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Discussion Starter #1
this might just be the effect of going from owning a zippy little car, to a zd30 patrol, but i feel like i have no guts up hill. i regularly have to drop to 3rd gear to get up highway hills, not even overly steep. doing 100km/h on the highway in 5th gear, i have to drop to 4th the second theres any incline, and often down to 3rd. i have a boost gauge, and have noticed that as soon as the car reaches a hill, the boost drops off. so i drop a gear to keep boost up and EGT down, and if i didnt drop a gear, then i wouldnt get to the top. i have replaced the maf, cleaned and flushed the intercooler, checked the actuator works properly, i cant think why i would have no power. is this just standard patrol behaiviour? i can understand needing 3rd gear for towing up a hill, but for daily driving without towing, it seems like i should have more power. any help would be greatly appreciated
 

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GUII ZD30DI Wgn
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Something going on if boost is dropping when the vehicle sees a hill, what boost control do you have, what model DI is it? what max boost are you seeing on your gauge? what boost cruising at 100k on flat? What EGT's are you experiencing? Have you read the NADS section in the DI archives? are all your vacuum hoses in perfect condition? as much info as you can to help us help you.

From a zippy little car to a std ZD30 is like chalk and cheese! Been there done that and have dozens of T shirts to prove it ;).
 

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NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
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Geeyoutoo is right. Most probably your turbo does not work at all.
check the rod below the actuator.
Motor off, the rod should be down at its maximum.
Motor on, idle, it should be all up. If it does not move up, you have no turbo, and no power.
Most probably a problem with old vacuum hoses. Buy 3m of 3mm vacuum hose (I like the blue colored ones) and replace them all. cheap.
 

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Discussion Starter #4
The car is a 2001 ST zd30ddti.
The actuator rod works perfectly. I've only recently bought the car, so unfortunately haven't got EGT gauge, dawes/needle, or EGR block, the ecu still has full boost control. I have a boost gauge though.
At 100km, cruising I get a steady 10-15psi boost, but if I floor it the boost drops off to below 5psi, and not only can I see it on the gauge, but I can hear the engine get significantly louder as the boost goes. As for max boost. Generally it seems to be limited at around 18psi, however I have seen it hit 20 very occasionally.

I will buy the vaccum hose today and get that done, is that likely to be the cause. The actuator rod moves as intended
 

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GUII ZD30DI Wgn
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The vacuum pump on a ZD30 will pull between 28" to 30"Hg on average, Mine has always been on the low end at around 28"Hg, the ECU then decides what percentage of vacuum will be distributed by the Vacuum Solenoid (which is mounted under the side of the airbox) according to feedback it gets from many sensors, the normal distribution starts at around 55% and reduces as you accelerate to make the VNT arm 'dance' to the tune of the ECU. So you see there could be a few issues here, it is a matter of a process of elimination. Cruising boost is good and ECU control will see dips and spikes as you drive normally. Do you have cruise control, and if so does this dramatic drop occur then?

over 90% of issues in this vein we hear of are caused by damaged vacuum and boost hoses. Start with a full check of all hoses and eliminate them.
 

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Discussion Starter #6
The vacuum pump on a ZD30 will pull between 28" to 30"Hg on average, Mine has always been on the low end at around 28"Hg, the ECU then decides what percentage of vacuum will be distributed by the Vacuum Solenoid (which is mounted under the side of the airbox) according to feedback it gets from many sensors, the normal distribution starts at around 55% and reduces as you accelerate to make the VNT arm 'dance' to the tune of the ECU. So you see there could be a few issues here, it is a matter of a process of elimination. Cruising boost is good and ECU control will see dips and spikes as you drive normally. Do you have cruise control, and if so does this dramatic drop occur then?

over 90% of issues in this vein we hear of are caused by damaged vacuum and boost hoses. Start with a full check of all hoses and eliminate them.
I don't have cruise control. Layer this arvo I'll be replacing all my vacuum hoses, I'll let you know how that goes
 

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Discussion Starter #7
Geeyoutoo, how many hoses are there to replace in total. I've replaced 3 so far, a tiny one that goes from one part of the solenoid to another, 1 that goes from the solenoid to under the intercooler, and one that goes from the solenoid to the actuator. Are there any more or is that all of them??
 

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From vac pump to under IC. But check IC hoses as well for evidenc of splits etc.
 

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Discussion Starter #12
Never mind, I found it, and replace the 2 short hoses there, however it seems to have made no power difference. Any other hoses??
 

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As said earlier check IC hoses for splits/damage. Especially the hoses from turbo to IC, you said earlier you could hear a change in engine noise when you accelerated and boost dropped off.
 

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NISSAN PATROL Y61 3.0 Di (ZD30) 09/2000
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if you go to the archive, you have all technical manuals., thanks to GeeYouToo and his mates. Check section 'EC'.
Here is an extract with all vacuum hoses. Vaccuum pump on the left end.
Pump is below you car, front left, visible from underneath.
There are many tiny sections of vacuum hoses.

516203


If the pressure drops suddenly, it is due to vanes being at that moment too opened. Lack of vacuum gives that effect.
 

