Boost/power troubles after EGR and/or new intercooler

[Hodge]

Just posting this up to see i anybody had similar problems and/or any ides what this could be ... I mentioned some of it in my diesel power intercooler write up last week so some may be familiar with my problem.
Firstly thanks a heap to Mudski for helping us out with trying different mafs and egr plates... Was over at his place for a bit last night talking s*** and throwing out ideas.

Flow of events...
Fitted up dawes and needle valve ages ago and the car ran like a million bucks after it. Then I dropped in a EGR plate. Had to wind down needle a tad, since it was spooling up a bit faster with EGR blanked. So had the car running flawlessly for about a month like this.

Then last week I installed a new diesel power re-cored and tig welded intercooler and at the same fitted up a catch can. The car ran fine for half a day or a day and then it turned to s*** ...

Basically what's happening is, it'll fly through 1st , 2nd and 3rd gear boost spooling up fine or quicker than usual and maxing out boost. Then in 4th the car begins to labour, and spooling up takes a little longer than usual. Basically, it's turbo lag. It does get there, but very slow. EGT goes sky high until boost picks up. The other thing is @ 100km/h where my cruising boost was around 10-11, now hits 17 (my max) as soon as i touch the throttle.

So the trouble is, if I wind down needle to fix 1st 2nd and 3rd, I'll make 4th much worse... If I wind it up, to fix 4th, the first 3 gears are terrible as it shoots to max boost in a second and the snail is spinning it's tits off for no gain...

The other little variable is... Up until I've installed the intercooler, I've had NO codes on the system. As soon as the IC was fitted, P0401 ( no EGR flow) code popped up. Which is common on the common rails after blanking the EGR. I'm just getting the code on scan gauge and no engine light.

Could this larger intercooler be messing with my head and just making the mid range gears and power more unstable ? Maybe the extra flow of air into the system, is somehow stuffing up the EGR valve? Also does this P0401 code do anything to the system like put car into limp mode or somethign, or is it just a warning.

I've began the process of elimination, took EGR plate off and re-fitted old gasket to see what happens to begin with. This will drop spool up rates across the board a little.

Any ides would be appreciated. The car as it is now is, not pleasant to drive. Very frustrating as I need the rig over the next few weeks to run well!

[the evil twin]

P0401 should illuminate the engine light and latch it until cleared.
If you have the code on the Scangauge and no engine light it is either an artifact on the Scangauge and the code isn't new OR something is dodgy with the ECU not latching teh check engine light.

You obviously have a problem if the EGT's are skyrocketing and it may be simply the Dawes/Needle settings but I can't help you there.
After blocking EGR I left my Turbo as ECU controlled and adjusted the VNT as per the bible and she goes gangbusters.

[boots]

The scangauge eliminates or over rides faults if you need doesn't it Hodge . ? Mate I would try a new spring in the dawes valve , reading your post suggests you've tinkered with it a fair bit so it or even the ball seat may be suspect . 17PSI max with a fresh IC may be a poofteenth too high also , some like it some don't . Hope you sort this out mate .

[Hodge]

Thanks for the posts guys!

@the evil twin
The code 100% wasn't there before intercooler/catch can install, and 110% didn't show up an engine light. Code clears with scangauge. After blocked the EGR again last night and code is gone and not returning.

@boots
I didn't touch the dawes valve much, if at all, because my max boost never changed or didn't need to, so it may not be the spring maybe. I'll try lower boost like you suggested.

Was talking to Mudski again, and I'll re-setup the valves a slightly different way to see if it helps anyway. If not I'll have to start looking at other things. Another thing I noticed it runs ok-ish when cool, like morning and within 10-15 minutes it starts to go a tad sluggish so... Anything is possible right now.
One of the things I'm worried about is the day before it began doing this, I was due for a tank fill and the main tank was below quarter so, it may have maybe picked up crap of the bottom of tank. So fuel filter is next on the check list if boost system doesn't help. Either way it's not running too smoothly at the moment so, watch this space.

[Hodge]

Just re-designed the dawes/needle setup, and I'm not 100% but it may have improved a little. Will test out tomorrow. Fingers crossed.

[Hodge]

Just thought I'd update this.
After re-shuffling some of the boost control vacuum hoses and re-doing the dawes/needle setup the car now hammers again.
Thanks to mudski for pointing this out.

[threedogs]

over a period of a few months I fiddled with the dawes
and needle until I found a happy spot goes like its stolen now lol

[Hodge]

over a period of a few months I fiddled with the dawes
and needle until I found a happy spot goes like its stolen now lol

Well I had that sweet spot until I slotted in the new IC. The car went so good, I didn't want to touch anything else in case I lose it. And lose it I did, with the new IC... But now it's all about tuning it to that sweet spot again. I also re-newed some factory hoses which I reused in the setup. So it may also have been some of those hoses leaking or blocked.

[threedogs]

can you put up some EGT readings later for 100kph , 60kph etc If possible
Would like to compare to to an OE tigged unit

[boots]

So is the egr blocked or not Hodge