EGR Blank causing limp mode

I've been trying to search the forum with no luck to see if anyone else had this issue.

I recently installed a dawes valve kit, erg blank and 3" exhaust. When driving at highway speeds with a steady pedal the Patrol would go into a "temp" limp mode. After coming off the pedal for a sec and back on it would go just fine. Through investigating I noted the boost would come up to quickly for the Dawes kit compensate but it would still occur. It was only after removing the blanking plate would the valve kit work correctly.

The blanking plate that I purchased did not have the hole as I had seen in others, but based on the position the instructions indicated for it install it didn't cause the dummy light to come on, so thought all is good.

Any ideas as to what is causing this? I currently to not have blanking plate in and would like to put it back. Should I put a hole in it to allow some recirculation?

Bump...........

sorry Ozmerican...... as you know, mines a 4.2
so I wouldn't know shyte from clay with a 3.0.......

hopefully someone like Nizzbits can help? maybe....?

I've heard if it's a crd zd30 you need the hole drilled in or a scan guage to stop limp modes

Try backing the dawes off a bit at a time sounds like your a tad of the sweet spot

Whats your max boost reaching ?
DO what I did and put a permanent texta mark on the dawes.
Grab a pad and pen, adjust your boost,noting what you did.
If its hitting 15PSI if thats your max quickly,,,,, open the needle 1/2 a turn writing it down.
Takes a little while but you'll get there, grab two spanners and go for a drive

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Originally Posted by macca86

I've heard if it's a crd zd30 you need the hole drilled in or a scan guage to stop limp modes

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Nah, blanking plate EGR codes on the CRD's only set the check engine light.
They won't cause limp mode so drilling the hole or clearing the fault is only to stop the check engine light.


As posted by Roofy I think the problem is the Dawes and Needle needs tweaking.

Do you have gauges fitted???

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Originally Posted by the evil twin

Nah, blanking plate EGR codes on the CRD's only set the check engine light.
They won't cause limp mode so drilling the hole or clearing the fault is only to stop the check engine light.


As posted by Roofy I think the problem is the Dawes and Needle needs tweaking.

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there is no mention of a needle valve so if there isnt one you need one to adjust up the spool rate so pm mudski for that or the evil twin has a different way to adjust the turbo actuator so ask him for his knowledge on the subject

No mention of what his max boost is too. Need to know this before you do anything. But my guess is a needle valve would be handing here to help drop the cruising boost pressures. Not only does the needle valve adjust spool up rate, it in turns increases or decreases your cruising boost pressure.

Thanks all. Had a chat with ET at the last club meeting and based on the discussion I need to do a bit more adjustment on the needle valve. As soon as I get back from this work trip going to work getting to adjusted correctly.

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Originally Posted by threedogs

Do you have gauges fitted???

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Yep gauges are fitted.

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Originally Posted by Ozmerican

Thanks all. Had a chat with ET at the last club meeting and based on the discussion I need to do a bit more adjustment on the needle valve. As soon as I get back from this work trip going to work getting to adjusted correctly.

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Ok you have a needle valve then. Open the valve up a little at a time. What is your max boost set at?

I just sussed mine out I believe. I closed the needle valve the opened it untill the turbo acuator arm moved and hit the end off its stroke then a bit back of it. Then set the dawes valve to 15psi. Sweet spot is 10psi under 2000rpm and 15psi at 3000rpm. To achieve that you play with needle valve little bit by little bit.

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Originally Posted by kyle86

I just sussed mine out I believe. I closed the needle valve the opened it untill the turbo acuator arm moved and hit the end off its stroke then a bit back of it. Then set the dawes valve to 15psi. Sweet spot is 10psi under 2000rpm and 15psi at 3000rpm. To achieve that you play with needle valve little bit by little bit.

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Sounds like your on the money there mate. Kudos....

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Originally Posted by Ozmerican

I've been trying to search the forum with no luck to see if anyone else had this issue.

I recently installed a dawes valve kit, erg blank and 3" exhaust. When driving at highway speeds with a steady pedal the Patrol would go into a "temp" limp mode. After coming off the pedal for a sec and back on it would go just fine. Through investigating I noted the boost would come up to quickly for the Dawes kit compensate but it would still occur. It was only after removing the blanking plate would the valve kit work correctly.

