Overboost problem, 2005 Patrol

[andrewk]

so whats an egr run at as i would sooner keep truck stock.

I don't know yet - but hope to on Monday. I *think* I read somewhere that it's over £300. (but also that for a ZD30 in a Vauxhall van, it's ess than £200)

To be honest, I'd rather keep mine stock too - but would be devasted if I installed a new EGR valve and it idin't fix the fault, which is why I'll block the EGR first, at least on an experimental basis.

I'll let you know ..........

Andrew

 

[Timbo_1975]

Put your vacuum gauge into the egr valve and see if the ecu is opening the valve at ~3200rpm.

Or alternatively, pull off the vacuum line to the egr valve and see if the maf reading remains level?

 

[andrewk]

Put your vacuum gauge into the egr valve and see if the ecu is opening the valve at ~3200rpm.

Or alternatively, pull off the vacuum line to the egr valve and see if the maf reading remains level?

This is an August 2005 Patrol with a ZD30. The EGR valve is NOT vacuum controlled. The valve has a stepper motor that controls its operation.

The plan is to block the EGR valve next week and re-do the MAF test to see if the oddity at & above 3200 rpm still exists. If the output volts from the MAF becomes linear up to 4000 rpm (as the manual suggests it should be) then I can be pretty confident that the EGR valve is at fault. If it doesn't become linear then I've no reason to suspect the EGR valve any more.

Andrew

 

[andrewk]

A TIP:

If any of you folks short pins 1 & 8 on the Patrol's 16 pin diagnostics connector to put it into Diagnostics Mode 2 (instead of buying a Consult-Alike) - and if, like me, you've made up a bespoke ODB-II plug containing only the shorting link - then do remember to take it out of the diagnostics socket!!!!

If you leave it in the socket -

* You will not be able to find the shorting plug - not matter how hard you try
* If you drive the Patrol - it will run LIKE A SLUG. You get pretty much zero boost and it'll be flat out at less than 30 mph no matter which gear you try.

FWIW, before I had discovered what was causing the slug-like behaviour, I put it in neutral and increased the engine revs to 3200 rpm. Boost rose to 15 psi. At a touch over 3200 rpm, boost falls to pretty much zero and the ECU posts an 0905 overboost error. It also posts an 0406 MAF error (never seen that before).

Once I'd discovered the plug & cleared the errors, normal performance was restored. No permanent damage, thankfully.

What a plonker!! :doh

P.S. I think the previous owner may have tampered with the adjustment of the VNT rod - I can see a couple of clean threads with no paint on - and the paint on the locknut doesn't quite align with that on the adjuster. It's also possible that the stop screw may have been tampered with.

So, does anyone have any bright ideas about how I might go about checking & re-adjusting the stop screw & rod adjuster from scratch?

I'm tempted to start by adjusting the stop screw until the VNT lever just touches the stop when the vacuum on the actuator is 18 " Hg - and then gradually lengthen the VNT rod (testing regularly) until the overboost error at round about 3300 rpm in neutral goes away. At that stage, I hope it'll be back close to the factory setting - so I can road test & decide whether I need to do anything else to reduce boost at cruise or spiking.

Is that a plan?

Andrew

 

[Jocky]

Hi Andrew, have been reading in the place of the patrol guru's that you are getting somewhere near to sorting out this issue:thumbs

:clap

 

[andrewk]

Hi Andrew, have been reading in the place of the patrol guru's that you are getting somewhere near to sorting out this issue

Yes, indeed.

I did previously have a duff MAP (boost) sensor. This was changed in April 2010 and the Patrol was fine for quite a while. In December, whilst accelerating hard down the sliproad from Haslingden onto the M66, I got the dreaded overboost/limp. It turns out that whoever tampered with the VNT linkage settings didn't bother to re-tighten the grubscrew locknut - so it worked loose over a year or two and caused the overboost error again. I must just be lucky having two causes for the same fault symptom within a year. :lol

For the benefit of others reading this, it is NOT correct (as suggested in a previous post), that a vacuum of around 18 " Hg should be required to pull the VNT lever onto the stop. It might be true for a VW TDi (which may be where I got that notion - VW TDi forum) - but it isn't true for a VNT turbo in a ZD30. A vacuum of 14" Hg applied to the VNT actuator should just trap a 2 thou feeler. In the workshop manual, the spec is for a vacuum of 13.86 +/- 0.39"Hg for a rod stroke (from the top) of 8 thou. As the grub screw is about a quarter way along the lever, this is equivalent to round about 2 thou at the stop.

