GU patrol replaced MAF sensor, now have power loss

Submitted: Tuesday, Mar 06, 2007 at 10:53
ThreadID: 42960 Views:14690 Replies:5 FollowUps:19
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Hi all,

I own a Dec 2000 3ltr patrol (125K Klms), it's my first time on the forum but I've read up on most of the GU forums and have been both shocked and informed.
I'm stuck with it now so I have to make the most of it.

Anyway, I cant find anything about my specific problem.

I originally had a blown I/cooler and had one of the guys at my local dealer run a diagnosis check on it.

The only error was the turbo pressure.
He suggested to replace the MAF, so I did and now am experiencing a loss of power that occurs occasionally when cruising on highway (at about 3000 rpm).

The problem goes away when I quickly remove the acc pedal and then depress it.
Its only happened since the new MAF, everything else seems ok.

I've gone back to them suggesting that its a part fault but have to wait as they are trying to get info from Nissan Aust.

I'm a little doubtful that its a faulty MAF as I've also heard of 2 other exact cases, (series II spec) apparently the MAF has been superseded and if so, am a little worried that its configured to later model specs.

Can anyone enlighten me?

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Reply By: goingplatinumcomau - Tuesday, Mar 06, 2007 at 10:58

Tuesday, Mar 06, 2007 at 10:58
Hi Ta

Who is your local Nissan Dealer as some are worse than other's.

AnswerID: 225586

Follow Up By: Dingo77 - Tuesday, Mar 06, 2007 at 12:29

Tuesday, Mar 06, 2007 at 12:29
Hi Jon,

It's a mob over at Essendon.

By the way, my names not Ta :)
FollowupID: 486522

Reply By: Batman69 - Tuesday, Mar 06, 2007 at 11:19

Tuesday, Mar 06, 2007 at 11:19

I had a 3lt GU with the same problem, loss of power then remove foot off pedal and then when back on all OK. Happened quite frequently and was quite annoying.

The issue with mine was related to the injector pump. The MAF sensor replacement may be coincidental, therefore it's the injector pump or in your case the MAF sensor may have caused the issue.

My uncle had the same problem with his GU, they replaced the injector pump at 46k (under warranty) and fixed the problem.

Unfortunately my GU was out of warranty so I didn't want to pay enormous amounts to have the injector pump replaced also had a very noisy gearbox as well so I flogged it off.

All the best finding out whats wrong.

AnswerID: 225590

Follow Up By: Dingo77 - Tuesday, Mar 06, 2007 at 12:35

Tuesday, Mar 06, 2007 at 12:35
Thanks Steve,

You're probably on the money, the pump is just about the only thing I haven't replaced so far....not having much luck with this thing and I cant even sell it right now.

Do you have any info about the pump fault? What I mean is, does it need a reco or can a specific component be replaced?

I'll wait and see what the Dealer tells me as well.


FollowupID: 486523

Follow Up By: Member - John (Vic) - Tuesday, Mar 06, 2007 at 12:48

Tuesday, Mar 06, 2007 at 12:48
Sorry to say going on past posts over this subject I reckon the dealer will tell you its about $5,000 for a new pump.
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FollowupID: 486525

Follow Up By: nowimnumberone - Tuesday, Mar 06, 2007 at 20:19

Tuesday, Mar 06, 2007 at 20:19
we just did a change over pump on a 3ltr
total cost fitted ect was around $3500
FollowupID: 486569

Reply By: On Patrol (Aust.) - Tuesday, Mar 06, 2007 at 17:02

Tuesday, Mar 06, 2007 at 17:02
I had exactly the same problem with mine last year after a snorkel was fitted.

I was told it was the MAF sensor. Bulldust.

It turned out that when the fool that took it off put it back he did so with the vacume hoses reversed. So swap the hoses going onto the air cleaner and hey presto no problem. the two concerned are the two nearest to the rear of the car, reverse them and I am sure you will have no more problem.

What is happening now is Over Boost causing the car to suddenly lose power and when you back off and re apply pedal pressure it resets the boost and as you accelerate at around 3000 rpm it comes back.

