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Low idle ZD30


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I bought my 2004 Y61 couple weeks ago and I noticed engine vibration and low rpm. I thought It can be fixed it easy. I cleaned MAF, and checked voltage according to instruction. Terminal one 1.65v, two 5.11v, three 3.5v and four 12.38. Any idea about terminal three voltage and where it might comes from? The idle speed is 400 rpm, cold and warmed.

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G'day mate,

 

I'm sorry but MAF sensor has no relation to engine idle speed, indeed you can disconnect and it should still idle fine. Standard idle should be at 750 RPM.

 

This looks like injection pump trouble. If you have a laptop and USB/serial interface to Consult II port you could use ECU Talk software to read ICV% (injection timing valve) of the pump. It should be 50%-70% never bellow 40%.

 

What that means that you either have air in the fuel or the IP(injection pump) fuel lifting diaphragm is broken so fuel starvation is occurring which means the pump is on the way out. 

 

Other than making sure all fuel lines, filter fittings and electrical connections and earths are secure and sound you need to read what ECU and IP controller are reporting,

 

Do a search on Bosch/Zexel VP44 injection pump issues. These pumps are lemons especially 6 cylinder versions however 4 cylinder units are also troublesome.

 

MAF pins(early 4 pins version) :

 

Pin 1 = airflow signal to ECU 1.6V-4.1V

Pin 2 = reference voltage  5 V

Pin 3 = ground

Pin 4 = vehicle voltage 12V

Edited by Rumcajs
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You can get both the software and cable/interface from ECUTalk website. www.ecutalk.com Follow the instruction on the website how to choose correct type cable interface either Consult II or fake OBD II. Or make your own once you ascertain which which type you need. Some electronic skills are required to make your own interface by getting Prolific USB to serial chip/interface and Consult or OBD plugs/terminals and data cable.


ECUTalk made cable just works and they include the software in the package. It is worth the outlay IMHO but I'm a tech so for me it is no brainer.

Regards

 

Edit: what happens when you hit the fast idle/warm up switch? Do RPMs rise or not?

Edited by Rumcajs
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Yes engine rpm goes up when heater and air con is on. I just picked up Max Ellerys workshop manual which covers all Patrol 98-09. It says there is no need to test and correct idle for ZD30 engine as it is controled by ECM.

 

The engine idle is 400 rpm and a bit of vibration in top cooler cover, is that normal or is this start of serious problem? may be there is some fault in ECM it self.

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Thanks again keeping in touch , yes, everything seems normal except low idle rpm.

 

When at idle turning heat switch on,idle goes up to 1200, when at idle, aircon switched on idle goes up to 650 rpm. But also as I mentioned in my first post, checking AMF when engine warmed up and idling,the terminal three should read 0v not 3.5v. I am wondering somewhere in engine componet sending wrong voltage to ECM to keep the idle at 400rpm.

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Thanks again keeping in touch , yes, everything seems normal except low idle rpm.

 

When at idle turning heat switch on,idle goes up to 1200, when at idle, aircon switched on idle goes up to 650 rpm. But also as I mentioned in my first post, checking AMF when engine warmed up and idling,the terminal three should read 0v not 3.5v. I am wondering somewhere in engine component sending wrong voltage to ECM to keep the idle at 400rpm.

 

I think you are reading voltage drop against the earth/ground. If you are using multimeter to measure with "Volts" function/setting in the same line (against earth/ground) than you are measuring what is called voltage drop. To me this suggests bad earth/ground connection unless you have measured against ECU earth.

 

See pic attached on explanation if you have multimeter with buzzer function you can check for continuity and also using resistance function measure actual resistance to ground. Make sure "power" is off when measuring this way. 

 

Once you have checked it check all ground connections on the engine and battery and do yourself a favor and install another earth strap between body and the chassis as well. It usually cures a lot of issues and random electrical gremlins.

 

If still not working I strongly suggest to consult/visit Bosch diesel fuel injection specialist, they can connect to the pump and check for internal codes/error which normally don't come up on your MIL (Malfunction Indicator Light). Don't waste your time going to Nissan.

 

I have seen this kinda behavior on EDC (Electronic Diesel Control) where if equipped in such way the idle speed can be adjusted by a means of cruise control switches (probably not applicable to Nissan) where default idle speed drops to 400-450 RPM during initial reset activation and than brought up to desired level and saved.

 

I really don't know how it is done on Nissan but one would think that possibly the setting got wiped/reset by some unintended action which by connecting appropriate diagnostic unit the idle speed can be reset/adjusted again.

 

This is normally the case for me when dealing with heavy vehicles diesel control.

 

Regards

post-9-0-34307200-1410340052_thumb.jpg

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I remeasured MAF third connection against engine earth in neutral position while idling, 15.2V and against battery and the body 7.4V. I also checked resistance (continuity) terminal three against engine earth, 0.4 ohm.

 

I cleaned and repaired battery area, there was lots of build up acid and damaged to paint underneath and around earth connection to the body.

