Overboost issue post Dawes Valve and catch can fitment.

[wranga]

Long story short. 2000 ZD30 went in for a tune and came out with new engine when a cylinder was found to be weak. New motor was left stock until warranty ran out. Had a Dawes Valve and a Catch can fitted and now the workshop can only set Max Boost to 10psi and it still has an overboost problem. Will go into limp mode in 4th and 5th gear 23-2450rpm under moderate acceleration blip the throttle and it rectifies itself. Egt's are running no higher than 450-500° running at 105kph uphill. This motor has a Redback 3"straight through exhaust and a larger intercooler which were fitted prior to replacement engine with no overboost issues. Workshop never fit a EGR blanking plate as I'm only going to do 15-20,000km before moving the vehicle on and they have had issues with ZD30 over boosting with a blank plate fitted. Apart from the overboost issues Dawes control for the turbo has made the vehicle much nicer to drive. Pre dawes my boost was all over the shop with erractic and potentually dangerous EGTS (600+°). What could be causing this boost issue??? Workshop says my vehicle is worst they have seen. Normally they set max boost at 14-15psi post dawes fitment without an issue. Mine is set at max of 10psi and still has issues? Hope my rambling makes sense any help is greatly appreciated. The workshop is talking about fitting a "fuel cut defender" for extra cost of course to sort out this issue.
Cheers guys.

[BigRAWesty]

What condition is the maf sensor in?

[mudski]

As westy has said. See if you can swap out the air flow meter for a test. Could be a dud. Do you have a needle valve fitted? Has the dawes been correctly installed too? Check for boost leaks aswell, the intercooler on these are prone to leaking too. Not that a boost leak should cause limp issues but its worth a check.
You should atleast get 15-17psi before limp mode kicks in. A needle valve will help a lot with controlling the spool up rate of the turbo which can also cause limp mode issues. Because the turbo, without the needle valve, could be spooling up too fast, giving a false sense of over boosting even when it hasn't reached is actual limit. So with the needle valve you can increase or decrease this rate and get the maximum performance out of the turbo and you will be able to fine tune the turbo to suit.
Also, in my opinion, fit a EGR plate, it takes a whole 10 minutes to do, the car will run better to and you wont see any over boost issues with the valves in. As this is what they are designed to do, stop over boost and hitting limp mode.

[threedogs]

Something is up that's for sure, disconnect the battery prior to any new work being done.
It {ECU} may be remembering old values.
NOTE:: even a new MAF may be faulty, swap with a mate if you have one with a Di motor.
Who set the dawes up?? The overboosting with the EGR plate in was mainly with the CRD not the Di

[wranga]

Can MAF be tested ie resistance??
No leaks in intercooler as its solid welded and have checked all fittings. No needle valve that i know of turbo still has the Variable Vane hooked up. Will try get a pic of the turbo and "dawes" valve they have fitted. Workshop that fitted parts up was LMG at warnertown in South Aust. Mate who is a Caterpillar mechanic said some people have talked about disabling the "swirl" butterfly but ye wasn't sure what that entails?? Need to get it sorted as i have a cranky wife after dropping 14k on a new engine. Seems odd that overboost issue has only arisen since dawes and catch can have been fitted.

[threedogs]

You might want to get your hands on an ECU-Talk.
I think the MAF shuts downs when it reaches 4omhs

[wranga]

Ok guys spoke to the workshop that fitted the valve and catch can. Not a dawes fitted but a boost controller from HDP designed for Variable Turbos. It has 3 not 2 outlets so no need for needle valve apparently. Next step for them is to fit Fuel Cut defender to electronically "trick" the ecu into thinking all is fine. Will try swap out MAF with another one and disconnect battery overnight on off chance that sorts it out. Workshop believes once fuel cut defender is dialled in we can set boost where we like. Will also fit EGR block. Cheers

[NinjaJason]

I had some issues with limp mode after my radiator blew.
Took a while to figure out the MAF sensor had been contaminated with coolant and was faulty.
Once a new one was fitted - problem solved. Don't bother ringing Nissan as they will sell you a complete assy for about $800 bucks.
I got a factory equivalent of Ebay for a lot less.
Also if you don't have a needle valve then the spool up rate will be too high unless you adjust the turbo actuator arm. But then you don't get the maximum performance from the turbo.
Just make sure when the Dawes Valve was fitted that they bypassed the VNT solenoid.
here is a handy link http://www.chaz.yellowfoot.org/Manua...Controller.htm

[threedogs]

Not sure on that fuel cut thingy, A Dawes valve is a manual boost controller with 3 outlets
Check this diagram to see if you have fitted yours correctly, this Chaz is a Guru on all
things ZD30 related.
http://www.chaz.yellowfoot.org/Manua...Controller.htm

@mudski

[mudski]

Can MAF be tested ie resistance??
No leaks in intercooler as its solid welded and have checked all fittings. No needle valve that i know of turbo still has the Variable Vane hooked up. Will try get a pic of the turbo and "dawes" valve they have fitted. Workshop that fitted parts up was LMG at warnertown in South Aust. Mate who is a Caterpillar mechanic said some people have talked about disabling the "swirl" butterfly but ye wasn't sure what that entails?? Need to get it sorted as i have a cranky wife after dropping 14k on a new engine. Seems odd that overboost issue has only arisen since dawes and catch can have been fitted.

Get a pic of the Valve thats used and how its plumbed in.... Three ports is correct, one for boost pick up, and the other two simply just T into the vac line going to the turbo from the control solenoid next to the air cleaner. As for swirl valve. Don't bother. You wont see any difference in anything. If your curious though, just disconnect the vac line that runs to it, the butterfly will stay open then, and go for a drive. Swap out the air flow meter too if you can. Disconnect the battery for 15 minutes, reconnect and go.

I had some issues with limp mode after my radiator blew.
Took a while to figure out the MAF sensor had been contaminated with coolant and was faulty.
Once a new one was fitted - problem solved. Don't bother ringing Nissan as they will sell you a complete assy for about $800 bucks.
I got a factory equivalent of Ebay for a lot less.
Also if you don't have a needle valve then the spool up rate will be too high unless you adjust the turbo actuator arm. But then you don't get the maximum performance from the turbo.
Just make sure when the Dawes Valve was fitted that they bypassed the VNT solenoid.
here is a handy link http://www.chaz.yellowfoot.org/Manua...Controller.htm

Dont ever adjust the actuator arm unless you know what your doing. Screw this up and you will be in a world of more pain from the missus for making things worse. This is why a needle valve is used. Easy to install, easy to adjust.
Also if your just fitting a Dawes, you don't bypass the solenoid, it must still use this, to control the spool up rate. If you run a needle valve with the dawes then yes, you by pass the solenoid.

And you can buy OEM MAFs for well under $200 too. 22680-AD210 is the part number. Just be careful, there is a mob on eBay selling aftermarket mafs as OEM for under $100. They've even gone to the effort to make up OEM stickers. Which don't look right and the box they use is not how Nissan package it....

Make sure they have the Dawes tee'd into the vac line from the middle port of the solenoid too...