The blanking plate that I purchased did not have the hole as I had seen in others, but based on the position the instructions indicated for it install it didn't cause the dummy light to come on, so thought all is good.

Any ideas as to what is causing this? I currently to not have blanking plate in and would like to put it back. Should I put a hole in it to allow some recirculation?

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I have the same issue, AND I had the Dawes and needle valve working what seemed ok. Issue came after the plate was installed.
It seems the boost must be arriving too early and too hard. Do I adjust the needle valve SLOWLY and see what happens.
My high boost Dawes is about 20psi--too high methinks. Comments please

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Originally Posted by Dr Gary

I have the same issue, AND I had the Dawes and needle valve working what seemed ok. Issue came after the plate was installed.
It seems the boost must be arriving too early and too hard. Do I adjust the needle valve SLOWLY and see what happens.
My high boost Dawes is about 20psi--too high methinks. Comments please

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Your running a twin Dawes setup. I would go higher. Mines been running at 25psi for well over 12month now.... But thats how I have it. Some would say its too high. Some not. But it goes alright, for a ZD, and have had zero issues with it so far, touch wood...
whats your low boost set at?

Hi Mudski (and all) I have low boost at 11 psi--a little higher than I would like, but a bitch to get to for a 1 pound reduction, and no limp issues. High has been 22, then 17 then 20. At 17 no issue, at 22 limp easily, at 20 limp at high end--4000 rpm.
I did open the needle valve 2/10 of a turn (it has 10 indicator marks), and that stopped limp at 17, still get it at 20. I will try 18 psi, and maybe one more "click open on the needle valve and report back. I will try needle valve first.
This is very much "try and test", but the truck certainly benefits from fitted needle valve--lag basically gone and spool rate maybe a little quick.
BTW my electronic switch failed (my bad) so I have manual high or low.

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Originally Posted by mudski

Your running a twin Dawes setup. I would go higher. Mines been running at 25psi for well over 12month now.... But thats how I have it. Some would say its too high. Some not. But it goes alright, for a ZD, and have had zero issues with it so far, touch wood...
whats your low boost set at?

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Save your coin and get the HPD high flow maf housing and air box lid. No need to worry about limp mode ever again. My boost gauge is to 30psi. Just as a test I wound the dawes right in. I had the needle on the boost gauge off the clock and I still saw no limp mode. But the engine light came on... jeez it went though.

... are their Boost Controllers any good Mudski?

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Originally Posted by mudski

Save your coin and get the HPD high flow maf housing and air box lid. No need to worry about limp mode ever again. My boost gauge is to 30psi. Just as a test I wound the dawes right in. I had the needle on the boost gauge off the clock and I still saw no limp mode. But the engine light came on... jeez it went though.

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Done the same as above, always had some form of limp no matter what I done as in would be good for awhile but then a random limp now and then, would be good then a cold evening and then limp at 3000rpm ect or upon harder than normal acceleration and limp on gear change, ended up doing my head in, put HPD MAF housing and airbox lid on and no limp ever again, did loose a bit power down low, put a chip in now it goes pretty good, still dialling it in a little.

I've wondered if you could just shave the inside of the standard MAF housing on a lathe and achieve similar results, I mean something like .30 tho of it, as doesn't the standard MAF housing narrow slightly in the centre of the housing to speed up the air flow past the MAF sensor, so making it straight through instead of narrowing could work? Would only be a smidge of and a cheaper option than HPD>

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Originally Posted by SG1

Done the same as above, always had some form of limp no matter what I done as in would be good for awhile but then a random limp now and then, would be good then a cold evening and then limp at 3000rpm ect or upon harder than normal acceleration and limp on gear change, ended up doing my head in, put HPD MAF housing and airbox lid on and no limp ever again, did loose a bit power down low, put a chip in now it goes pretty good, still dialling it in a little.