It sounds too simple to be true but i can assure you thats the problem.

It took me a full 2 weeks to find out myself.
On Patrol
AnswerID: 225643

Follow Up By: On Patrol (Aust.) - Tuesday, Mar 06, 2007 at 17:09

Tuesday, Mar 06, 2007 at 17:09
If you want to speak to me, e-mail me on, and i will send you my number.

I am 99% sure you have the same problem.
FollowupID: 486546

Follow Up By: GQ_TUFF - Tuesday, Mar 06, 2007 at 17:17

Tuesday, Mar 06, 2007 at 17:17
I can only agree, as I watched "on patrol" go greyer and balder as this problem was sending him crazy.....well crazier than normal. And it really was as simple as the hoses being on the wrong way too bloody simple sometimes!!!

If you haven't already I suggest you do e-mail him and have a chat

Cheers Stefan
FollowupID: 486548

Follow Up By: David from David and Justine Olsen's 4WD Tag-Along - Tuesday, Mar 06, 2007 at 17:26

Tuesday, Mar 06, 2007 at 17:26
It does sound like a typical overboost situation. Would be worth checking the hoses aren't mixed up.
FollowupID: 486549

Follow Up By: On Patrol (Aust.) - Tuesday, Mar 06, 2007 at 17:56

Tuesday, Mar 06, 2007 at 17:56
These are the hoses I refer to.

go back to the turbo control and a third goes back into MAF area.(dont touch the third one) sawp the other two IF the rear one has no valve body on it, the valve should be on the middle one as shown in picture.
FollowupID: 486552

Follow Up By: Im.away - Tuesday, Mar 06, 2007 at 18:54

Tuesday, Mar 06, 2007 at 18:54
Crikey!! I don't own a Nissan, But I do have an NP Pajero that is doing exactly the same thing. The dealer has no idea what it is and I'm starting to lose it! After reading this I dashed out to the carport and had a look. While the components don't look exactly the same, the same principle is clearly on show!

I've rung the dealer and booked mine in for tomorrow. It's still under warranty so they can deal with it. Thankyou, thankyou, thankyou!
FollowupID: 486560

Follow Up By: On Patrol (Aust.) - Tuesday, Mar 06, 2007 at 19:09

Tuesday, Mar 06, 2007 at 19:09
Good on Ya Im.Away

If i knew I was helping an Itsibitsi owner i would never have posted that reply. LOL.
Good luck tomorrow mate. Hope it works for you.
FollowupID: 486562

Follow Up By: Dingo77 - Wednesday, Mar 07, 2007 at 08:41

Wednesday, Mar 07, 2007 at 08:41
Wow! this input is really appreciated, thanks to everyone.

This reply drags on a bit so a warning to you all.

Before I read the latest responses (last night) I had the urge to test the original MAF (as I knew it wasn't happening with this one), well I was right, no power loss.
This other MAF however caused the truck to drive like a slug (as it used to) with little or no boost. I might be completely wrong on this but I can only assume that the problem wasn't obvious back then due to the overall poor engine output and now with the new sensor installed its raised the boost levels enough for it to cause an issue.

In reference to 'OnPatrol's' suggestion, I wish it was as simple as reversing the hoses, I had a look at my vacuum layout and found that all was ok.
I too had a snorkel fitted some time ago and have seen some shocking work done by 'so called mechanics /fitters'.

I've also checked the factory manual and confirmed that these hoses were ok, I'll check the whole vacuum system soon.

Another stab in the dark is that with the old MAF, the fuel pump didn't need to deliver high amounts of fuel so it didn't 'struggle' to keep up with load. Since the new MAF it may have caused an increase in flow rate causing it to fail. This theory isn't very strong as one would think that this would also occur during hard acceleration and not during cruising, also when throttle is backed off and re-applied the pump has no issue with supplying required fuel.

I called about 10 different dealers and a few private mechanics and the best I could get was 'you'll need to bring it in and that it would be caused from:
Turbo system
Fuel pump
Accelerator potentiometer (fly by wire system).


