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Double post.
I have found that nearly everyone that has a GU 3.0, other than grenade issues, can have similar faults but require different solutions.
I cleaned MAF & repaired a split vacuum hose on a switch located under the engine cover. Good for a while but once driven an hour or so,problems again.
Ive thought about bypassing the butterfly in the inlet manifold to stop it restricting air flow but not sure what exactly triggers it's operation.
I might also adjust the Dawes valve tomorrow & lower the boost a notch or two.
Does engine light come on when safe mode kicks in?
Easier with a "normal" diesel.
Well I adjusted the Dawes valve down a smidge so she's running about 15psi. I also cable-tied the butterfly back. Short run in second worked a treat but a good road run should determine if it's fixed.
Don't think it was boost at 17psi as it was running quite well until recently.
The butterfly is another issue.
By butterfly do you mean throttle body at back of the motor??
You may find that 1-2 psi makes a huge difference with over boost issues.
Pain in the butt but I drove around with 2 spanners and adjusted DAWES as I
drove around, frisky as now, Don't try and obtain more boost it wont work like that.
I was reading all the time 15 psi so was trying to get 18 psi as still safe, aint gunna happen.
goes better smoother quicker and boost just touches 15 psi, nipped up the Dawes, thats it.
NO TWO ARE THE SAME. Also EGTs are great now too.
Cheers threedogs. I didn't seem to have an issue running 17psi until a month or two ago.
I fitted a 3" exhaust, then I had EGR blocked, Dawes installed and then Dyno fitted before Simpson desert trip.
The engine torque died after gear change but car had done this since I bought it.
The butterfly does look like it would be a throttle; however, I don't believe it is exactly that as diesel engines use fuel metering as throttle, as apposed to petrol.
Although in later diesel I have found more and more differences with computer controlled nightmares.
I discussed my issues with a bloke at the 4x4, camping & fishing show Sunday who sells all the latest and greatest power increasing products.
He said the 'throttle' is controlled by the ECU and assists in preventing overboost by restricting air flow, getting a signal from computer, amongst many other things that occur.
I checked how it operated and found it was vacuum opened, spring closed.
I cable-tied it in the open position and adjusted the boost down to about 15psi so engine would get unrestricted air, and computer would do its thing.
Engine ran real smooth, boost guage didn't push upward of about 18-19 and there was no lag in gear change as previous.
I will increase boost again a smidge and see what happens.
Happy with outcome so far.
Need to block off the vacuum solenoid, block egr. Thats all I've done plus fit Dawes and needle valve under bonnet,
You need to read Chaz Yellowfoot {guru} on Z30 via search engine. don't think 18 is better 15, doen't work like that.
By doing all these things you take the thinking away from computer and controll it yourself, When you do adjustments disconnect battery for 1 hr or so
as well, Whats Dyno fitted??? Just doesn't sound right, or I'm missing something
There are two "butterflies" in there, the one closer to bulkhead is the so called swirl control valve and its precise nature is according to Nissan; to generate better airflow swirl in to cylinders and its suppose to only work at low RPM (up to 1200). I believe personally ( I have no proof but on other small Diesels it is used for that) that this valve is/can be used for additional EGR control to assist with reducing intake air pressure to allow exhaust gases to get in. This one can be safely disabled as it suppose to have no net effect. Not really there to control overboost as such! It is actually EGR which is used to some degree to deal with overboost. Some experts ay.Quote:
Originally Posted by Lieney
The other(closer to the front of the engine in the main part of the Y piece) one is an engine stop "strangler" it is activated when engine is turned off to assist the engine shutdown. Don't disable that one!
Is yours by any chance with auto tranny? On those the way to reduce chance of overboosting induced limp mode even with Dawes is to actually adjust the VNT stop screw to reduce/limit the rate of turbo spool. Apparently it is desirable to do it and the results can be very beneficial.
On manual tranny it isn't that crucial as with every gear change the revs will drop to idle so the turbo needs to pick up again whereas with auto you've already spooled the turbo with RPMs up and when gear change happens with out them really dropping off back to idle it is easier to overboost, you'll get an idea.
15 psi is plenty pushing to 18 is asking for trouble and further action is required like the VNT stop screw adjustment.
Cheers
No, you are not missing something. I miss-typed.Quote:
Originally Posted by threedogs
I had the dawes valve fitted and then had a Dyno test done.
I could not get any decent information on exactly how the vacuum system in this engine actually worked, so was a little scaredI was going to destroy something.
LOL - typo. I do that sometimes
Rumcajs
I was unaware there was another butterfly. I might just have a little look when I get more time, and it warms up. Freezing tonight.
One causes turbulance ay? It used to stall the turbo, but now i got it held open, the stall seems minimal and engine acceleration is smooth as
I had all this apart when replacing my turbo. Would have been a good time to investigate if I wasn't in a rush.
Its a manual, until I get my hands on an LS3 and adapter kit, maybe. :)
Thanks again