3 litre Diesel EGR valve block off

[Owen Douglas]

I have just read some very good information on contamination of the MAF sensor causing false readings to the ECU and resulting in overfueling in some cylinders and eventual piston damage. Options for correction included a "catch can" or blocking off the EGR altogether and fitting a manual "Dawes" control unit.

Reducing Exhaust Gas Temperatures appears to be the main issue for prevention of engine failure &/or increasing longetivity.

This leads to other questions such as does chipping this motor lead to higher EGT's?
I have also heard the increasing exhaust size will overrun the turbo which will eventually fail through lack of oil supply.

The "economics" of engine "add ons" for improved fuel economy/performance needs to be balanced with the cost of expensive engine replacement. I am therefore after comments on this issue and specifically if there is an "expert" in Queensland who is experienced with fitting the Dawes unit & related modifications.

[growler2058]

G'day mate welcome aboard they're a good mob here full of useful info and advice! Ynot will most likely have some answers for ya mate. While ya waiting jump over to the intro page n tell us a bit about u n ur troll We love foters here to mate so chuck em up if ya got

Haha look if I read properly it is in intros hahaha mayb try the mech section as alot of members don't read the intros:-) still if ya got foters......

[YNOT]

Welcome to the forum Owen.

"I have just read some very good information on contamination of the MAF sensor causing false readings to the ECU and resulting in overfueling in some cylinders and eventual piston damage. Options for correction included a "catch can" or blocking off the EGR altogether and fitting a manual "Dawes" control unit." If you haven't already, have a look at this thread; http://www.nissanpatrol.com.au/forums/showthread.php?4421-Caring-for-your-diesel&highlight=gren02


"Reducing Exhaust Gas Temperatures appears to be the main issue for prevention of engine failure &/or increasing longetivity." Correct

"This leads to other questions such as does chipping this motor lead to higher EGT's? " Not if the chip is properly programmed. A properly programmed chip will not rely soley on extra fuel to make extra power but will adjust other parameters such as injection timing and boost to get more power while still keeping the EGT's within safe limits. There is also an Australian made chip sold under the "Chip It" banner that includes it's own EGT sensor and reduces fuel if it see's excessive EGT's, something to consider.

"I have also heard the increasing exhaust size will overrun the turbo which will eventually fail through lack of oil supply." Fitting a bigger exhaust can cause overboost issues on these engines but it can be controlled by either fitting a Dawes/needle set up or adjusting the boost limiting grub screw on the turbo. An overboosting turbo can also damage the intercooler.

"The "economics" of engine "add ons" for improved fuel economy/performance needs to be balanced with the cost of expensive engine replacement. I am therefore after comments on this issue and specifically if there is an "expert" in Queensland who is experienced with fitting the Dawes unit & related modifications." The only workshop that I know of personally that fits an engine saver kit to ZD30's is Brisbane Turbo and Tuning Centre.
Where about's in this fine state of QLD are you?

Tony

[Owen Douglas]

Thanks Tony. I'm in Toowoomba so Brisbane is fine. Sounds like you know what you're talking about - might need to contact you again.

[Woof]

Hey Owen, just moved your post to this section as not everyone reads the introduction section, can you please post up an intro in the intro section again with just a bit of info about yourself, where you live and of course you Patrol, thanks mate

[YNOT]

Thanks Tony. I'm in Toowoomba so Brisbane is fine. Sounds like you know what you're talking about - might need to contact you again.

There's been some frosty mornings in Toowoomba lately.
Ask any questions you want, we're here to help. I have a GU3 3lt and have done the engine saver mods to it.

Tony

[Yendor]

Hi Owen, and welcome to the forum.

Yes the first thing I would do (did) is fit a catch can, this is the easiest and will not cause over boosting or any other problems.

Then I would get a boost gauge and pyrometer fitted (EGT gauge).

I had my chip (Steinbauer) and 3" exhaust fitted by Motsons, I am guessing they adjusted the boost grub screw because I never had an over boosting problem.

But yes I found with the chip fitted I could easily get very high EGT's.

After blocking the EGR and fitting Dawes my EGT's run much lower.

Cheers Rodney

[DrHarry]

Having read lots on the forums about all these topics, one question that I keep coming back to is this. In the effort to control overboost after bocking EGR and fitting a 2.5' mandrel exhaust should/can I:
1) Fit Dawes valve
2) Fit Dawes valve plus needle valve
3) Fit needle valve only
4) Adjust VNT screw
5) All of the above?

My GU is a 2008 CRD (with gas) and despite many folks thinking that these are less prone to erratic boosting mine is now regularly hitting 20. This isn't enough to put up a code but I believe it is too much? How much is too much? How worried should I be?

I gather I should be aiming for <15psi consistently?

Also my EGT is tipping 700 at times on the open road. Hopefully the drop in boost I seek will also help this?