FollowupID: 486661

Follow Up By: Batman69 - Wednesday, Mar 07, 2007 at 10:48

Wednesday, Mar 07, 2007 at 10:48

This might be worth a try.

Go to your Nissan dealer, ask them to plug in their testing equipment to the ECU and go for a drive (insist that the car is driven until the problem arises). If the issue is related to the injector pump a diagnostic fault will register. This is the only way mine could be detected as faulty. If it's not the pump then some other fault may come up on the diagnostic tool.

Good luck.

FollowupID: 486681

Follow Up By: Dingo77 - Thursday, Mar 08, 2007 at 18:21

Thursday, Mar 08, 2007 at 18:21
Yeah no worries Batman,

Good plan, I have to wait till next week to do it as their diagnostics unit is out of action.

FollowupID: 487001

Reply By: GQ_TUFF - Wednesday, Mar 07, 2007 at 17:14

Wednesday, Mar 07, 2007 at 17:14
in reference to the hoses.....for the sake of a couple of minutes of your time woundn't you just reverse them and see what happens??? if thats not it at least it is out of the topic....I know from my own experience they all start to look the same after a black spagetti every where !! LOL

Cheers Stefan
AnswerID: 225867

Reply By: Chaz - Wednesday, Mar 07, 2007 at 20:07

Wednesday, Mar 07, 2007 at 20:07
I may be way off base here, but I suspect the VNC control solenoid does “meter” vacuum to the actuator. That small green filter is there to stop impurities from entering the valve, but if the valve gets stuck (open) the same symptoms will appear. If you check your diagnostic faults and get a 0905 code, then you have an overboost situation which would account for your aftercooler problems. This won’t illuminate the “Check Engine” lamp, but will register a fault code (0905 Intake air pressure sensor) and resetting the throttle will clear it.

I would be checking the valve, by fitting a short hose to Port “A” (middle port from vacuum pump), and removing the other two hoses. Then blow down the hose and you should only get air exiting through port “C” (hose to air filter). Then energize the solenoid and blow. You should only see air from Port “B”
If you get air flow through port “B” with the solenoid de-energized, your valve is faulty.
There is some discussion about this issue HERE
AnswerID: 225908

Follow Up By: Dingo77 - Thursday, Mar 08, 2007 at 22:02

Thursday, Mar 08, 2007 at 22:02
Hi Chaz,

Not sure what you mean by 'meter' but according the the the factory manual the name of the solenoid valve is a variable nozzle turbocharger control (VNTC) solenoid valve, and the name of the actuator (mounted on the turbo) is a (VNTC) control actuator. I assume this refers to the turbo having the variable part to it.

The test for the the actuator involves comparing vacuum/rod stroke amount.
-46.9 KPa /0.2mm, to
-9.09 KPa /5.0mm

Seeing that the stroke of the actuator is governed by pressure I can only assume that the pressure changes originate from the vacuum pump, which would be governed by engine speed, can anyone confirm this?

Also, the name given to the green 'filter' is a 'damper', I took mine off today and blew through it from both ends and in both cases air flow was present. Maybe the 'damper' controls the flow rate so as not to cause sudden changes to the actuator....not sure.

I did check the solenoid ports (as you suggested) and everything checks out ok. I'll look into this area further though, that link you sent was pretty full-on.

Off the topic for a minute -can anyone tell me where their temp gauge sits? mine had stayed just below 1/2 since I've owned it -even after changing the thermostat, replacing coolant and disabling the EGR (before the valve). The engine doesn't seem hot.

I'll keep at it (and even flip vacuum hoses around) and post something if I have any success.