I've wondered if you could just shave the inside of the standard MAF housing on a lathe and achieve similar results, I mean something like .30 tho of it, as doesn't the standard MAF housing narrow slightly in the centre of the housing to speed up the air flow past the MAF sensor, so making it straight through instead of narrowing could work? Would only be a smidge of and a cheaper option than HPD>

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Id be interested in this, I also read there is an air box mod you can do yourself as well.
Maybe one of those finger files could remove some material [power file]

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Originally Posted by the evil twin

... are their Boost Controllers any good Mudski?

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I've actually got one here. Good design but the fine control is pretty shite. I was thinking of bringing in cheaper needle valves to compete with these and other cheaper needle valves being sold, as the Tognella ones I have, although they are made really well and the fine control is really good for adjusting the spool up, they are top end in price. But I can see it creating more issues than its worth. So it has been left at a thought...

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Originally Posted by SG1

Done the same as above, always had some form of limp no matter what I done as in would be good for awhile but then a random limp now and then, would be good then a cold evening and then limp at 3000rpm ect or upon harder than normal acceleration and limp on gear change, ended up doing my head in, put HPD MAF housing and airbox lid on and no limp ever again, did loose a bit power down low, put a chip in now it goes pretty good, still dialling it in a little.

I've wondered if you could just shave the inside of the standard MAF housing on a lathe and achieve similar results, I mean something like .30 tho of it, as doesn't the standard MAF housing narrow slightly in the centre of the housing to speed up the air flow past the MAF sensor, so making it straight through instead of narrowing could work? Would only be a smidge of and a cheaper option than HPD>

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First you'd have to find someone who can shave out 30thou or so in the housing. Being plastic I would be too concerned of it collapsing. Second if it didn't work, you would have lost your coin on paying someone to machine the housing out...

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Originally Posted by threedogs

Id be interested in this, I also read there is an air box mod you can do yourself as well.
Maybe one of those finger files could remove some material [power file]

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Ahh yes. I attempted it. Well sort of. I bought the necessary parts for the mod. And got the cbf's and though if I didn't do it right I'm stuffed. So I bought the HPD lid aswell as the HPD housing.

From all the discussion, it seems that the EGR blank is not really the issue. As I read it, changes to the air flow pattern causes the MAF to tell the computer to shut down for a second. That reasoning is supported by the advice to adjust the needle valve, causing different spool up rates (and consequently different air flows).
I don't see any relationship between MAF readings, and the intake manifold--UNLESS the EGR solenoid somehow opens under hard acceleration and changes air flow,
I can't find anything in my Gregory's manual, and it is fairly detailed.
Unless I find a better solution, I am going with a $???? HPDiesel housing and air box.
Comments on my "logic" (or not)

MAF sensor fitting $250, Air box lid $395 Need to quit drinking for a week!!!

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Originally Posted by mudski

First you'd have to find someone who can shave out 30thou or so in the housing. Being plastic I would be too concerned of it collapsing. Second if it didn't work, you would have lost your coin on paying someone to machine the housing out...

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Still not convinced it couldn work, a bore hone on a drill press or a round buffing/sanding of same size as MAF housing may work also, A lathe may struggle the more I think about it and possibly take a bit much of, look at the way the HPD maf housing is, it actually enlarges slightly around where the MAF sensor goes to slow down the speed of the air travelling past the MAF sensor, maybe even to much and as they state allows 30% more airflow through with out the MAF sensor sensing it, its just tricking the MAF sensor is all its doing, the standard MAF housing slightly reduces in size around where the MAF sensor goes to speed up the air flow past the maf, take away that and the air flow slows down, maf voltages are slightly lower, less limp mode. The thickness of the standards MAF housing shouldn be and issue as its not like your halving it or anything like that and no cracking of the housing should happen, maybe if you wanted it like the HPD you could let your your bore hone or round sanding/buffing do a few more rotations where the maf sensor goes and enlarher it slightly, all we are talking is a hair width.

Nearly tempted to go do and see if it could work as in theory its no different than the HPD MAF housing for $250, I think it would work with care taken and worse case if it doesn't then you were probably in the market for HPD one anyway if needed.

