Turbo spooling up far to quickly

[davrol]

Need a little help with something.

After having NADS on for 6 months or so, I noticed the turbo was struggling to hit the 15 i had set originally. After doing a lot of reading about possible causes, i worked out that it was likely the dawes valve, so i pulled it apart, stretched spring a little an re-assembled.

First run, i closed needle valve to make sure i was at right boost being 15psi and it hit it no worries at 2000rpm. Now i wind the needle out and i am getting the 5psi @ 1500 &10psi @ 2000 recommendations in 4th but once it gets to 10, it is rocketing to 15 at 2500 rpms. Now don't get me wrong it goes great but i have also read that a safe level would be 3000 for 15 because it will go into limp but it is not limping. Now i haven't been flogging it around the place as it is boosting high but i am just not sure why it is not limping. It does have a steinbauer chip in it but i am not sure that will have anything to do with it.

Could it be anything to do with the dawes? I didn't think so as it is hitting full boost and staying there. I am not a huge fan of this needle valve, not hat i have ever purchased one before, but it seems cheap.There is a lot of turns from open to closed, probably 25 to 30 and when you close the valve, although when it is closed it doesn't let any air through it just doesn't screw all the way in and look closed. I am not sure that has anything to do with it. I purchased it from DD. It is a black valve with a silver sticker with blue writing and a very small adjustment knob.

My new IC comes next week so i know i will be up for some fine tuning then but is there something i have overlooked here?

Thanks in Advance.

Cheers

Dave

[Rumcajs]

Hi there,

15 psi max boost is safe limit even at 2000 RPM under fair load.

Limps usually occur if your boost hits 18 psi under 3000 RPM so staying within 17 psi envelope will keep limps away.

Also Dawes valve weaker spring will have tendency to do boost bounce so your peak boost will temporarily raise higher.

I recommend to contact 3Barrracing and obtaining the stronger spring they're now selling for Patrols. That one will reduce the bounce but thread carefully as it brings higher boost more rapidly so be careful with the setting it up.

 

Cheers

[davrol]

Rumcajs,

 

Thanks a lot for the info. I will leave it as for now and re-tune when I install CC IC.

 

Here I am driving around with it struggling to hit 15 psi and thinking this is great. Idiot. Now it goes really well. Off the throttle much sooner and EGT's down substantially.

 

I will let you know how it is going after IC install.

 

Thanks again.

[davrol]

Hello again,

 

Still waiting on my IC to come. They have a new story every week after telling me the week before it is on its way. Anyway.

 

Got a newer HD spring for the dawes valve. It was not the one from 3 Barr. Was actually a spring out of a gas valve exactly same diameter as the one in it and thicker coils. It was a little long but I trimmed it down and it works a treat. Or at least I think it does....

 

I am pretty sure I have now experienced limp mode. I pretty much have it set up exactly the same as before I changed the spring but now when I keep it under moderate to high load for 5 seconds or so it looses power.I take foot off & re-apply & it is fine. I have wound the dawes down to 12-13 but it still does it. Surely my gauge could not be 5psi out.

 

I have done a little research and found similar symptoms with faulty TPS or change fuel filter/air filter. Fuel filter is 15000kms old so maybe, but I generally only get fuel from the same Caltex and 15000kms isn't that old for a fuel filter is it? Air filter is the same kms. I will blow air filter out tomorrow to rule it out.

 

I just think it is too convenient that I have changed the spring and now this is happening. Before you ask I lost the original damn spring. I swore I put it in my cup holders but it is not there. Grrrrrr!!!! I can buy the 3 barr spring but if it is not boosting above 13 I am not sure how it could go into limp in relation to boost at these levels ( on what I have learnt so far).

 

I am driving up to QLD next week and doing a day trip to Fraser and I want to try and have this sorted before then.

 

Is there anyone on here in Sydney that has ECU talk or a cable and software ( and a fridge to put some beer in ) that may be able to give us a hand?

 

Any help appreciated.

 

Cheers

Dave

Edited April 10, 2014 by davrol

[Rumcajs]

That seems familiar and is well known problem, normally reason for limps is also MAF voltage, usually anything over 3.99V under 3,000RPM will cause the fuel cut (limp) and usually in 3rd or 4th gear.

Many of us with Dawes and needle valve boost control are battling this phenomenon either restricting the air flow capability (slower spool up) or using artificial means to alter to MAF signal either clipping it to stay under 3.95 or manipulating it entirely with voltage modifier.

