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Discussion Starter · #1 · (Edited)
I have a 2002 GU lll 3.0 diesel patrol wagon
Towing my van today i had trouble getting power
When i put my foot down it feels like there is a block of wood under the throttle preventing me from getting more revs
Any clues?

Allan
 

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Y2KGUII ZD Wgn
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Welcome to the forum.

Does it get better when you lift your foot and then re accelerate? if so it could just be good old limp mode, cleaning the MAF is a good place to start first. If you go into the ZD30DI section and look in the archives you will find info. I'll move your post into the DI section.

There are several things it could be but limp is one of the most common.
 

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Discussion Starter · #3 ·
Yes it can get better
One minute you have the block of wood there and next minute it is ok

Allan
 

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Y2KGUII ZD Wgn
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When it does this it usually limits the boost to 10psi and will not allow a speed higher than 100k and they act like a slug, but take your foot off the accelerator and it will recover until it happens again under load.

So, start of with what was suggested, get a can of CRC CO Contact Cleaner, remove the MAF (you will need a T-20H security screw bit to remove the screws) and spray the MAF concentrating on the metal tab inside, shake and spray several times, do not physically touch the tab with anything other than the spray, replace it and drive it again, if this doesn't work we need to go deeper later.

Have you done anything to the vehicle lately, like block the EGR or fit a bigger exhaust etc? Any info like this can help us to help you.
 

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Discussion Starter · #5 ·
No i have not done anything to the vehicle
I will clean the air mass sensor and let you know how i go

Allan
 

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Discussion Starter · #6 ·
Well i cleaned the sensor today
Checked the voltages and these were ok
Also cleaned the two screens on the filter and these were a bit grubby
Took it for a run and all is working well ATM but only time will tell i dare say
Thanks for your help in this matter

Allan
 

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I have the exact same problem. If im cruising say at 80 in 5th then accelarate harder, the boost drops down to practically 0 then slowly goes up to 10... maybe I'll go to nissan n buy a new maf as mine was cleaned few weeks ago by mechanic. ....
 

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Y2KGUII ZD Wgn
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I have the exact same problem. If im cruising say at 80 in 5th then accelarate harder, the boost drops down to practically 0 then slowly goes up to 10... maybe I'll go to nissan n buy a new maf as mine was cleaned few weeks ago by mechanic. ....
Do a search on testing MAF with a multimetre, a few of us have done write ups on it some time ago, you can connect to the red wire in the MAF and earth to a good point on the engine, then start her up and take a reading, at idle with no mods you should have 1.7-1.8v (roughly) with a EGR block you should have 2.0-2.2v, you can then get someone to give it a rev and see if it rises linearly, free revving you should see around 3.5v at 3000rpm.
 

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Also get a boost and egt gauge fitted and let us know what readings you see. ;)
 

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Ok so voltages seem fine, pretty linear to rpm.. idle im sitting at 2.0v egr block. This morning on fwy at 100 was being a bit funny with boost.. sitting at around 13 then dropping off to 5 then to 0 then back to 13psi. When I accelarate it tends to drop off.. also egts sit around 300 when on 13psi then the sky rocket to about 450 500 when boost drops.... would a dawes fix this? Want to set it to 18-20 psi
 

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Needle valve and Dawes will help, you'll be able to play around with setting bit more with spool rate, limit boost to 18psi. You may still have issue but not to that extent.
 

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Start with your boost at 15psi and go from therr
 

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Ok... so dawes valve is in. I played around with it a bit but boost is still all over the place when not on full throttle. Also peak boost is never the same. Its actually doing the same thing it was before. If not worse. Im actually considering changing the turbo to a gated one.
 

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Y2KGUII ZD Wgn
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If the boost is not linear and smooth with a dawes and needle valve setup then it has been setup wrong or the turbo is cactus.
X2, to the OP, make sure you have it setup to the schematics in the DI archives, these things simply just work if they are setup correctly and you have no vacuum leaks etc, you start of at 14-15psi to make it easy on yourself in the beginning.

Go back and double check, either you have done something wrong or as DT says the turbo is shagged, but I would be expecting you to hear strange noises emanating from the turbo, and they are pretty tough so I would be leaning towards the former.

As GUEY suggests it sounds a bit like the Vac solenoid hasn't been bypassed, or you have a vacuum leak.
 

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Yes the top of the dawes is connected to the boost side and the other side tees between the vac solenoid and actuator
 

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Yes the top of the dawes is connected to the boost side and the other side tees between the vac solenoid and actuator
You don't want the solenoid anywhere in this equation, the solenoid is part of the problem not part of the solution, go back to the schematics in the NADS section and bypass it. Oh Bugga here it is.

There are several ways but this is basically what you want it to look like:

Dawes Schematic Postable.jpg

This is a bypassed Vac solenoid showing the resonator connection at the top. EDIT: Actually my Vacuum solenoid has been sitting on my workshop bench for several weeks now, I took it off as I had no where to put it when I removed the resonator, the ECU doesn't care whether it's connected or not.

2. Bypassed vac switch.jpg
 
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