Worth keeping in mind though.

I just replaced my turbo ,bit of a mission and a lot of cussing and swearing don't forget to clean and pain exhaust manifold and turbo with heat proof paint.