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Originally Posted by SG1

Still not convinced it couldn work, a bore hone on a drill press or a round buffing/sanding of same size as MAF housing may work also, A lathe may struggle the more I think about it and possibly take a bit much of, look at the way the HPD maf housing is, it actually enlarges slightly around where the MAF sensor goes to slow down the speed of the air travelling past the MAF sensor, maybe even to much and as they state allows 30% more airflow through with out the MAF sensor sensing it, its just tricking the MAF sensor is all its doing, the standard MAF housing slightly reduces in size around where the MAF sensor goes to speed up the air flow past the maf, take away that and the air flow slows down, maf voltages are slightly lower, less limp mode. The thickness of the standards MAF housing shouldn be and issue as its not like your halving it or anything like that and no cracking of the housing should happen, maybe if you wanted it like the HPD you could let your your bore hone or round sanding/buffing do a few more rotations where the maf sensor goes and enlarher it slightly, all we are talking is a hair width.

Nearly tempted to go do and see if it could work as in theory its no different than the HPD MAF housing for $250, I think it would work with care taken and worse case if it doesn't then you were probably in the market for HPD one anyway if needed.

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If you have access to these tools then yeah it may work. But most don't, including myself. Hence forking out the coin....lol. but if it could be done. Your Larfin!

I do like the Bling the factor of the HPD maf housing and airbox lid, just thinking out loud and if any one tries it don't blame me if doesn't work, I found the hardest part was undoing the standard maf housing from the standard lid as the nuts spun and broke the plastic retaining clips on mine when I changed to the HPD, was kinda spewing about that but in saying all this I am happy with the HPD products but as said just thinking out loud and may work or help someone brave enough to try.

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Originally Posted by SG1

I do like the Bling the factor of the HPD maf housing and airbox lid, just thinking out loud and if any one tries it don't blame me if doesn't work, I found the hardest part was undoing the standard maf housing from the standard lid as the nuts spun and broke the plastic retaining clips on mine when I changed to the HPD, was kinda spewing about that but in saying all this I am happy with the HPD products but as said just thinking out loud and may work or help someone brave enough to try.

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Haha. So did mine....

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Originally Posted by Dr Gary

snip...
I don't see any relationship between MAF readings, and the intake manifold--UNLESS the EGR solenoid somehow opens under hard acceleration and changes air flow,
I can't find anything in my Gregory's manual, and it is fairly detailed.
Unless I find a better solution, I am going with a $???? HPDiesel housing and air box.
Comments on my "logic" (or not)

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The MAF has two sensing elements.
1 x Air temp
1 x Air flow.
The ECU figures out the air mass (amongst other things) by the change in static and dynamic temps across the thermistors, charge air pressure, EGR position etc.

Not 100% sure what you mean by 'I don't see any relationship between MAF readings, and the intake manifold'

The EGR is fully closed under hard acceleration of (IIRC) 70% throttle or higher and won't open unless something is screwed
AFAIK the Di's are driven by a stepper, the CRDs by a closed loop control... but... there are also schematics around of ZD30's with some sort of weird arse vacuum control.
I haven't seen an Aussie one like that but I have only screwed around with a couple of early CRD's.

Hi ET and others
My comment around the MAF readings and EGR was that unless somehow the MAF triggers the EGR solenoid to open (and add exhaust pressure to the intake system, slowing down air flow) then I could not see EGR plates affecting MAF readings. From your note above, it seems the ECU looks at EGR solenoid position--not sure how that affects limp.

QUESTION FOR ALL:: Is there anyone who has "limp" cutting in, AND does NOT have an EGR plate???

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Originally Posted by Dr Gary

Hi ET and others
My comment around the MAF readings and EGR was that unless somehow the MAF triggers the EGR solenoid to open (and add exhaust pressure to the intake system, slowing down air flow) then I could not see EGR plates affecting MAF readings. From your note above, it seems the ECU looks at EGR solenoid position--not sure how that affects limp.

QUESTION FOR ALL:: Is there anyone who has "limp" cutting in, AND does NOT have an EGR plate???

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On a direct injection, I would say there is plenty.... limp mode is just an over boost safety thingo. Other factors could bring on limp mode.