The current position is that I can no longer cause an 0905 overboost error in neutral at high engine revs. I can still just do so if I'm brutal with the motor at full throttle over 3000 rpm. I have a little more adjustment of both the grub screw and VNT rod adjuster to do, but I'm pretty confident that it'll be fully sorted in a day or two.

Best wishes
Andrew

 

[dinky]

Well Andrew think you should be pleased what you have done and saved lots of money running to dealers,take my hat of to you sir.jd:thumbs

 

[andrewk]

The current position is that I can no longer cause an 0905 overboost error in neutral at high engine revs. I can still just do so if I'm brutal with the motor at full throttle over 3000 rpm. I have a little more adjustment of both the grub screw and VNT rod adjuster to do, but I'm pretty confident that it'll be fully sorted in a day or two.

Mmmm ......... that was a very optimistic take on the current position. I still have the overboost problem at 2500rpm-3000rpm under load at half throttle or more.

I've got myself a laptop, a copy of ECUTalk and an ECUTalk cable which I've had to mod by lopping the 14 pin plug and replacing with a 16-pin OBDII style plug. I'm convinced that I've got the connections (and everything else?) right - but at the moment, it just refuses to connect to the ECU.

I need to find out whether the problem is the diagnostics socket on my Patrol - or the ECUTalk stuff. Do any of you guys have a Nissan (Patrol, Terrano or whatever) that is about the same age as mine (not a CRD), has a 16 pin OBD socket and lives anywhere within 50 miles of Oldham - who fancies checking out ECUTalk on their motor?

Andrew

 

[geoffdown]

Mmmm ......... that was a very optimistic take on the current position. I still have the overboost problem at 2500rpm-3000rpm under load at half throttle or more.

I've got myself a laptop, a copy of ECUTalk and an ECUTalk cable which I've had to mod by lopping the 14 pin plug and replacing with a 16-pin OBDII style plug. I'm convinced that I've got the connections (and everything else?) right - but at the moment, it just refuses to connect to the ECU.

I need to find out whether the problem is the diagnostics socket on my Patrol - or the ECUTalk stuff. Do any of you guys have a Nissan (Patrol, Terrano or whatever) that is about the same age as mine (not a CRD), has a 16 pin OBD socket and lives anywhere within 50 miles of Oldham - who fancies checking out ECUTalk on their motor?

Andrew

i am in the same boat i bought a cable box and downloaded ecutalk and i to cant get it to talk to the ecu have u got ecu to talk to the serial port that the cable is on as i can plug it in and get a green light on the box

 

[andrewk]

i am in the same boat i bought a cable box and downloaded ecutalk and i to cant get it to talk to the ecu have u got ecu to talk to the serial port that the cable is on as i can plug it in and get a green light on the box

What I have is one of these: http://www.ecutalk.com/interface/usbcable.jpg

If I plug the cable into the netbook, it is recognised and the USB serial driver is installed. After connecting to the OBD socket in the Patrol, when I start ECUTalk, it tries to connect to the ECU via COM3 but repeatedly fails.

I don't get a green light anywhere. I've had the cover off the box at the USB end of the ECUtalk cable - and can't see a LED. Do you have a different cable?

Andrew

 

[andrewk]

A minor move forwards on this and a potential solution to (one of) my problem(s). The connection diagram for the 16-pin OBDII socket from ECUTalk is: http://www.ecutalk.com/images/OBDII.jpg It shows the ground (earth) connection as pin 5. The circuit diagram on page EC-4037 of the dealer workshop manual shows pin 4 as being the ground/earth connection. I'll resolder it later today and try again.