 

Still there is no TDC when connecting OBD terminal one and eight, Is any benefit connecting to ECUTalk software, is it possible to make changes to ECU with this software? The J1962 cable are sold over internet with big differences in price,are all are compatible with Patrol Y61? Do you have any instruction how to make one?

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04 Patrols have what is called fake OBDII plug which is wired in Consult II protocol. So using instructions for OBDII code reading jumper is not going to work.

 

Because of this dodgy Nissan shyte the dedicated OBDII cables don't work either.

 

ECUTalk is monitoring software, it allows you to monitor/see what ECU sees, you can't make any changes to ECU with it. On ECUTalk website ==> http://www.ecutalk.com/interface.aspx the whole saga with Consult II and OBDII is explained including which wire is which,

 

OBDII.jpg

 

You can use as a guide how to wire your own interface if you are that way inclined. Get it wrong and who knows what will smoke, yet still there is a lot of mucking around to get it working e.g. correct PC drivers, OBDII hardware (plug, pins/terminals aren't that cheap) and you still need USB to Serial chip/board like one from Prolific (FTDI chip) ==>

 

http://www.obddiag.net/usb-2-serial.html

 

You could always buy cheap/cheaper Consult II interface/plug and rewire either its end or make adapter cable to go from Consult to OBDII type.

 

Note: OBDII dedicated scanners don't work with Patrols before 2007 (Common rail versions of ZD30)

 

Honestly, just pay someone else to diagnose your idle issue for you.

 

ECUTalk cabling and software is a great addition to my toolbox, indeed is for people who work on their cars themselves. If you are not one of those than pay someone else as other do.

 

Regards

 

 

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G'day mate,

 

I'm sorry but MAF sensor has no relation to engine idle speed, indeed you can disconnect and it should still idle fine. Standard idle should be at 750 RPM.

 

This looks like injection pump trouble. If you have a laptop and USB/serial interface to Consult II port you could use ECU Talk software to read ICV% (injection timing valve) of the pump. It should be 50%-70% never bellow 40%.

 

What that means that you either have air in the fuel or the IP(injection pump) fuel lifting diaphragm is broken so fuel starvation is occurring which means the pump is on the way out. 

 

Other than making sure all fuel lines, filter fittings and electrical connections and earths are secure and sound you need to read what ECU and IP controller are reporting,

 

Do a search on Bosch/Zexel VP44 injection pump issues. These pumps are lemons especially 6 cylinder versions however 4 cylinder units are also troublesome.

 

MAF pins(early 4 pins version) :

 

Pin 1 = airflow signal to ECU 1.6V-4.1V

Pin 2 = reference voltage  5 V

Pin 3 = ground

Pin 4 = vehicle voltage 12V

Where can I download or buy ECU Talk software from?

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  • 2 weeks later...

Finally cable arrived last week and I had to send it back to replace it with OBD II type. The idle RPM showed is normal in ECUTalk, 750-80. There is two option in graphic which are similar reading, RPM Pump and RPM. Any idea why idle RPM are different in car and ECUTalk?

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Finally cable arrived last week and I had to send it back to replace it with OBD II type. The idle RPM showed is normal in ECUTalk, 750-80. There is two option in graphic which are similar reading, RPM Pump and RPM. Any idea why idle RPM are different in car and ECUTalk?

Did you try to compare the speeds with fast idle switch as well or does the difference continues across the RPM range?

 

ON mine ECUTalk is reporting about ~200 RPM difference across the range (less) but not at idle.

 

On ZD30 the tacho is directly controlled by ECU so either there is a bad connection, ground or actual tacho problem I'm not sure what the cause would be, unless ZD30 and TD42 use different calibration method for tacho and somehow there is misconfiguration or someone changed the instrument cluster from such vehicle.

 

It could also means that ECU or pump module are reading the RPM speed at idle incorrectly. Normally engine sounds/runs smoothly at idle anything lower it will sound laboring almost feeling like a miss.

 

Regards

Edited by Rumcajs
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Yes  rpm is 1200 with heater switch on in ECUTalk and tacho and matches upward. The only difference is when rpm goes below 1000rpm.

 

Well I have to be patient and slowly check bit by bit until I find the problem. I have been in contact with a mechanic and he suggested to change speed sensor which there is one on right hand side of transfer case. I am checking voltage according to A\T manual.

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  • 6 years later...

Hi all i have a 2004 zd30 patrol an the problem im having with it is that when im driving then engine light comes on an i loss power but i pull over turn it off for a min or two then start it back up it run normal but the the car will do it again but with out the engine light coming on an i do the same thing also it shuts of on its owe when im driving it it idles at 600rpm an by the way it is a full engine rebuild im thinking its a earthing issue but not sure

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Hi,

Checking ground connections would be the first point of call, probably even adding extra earth strap to body would be beneficial.

I'd still extract error code/s to see what is the system is up to. The symptoms described point to injection pump issues.

Regards

 

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