FollowupID: 487056

Follow Up By: Chaz - Thursday, Mar 08, 2007 at 23:08

Thursday, Mar 08, 2007 at 23:08
Hi, Dingo77,
Sorry I didn’t explain myself well. By “Meter”, I meant that the valve controls vacuum flow. Some people say it’s on or off, by testing it with a meter or test lamp, but some say it’s controlled by “Pulse Width Modulation”, which would be from the ECU. I wonder if the voltage could be controlled by the ECU and the valve is in fact a needle valve that increases vacuum as the voltage increases. You may be correct by saying that the pump increases vacuum with engine rpm, but boost increases and decreases regardless of rpm.
You are correct, that little green thing is called a damper. My mistake, but I think it does more filtering than dampening.
If you swap the A & B port hoses around, you may find the VNC actuator won’t bleed down when the ECU want’s to decrease boost. Also if you have blocked the EGR, you need to lower your boost to compensate. Blocking the EGR will increase boost levels at times because there will be no boost lost through the EGR system. This is why they run such high boost levels (to overcome EGR) and why boost suddenly drops off (to allow for EGR).
My ZD30, like yours has always ran just under half way on the temp gauge.
Good luck with this and I hope you find the cause of the problem.
FollowupID: 487088

Follow Up By: Dingo77 - Friday, Mar 09, 2007 at 08:37

Friday, Mar 09, 2007 at 08:37
Hi Chaz,

I dont want to start the EGR saga again but I read up on this topic (post# 36378) some time ago and from this (and due to finding a bucket of soot in my manifold) I decided to block mine off. The results were fantastic, no smoke and no flat spots, it was like driving a new car.
The forum didn't mention anything about increasing boost levels however (or compensating for it), but what you say does make sense.

From the post I know that you've blocked yours off, what have you done to compensate? from what I've been told, you cannot adjust boost on the turbo.

The last thing I want in my ZD30 is extra boost! I might remove the EGR plugs and see what happens.

By the way, I had a look at the turbo vacuum setup in a friends Series III and it is exactly the same as mine.

Cheers, Enz
FollowupID: 487123

Follow Up By: Chaz - Friday, Mar 09, 2007 at 11:31

Friday, Mar 09, 2007 at 11:31
Hi Enz,
Blocking the EGR system is probably the best thing you can do for your motor, but peak boost needs to be limited. There is a small grub screw just behind the VNC actuator rod on the turbo. Don’t adjust the length of the rod because that will change when you get boost, but by winding the grub screw down about half a turn you will limit how far the VNC lever comes up and opens the vanes. This LINK shows how, although it’s a bit hard to follow (it needs to be translated from French).
Making this adjustment should limit your maximum boost provided your exhaust is standard.
I spent a considerable amount of time tuning on a dyno and found that my Patrol didn’t make any more power over 16psi, so I limited mine to 18psi. It was going over 25.
I have since gone away from this method, because after other mods, my boost was too high again, so I now use a manual controller that allows me to adjust boost while driving.
This LINK shows the VTNC in operation.
FollowupID: 487149

Follow Up By: Dingo77 - Friday, Mar 09, 2007 at 12:18

Friday, Mar 09, 2007 at 12:18

I'll give it a go on the weekend...cheers.
FollowupID: 487157

Follow Up By: Dingo77 - Monday, Mar 12, 2007 at 21:33

Monday, Mar 12, 2007 at 21:33
Problem solved!

Chaz was on the money with the peak boost (see above), thanks heaps!

The ECU would go into 'safety-mode' when boost levels got too high (all this with no engine warning lamp illuminated).
I made the adjustment to the actuator and have tested it thoroughly over the last three days and it runs like a dream....finally.

I missed the part about making adjustments to peak boost when I originally read the posts on EGR's. If you do decide to block your EGR's I strongly suggest make the changes to the turbo, it's too easy.
(by the way, I cant believe how clean my engine oil is since blocking the EGR)

Regarding the fuel pump, from what my dealer told me its water that kills them, he suggested to drain the water on a weekly basis (probably a bit of overkill but it would depend on where you buy your diesel from). I try to stick to busy truck stops, a bit hard when your in the middle of nowhere, I know.
Don't wait for the dash warning lamp to light up.

Thanks to all for the great help and good luck with those ZD30's.
FollowupID: 487846

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