ZD30 engine safety featre

[big_fletch]

I saw a question about power loss on the zd30 motor, so just for the people that are not aware the 3.0 motor has a boost safety feature built into the computer (I believe it was introduced into the late 2001 models after so many motors had problems in 2000-2001)..
When boost is to high for to long the computer cuts power to the motor and the accelerator pedal becomes dead, this prevents damage to the engine..
When the accelerator pedal is completely released then power is restored and vehicle runs normal again, you are free to accelerate (basically foot off and back on)

Just thought I would post this up, might save someone from replacing sensors and spending their hard earned cash on something that's not a problem..

Fletcha

[Sir Roofy]

very interesting ill keep that in mind for future reference

[ashbee37]

have a problem with my auto 3ltr. when accelerating, gets to around 3grand and then stops accelerating egts, boost stays the same, no Eng lights. lift my foot and reapply and all is fine till next time. could be maf or tps by my guess but wanted to make sure what it is as haven't got the dosh to wast, so took to local diesel mechanic to diagnose but when he hooked up his computer it could not read the CPU. anybody got a clue whats going on and why he cant talk to the comp, he said i would have to take it to Nissan to find out why
not maf, changed it and still the same, well not quite the same. now ive got more problems after reconecting battery after having it off for 24hrs, now the alternator was dead so i had to get a new one and when taking well trying to take drive belt of the tensioner was at a 45deg angle so, new one of them and while reading manual i saw that its recommended you change timing chain every 100thou so seeing its just clocked over 200thou and don't know when it was changed last well,dash lights are on, sub tank, at temp, seatbelt, handbreaK and alt lights are all light
the alternator was dead so i had to get a new one and when taking well trying to take drive belt of the tensioner was at a 45deg angle so, new one of them and while reading manual i saw that its recommended you change timing chain every 100thou so seeing its just clocked over 200thou and don't know when it was changed last well,after new alt, timing chain, tensioner, hoses ect. i also started putting catch can in but did not realize one of the fittings was blocked, well when i started motor ran for a couple of minutes then stalled, heap of white smoke. worked out it was the blow bye that built up and stalled it. fine disconnected the catch can and motor started fine and smoke went away. now runs fine but now on the idle sits on 45 instead of 24 warm or cold plus i think the running pressures are higher will note tomorrow and post. plus i think there may be more blow bye now.

so can anybody tell me what damage i may have done now. and bye the way still got the original problem just comes in different times depending on needle valve setting

[Lieney]

I have the same problem with the engine cutting out under load about 3500rpm. Release foot and re-apply, power is returned.
#A diesel place#
said it was a pinched vacuum line under the plastic cover. No fault codes appeared. cost me $90 for them to check it.
Problem occurred again today but worse. I checked it and the only possibility would be the dawes valve fitted by them. Nothing else is any where near it.
On thread stated an earth strap on engine can cause issues, but not sure if this is our problem as I haven't checked it.
Please let me know if you find out what it is as I really need to know. I'll do the same if I find out.
I had relax plans tonight but I guess I will be tinkering instead.

[threedogs]

Clean the MAF sensor just to left of aircleaner, need torx bits to remove
Is yours Di or Cr????
Really need to fit boost guages to the Z30 motors, and EGT man hasta know whats going on.

[Lieney]

Boost limited at 17psi.
Engine Di not comin rail.
Had MAF out few months back & spotless.
Have all the tools so will do that again & check it.
I want a wiring diagram with all the specs so I can test & play but cant get one off
Nissan

[the evil twin]

Ashbee... pls excuse the lack of the quote as your post is a tad big...

The reason he can't read the ECU is that prior to the CRD's the Patrols aren't full OBDII compliant. Thats why Scanguages will work on ZD30 CRDs etc but not on the ZD30 Di or TD42's. You need either Nissan Consult or "ECU talk" software.

As big fletch mentions a huge amount of the limp mode issues are boost related. There are some threads on here detailing how to check the TPS and if that is OK then I'd try dialing back the boost a tad. Altho there are some other issues in your post that need attention as well and may be confusing the symptoms and the causes so just work thru them and see how you go.

[Rumcajs]

Boost limited at 17psi.
Engine Di not comin rail.
Had MAF out few months back & spotless.
Have all the tools so will do that again & check it.
I want a wiring diagram with all the specs so I can test & play but cant get one off
Nissan

17 psi limit is too high as on GU IV Di ECU will go in to limp mode at around 18 psi and if you have Dawes set at 17 that means that there will be a spike past 18 momentarily which under right circumstances will cause limp mode.

I have set mine (Dawes) to 15 psi and have no more limp issues. There isn't really any advantage to go higher TBH. Indeed I found that fuel consumption increase particularly at cruise 100-110 km/h is especially hurting the valet. I have the second Dawes to fit so I can have 2 stage boost control, low (8 psi) for economy and high (14 psi) for power run.
Cheers

[threedogs]

Rumcajs, can you explain how lower boost will increase fuel economy, all I can see is it increasing EGTs
Got me beat this one, heard it a few times now

[Rumcajs]

Rumcajs, can you explain how lower boost will increase fuel economy, all I can see is it increasing EGTs
Got me beat this one, heard it a few times now

In simple terms; more boost = more fuel, if you restrict amount of boost the ECU's "smoke map" will restrict amount of fuel. There is a relationship between amount of boost and amount of fuel the so called AFR (air fuel ratio) which affects the whole system subject to engine load, of course EGTs will be higher but we aren't talking 500° C. I will have this system automated to work of the "loud pedal" percentage but still have manual over ride.

I have noted fuel consumption drop by lowering the Dawes limit from 17 psi down to 14 psi by as much as 1.0 L alone while EGTs only increased marginally ( I do have needle valve as well). I also noted a weird thing when first installed Dawes and went for a drive without adjusting anything (it was set to 7 psi) and the whole experience was for very smooth persistent acceleration and cruise except it didn't want to climb the hills that well.

GU IVs are funny beasts in this case. I don't think personally that high boost is really an answer for everything ZD30 performance/EGTs related.
Cheers