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Discussion Starter #15
As said earlier check IC hoses for splits/damage. Especially the hoses from turbo to IC, you said earlier you could hear a change in engine noise when you accelerated and boost dropped off.
Okay, so I pulled apart my intercooler piping today, thoroughly inspected it and found not splits or leaks. I have also now replaced all vacuum hoses, as per that diagram, including the tiny ones. So far, nothing has made a difference.

if you go to the archive, you have all technical manuals., thanks to GeeYouToo and his mates. Check section 'EC'.
Here is an extract with all vacuum hoses. Vaccuum pump on the left end.
Pump is below you car, front left, visible from underneath.
There are many tiny sections of vacuum hoses.

View attachment 516203

If the pressure drops suddenly, it is due to vanes being at that moment too opened. Lack of vacuum gives that effect.
What could be causing this lack of vacuum. If all my hoses are replaced, and my IC piping is fine, where else could the leak be??
 

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Is it possible to mount a vid cam under the bonnet pointed at the turbo to monitor the VNT arm while driving, as said earlier the VacSol controls the amount of vacuum the VNT gets.

Before doing that, without any measuring devices you can fit a bit of tube onto the VNT diaphragm and suck like crazy, this will make the arm go to the top of the stroke with minimal effort, you can pull 18-20"Hg by mouth and that is more than enough, you can then quickly put your tongue over the end of the tube to hold vacuum and see whether the diaphragm is leaking. If your boost gauge is dropping to 5psi and under while driving and the issue is vacuum/ECU/VacSol related it will show in the vid. Not easy but I have done this many times over the years while researching different aspects and it will answer a few questions.

We just need all the clues you can muster, under normal conditions that boost drop off shouldn't happen like that. A quick question seeing as yours is a manual does this boost drop off occur above a certain speed and in a particular gear? ie does it happen in 4th at say 80k? I won't put words in your mouth so I won't go to deep on that one for the moment, just get back to us on that.
 

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Discussion Starter #17 (Edited)
Is it possible to mount a vid cam under the bonnet pointed at the turbo to monitor the VNT arm while driving, as said earlier the VacSol controls the amount of vacuum the VNT gets.

Before doing that, without any measuring devices you can fit a bit of tube onto the VNT diaphragm and suck like crazy, this will make the arm go to the top of the stroke with minimal effort, you can pull 18-20"Hg by mouth and that is more than enough, you can then quickly put your tongue over the end of the tube to hold vacuum and see whether the diaphragm is leaking. If your boost gauge is dropping to 5psi and under while driving and the issue is vacuum/ECU/VacSol related it will show in the vid. Not easy but I have done this many times over the years while researching different aspects and it will answer a few questions.

We just need all the clues you can muster, under normal conditions that boost drop off shouldn't happen like that. A quick question seeing as yours is a manual does this boost drop off occur above a certain speed and in a particular gear? ie does it happen in 4th at say 80k? I won't put words in your mouth so I won't go to deep on that one for the moment, just get back to us on that.
I'll get that vid done at some point. As for the gearing, it's more like the engine just can't boost under load. In 4th gear at 80km, I'll have about 3psi. The once I get to about 95 in 4th gear, it shoots up really quickly to about 15, more if I'm flooring it. But as soon as it sees a hill, back down to under 5. I'll try and get a video of this if it helps. I can replicate what happens at Hills, simply by cruising in 5th gear at 100km, then flooring it. But the general gist is that, It doesn't boost until High rpm, or when the engine isn't working hard. It's as if it won't boost until the engine doesn't need boost to keep going, as soon as the engine needs to boost to keep the rpm up, the boost drops off. So as you can see in the vid, at 100km, just feathering the throttle enough to maintain my speed, the boost is fine. But when I floor it, simulating the excess load on a hill, the boost goes way down, and the car hardly accelerates.

I'll also say I did the suck test you mentioned, sucking as hard as I can, I could only just get the rod to move about half a cm up. Buy pinching the line, and then sucking again, and repeating a few more times I was able to raise the rod to the top. When the line was pinched it was holding the vacuum. Is the rod meant to be that hard to move? It lifts when I start the car up but I had to nearly blackout to get it to the top by sucking, and I'm not a smoker/unfit.


edit - added the video I just took of the boost gauge on a hill

Boost dropoff vacuum problem
 

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I woudn't swear on it, but from the top of my head, isn't that behaviour one of the issues we all had on our manual ?

IF RPM still goes up on when you floor it, but boost suddenly drops off, I am afraid it may be linked to the (bad / wrong) way the ECU is managing the vanes.

What you can do to confirm, is to get a boost gauge which goes to negative values ( mine goes from -1000mbar to +2000 mbar), and connect it to the actuator hose.

At idle, it should show around -500mbar ( or the equivalent in Psi ), and going up with Revs to -200mbar when you drive. Most of the time, it should be in between (vanes of the turbo half open).

The sudden drop in boost will be seen as a sudden raise from where the gauge was to -200mbar.
 

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I woudn't swear on it, but from the top of my head, isn't that behaviour one of the issues we all had on our manual ?
Not to that extent.

@Vamphersi I can raise it easy so not sure what is going on there, what is happening in that vid is not normal. Maybe go to supercheap and pick up a cheap vacuum brake bleeder, I use the vac pump in that to measure vacuum at the VNT when I set it up.
 

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Discussion Starter #20
I can raise it easy so not sure what is going on there, what is happening in that vid is not normal. Maybe go to supercheap and pick up a cheap vacuum brake bleeder, I use the vac pump in that to measure vacuum at the VNT when I set it up.
Is there any way to change how easy/hard it is to raise that rod? Because for me its super stuff, takes me a few sucks to get it to the top, pinching the line in between
 
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