 

Some are slowing the spool up and max rate by reducing the maximum opening of turbo vanes (there is a stop screw in there) or quite a few are now using JDVM (Jaycar Digital Voltage Modifier) unit which works like a charm but is complex to assemble from scratch and also not that easy to configure (trial and error time consuming to find out the best setting). The results are however worth the effort.

 

Cheers

[davrol]

Rumcajs

 

Went to Jaycar to get Voltage modifier but they tell me they no longer sell it. It says available on the website, so I think I might just order online.

 

You don't happen to know the dimensions of the HD spring for dawes do you? Length and width.

 

Cheers

Dave

[Rumcajs]

Well I have a couple of spares (Dawes valve HD springs) but that's not much of a use (knowing it physical dimensions).

Anyway description on the packet says 0.36x0.032x0.875 (I'm assuming in inches) Prec. comp. Spring there is also name Gardner Spring with part number 1-800-331-3263 and 36061Ci.

 

Don't forget you also need Jaycar hand controller with the JDVM.

 

Cheers

[davrol]

Thanks. Trying to find a HD spring for a dawes locally as I think I have left it too late to get from US before I travel to QLD.

 

You don't want to part with one of your spares do you? I will pay for it of course.

 

Cheers

[Rumcajs]

I suppose I could part with one but how do you propose we do such exchange, it will be only a couple of bucks....

 

Cheers

[davrol]

Thanks heaps!

 

I could just transfer money for spring ( and the costs of freight you paid for it) & an express post satchel into your bank account. If I transfer Monday it should go into your account Tuesday. That is if you have time to put it in express post for me.

 

Let me know your thoughts. Thanks again!

 

Cheers

Dave

[Rumcajs]

OK per spring it costed ~ $2, you can have it for free as it is just a hassle to transfer such small amount.

I'll PM you my address so all you need to do is send me a self addressed paid return postage envelope,  the size of the spring is tiny....

 

Cheers

 

Edit: PM sent,

Edited April 12, 2014 by Rumcajs

[davrol]

Worked out why my truck was hitting limp.  All weekend I have been trying different springs from here and there and they were only getting to 7-10 psi on my gauge. After the 4th spring doing the same thing I started to wonder why. Blew 15 psi up line to boost gauge and only getting to 5 psi. Hmmm. I did not believe it at first. Got under the bonnet with my mate who was blowing air to gauge and I heard this hissing noise from the filter. Bingo!  Inline filter to gauge was cracked. It was over boosting and that is why it went into limp mode. After fixing the gauge it was hitting 25psi. Oops! Adjusted and back to hitting 15 at 2500 and boost peaks at 17. No limp with foot flat to the floor right through rev range. Man it goes good.

[Wags83]

Good pickup Davrol. I'm struggling to get anywhere over 12 Psi at this stage. Hitting limp mode at around 3000rpm at around 10Psi. Got a new MAF sensor, and a full service on the weekend. Got me stumped, any ideas would be much appreciated.

 

2000 GU patrol, NADS, rebuilt 3L (30000kms), snorkel etc. etc.

[Rumcajs]

Good pickup Davrol. I'm struggling to get anywhere over 12 Psi at this stage. Hitting limp mode at around 3000rpm at around 10Psi. Got a new MAF sensor, and a full service on the weekend. Got me stumped, any ideas would be much appreciated.

 

2000 GU patrol, NADS, rebuilt 3L (30000kms), snorkel etc. etc.

 

 

You need to check what the ECU is seeing as if your external gauge is showing 10 psi and you are getting limp that means that either the boost is past 18 psi or your MAF voltage is past 3.99 V bellow 3000 RPM. Boost and MAF signals are directly related.

 

ECU Talk software with cable will make this easy, other way is with multimeter.

 

Cheers

Edited May 7, 2014 by Rumcajs

[davrol]

Have you tested your boost gauge to make sure it is working correctly? That was what the issue was with mine.

 

Cheers

[Wags83]

Thanks gents I'll check the voltage on the plug to the maf. I'll check the other threads for info on how to do that. I've got another gauge to test against my boost gauge and check my piping to it aswell. Has anyone had the flash code 0406 come up? I'm thinking it's an egr issue, does the zd30 have an egr valve that can become sticky?

Cheers

[Rumcajs]

Indeed ZD30 does have EGR valve issues from time to time but most of us fix that with teh shim. ECU uses/applies EGR and VNT control together under certain circumstances.

Cheers

[Wags83]

I'll check that out too, thanks again rumjcas