Thanks knowledgable ones!

Harry

[Gert B Frobe]

DrHarry,

Where is your probe situated for your pyro? If it is downstream of the turbo temps should be lower but if its in the manifold they will be higher. My experience has been in marine diesels so big engines and the pyros are fitted pretty much directly after the head, but engines of this size have the room to place probes in optimum positions. The only "downfall" to placing the probe in the exhaust pipng is it will read an "average" temp across the cylinders. The manifolds on small capacity diesels can be very difficult to place sensors for accurate readings.

Just my two cents

[DrHarry]

It's in the dump pipe after the turbo I believe, as it was installed with the exhaust. Excuse my ignorance I thought that's where they all are?

I better have a closer look!

[YNOT]

Having read lots on the forums about all these topics, one question that I keep coming back to is this. In the effort to control overboost after bocking EGR and fitting a 2.5' mandrel exhaust should/can I:
1) Fit Dawes valve
2) Fit Dawes valve plus needle valve
3) Fit needle valve only
4) Adjust VNT screw
5) All of the above?

My GU is a 2008 CRD (with gas) and despite many folks thinking that these are less prone to erratic boosting mine is now regularly hitting 20. This isn't enough to put up a code but I believe it is too much? How much is too much? How worried should I be?

I gather I should be aiming for <15psi consistently?

Also my EGT is tipping 700 at times on the open road. Hopefully the drop in boost I seek will also help this?

Thanks knowledgable ones!

Harry

The first thing I will say is I have never worked on a ZD30 CRD so this information is assuming the VNT turbo setup is the same as the DI motors.

There is a couple of different ways to control the boost
1) Adjust the boost limiting grub screw. By my way of thinking not ideal as it may also slow the rate of spool.

2) Fitting a dawes valve on its own in conjuction with the factory boost control. This still gives the engine computer control of the boost but eliminates overboosting. This is a good method if you want to keep a functioning EGR system as it lets the computer reduce boost to allow the EGR to work.
6548

3) Fitting a single stage dawes and needle set up. This gives full manual boost control, the computer is no longer in control of boost. The dawes sets the maximum boost and the needle valve contols the rate of spool.
6549

If your post turbo EGT's are hitting 700 you need to be lifting off the accelerator, those temps are WAY to high. Don't let the EGT's get over 550.
Reducing boost will make the problem worse, diesels run hot when they are rich - the opposite to petrol engines. You need to be aiming for a constant 17Psi boost not the erratic boost you are currently experiencing.

Tony

Thanks to CHAZ for the images.

[DrHarry]

Many thanks Tony. I am just waiting for my Dawes valve. Not too sure why my EGTs are so high (although I have only noticed it head up towards 700 once, and I certainly backed off quick smart!).

Wonder if the gas is the confusing factor for my wagon.

Harry

[DrHarry]

I fitted the valve yesterday...took about 5 mins. Disconnected the boost controller on the vehicle as suggested by the guys at Opposite Lock (who sold me a nice version of the Dawes which can be adjusted without disconnecting it).

I am happy! Max boost has been 13-14 although I did glimpse one reading of 16. The boost seems to increase in a linear fashion with the application of right foot. Boost alarm has been blissfully quiet. I'll let you know how it went next week after a country/bush run. Will also report on EGTs.

Interestingly the turbo whistle that was very loud (after you take you foot off throttle when changing gears) has now disappeared. Was that noise from the wastegate due to over boost I wonder? Shame really, it sounded quite sexy!

Conclusion...CRD Patrols may still benefit from a Dawes valve after EGR block and exhaust upgrade.

Harry

[YNOT]

Glad to hear you got it sorted.

Would you be able to post a photo of the valve you fitted please, it may benefit other members.

Not sure about your turbo noise, VNT turbo's don't have a wastegate.

Tony

[DrHarry]

Glad to hear you got it sorted.

Would you be able to post a photo of the valve you fitted please, it may benefit other members.

Not sure about your turbo noise, VNT turbo's don't have a wastegate.

Tony

Here is the "Dawes" valve as sold to me by Opposite Lock. It is adjustable with the hex screw on the end, and a locking nut is on top of that. In the picture it is screwed all the way in giving a max boost of about 14-15...seems just right. Unscrewing decreases max boost, brings back that whistle and sends my EGTs up higher.

The brand on the other side of the valve is "ASE".

Cheers
Harry

[Scabad]

DR Harry I would be interested to hear how much increase performance you have expereinced from the diesel gas installation. When I was speaking with Taipan thhey suggested that you would be looking at another 15-20% performance increase. Balanced with that the boys at Berrima Diesel indicated experience with pre ignition issues with some gas systems with the gas/air mixture igniting prior to the injection of the diesel with a few cases of engine brewing up. Be interested with your experiences.

Cheers

Scabad