Andrew

 

[geoffdown]

What I have is one of these: http://www.ecutalk.com/interface/usbcable.jpg

If I plug the cable into the netbook, it is recognised and the USB serial driver is installed. After connecting to the OBD socket in the Patrol, when I start ECUTalk, it tries to connect to the ECU via COM3 but repeatedly fails.

I don't get a green light anywhere. I've had the cover off the box at the USB end of the ECUtalk cable - and can't see a LED. Do you have a different cable?

Andrew

i have this http://cgi.ebay.co.uk/Nissan-Consul...iagnostic_Tools_Equipment&hash=item43a70f92b9 and i can get ecutalk to connect to the com port it keeps saying failed retry in 5 secs is that what u get

 

[andrewk]

i have this http://cgi.ebay.co.uk/Nissan-Consul...iagnostic_Tools_Equipment&hash=item43a70f92b9 and i can get ecutalk to connect to the com port it keeps saying failed retry in 5 secs is that what u get

Ah, that's why I don't see a green light. :thumbs

Yes, at the moment, ECUTalk keeps trying to connect to the com port, fails & retries after 5 secs. It just repeats that.

My 16-pin plug being wired wrongly might explain my problem - but it doesn't explain yours. Do you have the .NET 1.1 framework installed (as it says you should on the ECUTalk website?)

Andrew

 

[geoffdown]

Ah, that's why I don't see a green light. :thumbs

Yes, at the moment, ECUTalk keeps trying to connect to the com port, fails & retries after 5 secs. It just repeats that.

My 16-pin plug being wired wrongly might explain my problem - but it doesn't explain yours. Do you have the .NET 1.1 framework installed (as it says you should on the ECUTalk website?)

Andrew

yes it installed on my win98 laptop which is kept for other cars in the house:doh i to had to convert the pin from 14 to the 16 pin

 

[andrewk]

i to had to convert the pin from 14 to the 16 pin

Did you wire it like this (per ECUTalk instruction) ....

or like this (workshop manual for Patrol with ZD30).........

Note where ground is connected to

Best of luck
Andrew

 

[andrewk]

I've had another look at the diagram in the manual. Pin 5 is also connected to ground - so iot shouldn't make any difference which is used.

Ho hum .......

Andrew

 

[Dartmoor_Lad]

Mate of mine hasd a similar problem in his old saab, turned out to be a problem with the wastegate sticking

 

[andrewk]

The turbocharger in a ZD30 Patrol engine doesn't have a wastegate. The turbo has a set of vanes that are moved by a vacuum operated VNT actuator and they can stick if they are gummed up - but that definitely isn't the problem with mine.

Andrew

 

[andrewk]

Just to let you guys know that I'm throwing in the towel on this overboost business. I've got the turbo VNT adjusted as best I can, but it still overboosts above 2500 rpm under load on large throttle - about 18 psi and ping, there is goes

No, I'm not getting rid of the Patrol - nor am I going to throw money at Nissan (how much would be new ECU and a new turbo cost anyway - thousands, I guess). The throwing in the towel involves buying a Dawes valve and fitting that. It costs about £30 and will take me about half an hour to fit. I'll adjust it to start to crack open at 15 psi and hopefully, the problem will go away.

I would have said "problem solved" - but it isn't. All I'm doing is treating the symptoms, papering over cracks, sweeping stuff under the carpet. I still don't fully understand what the true *cause* of the problem is and may never do - but like the rest of you, I have a life to live that doesn't involve fiddling around under the bonnet of a recalcitrant Nissan Patrol.

All the best .......
Andrew

 

[Thomas-the-Terrano2]

just remembered that last year my rac pal couldnt get his works lappy to connect
to troll and he had various software, ended up reading codes with the wire method
and counting mil light flashes.

mind mine is fair bit older than Andrews.

mine has been behaving lately, though did get it to light the mil other
day, under usual conditions.

Andrew, I think you deserve a medal for thre research you've done just
pity as said are having to compromise for sake of sanity!

please post some pictures of the dawes valve conversion.