Flip Posted June 30, 2007 Share Posted June 30, 2007 Hi, I've been searching and can't find a definative answer for this, so here goes:- I have a full decat, and a AEM Truboost controller on stock j-spec tubbies. Now, I know max boost on number two is 1.2bar - but even with my wastegate crack pressure set nice and low, (about .1bar!) I get a max boost of around 1.28bar, but watching the boost gauge it seems to be sustaining around 1.1 - 1.15bar - obviously with a spike of over 1.2 somewhere, but the main bulk of the actual boosting is under 1.2 bar.... now, is that safe? Can I up the boost so the sustained level is nearer 1.2 bar, and I ignore the max boost as it most only happen for an instant?? Link to comment Share on other sites More sharing options...
RobEvans Posted July 1, 2007 Share Posted July 1, 2007 I suffer from this to... Link to comment Share on other sites More sharing options...
Flip Posted July 1, 2007 Author Share Posted July 1, 2007 I thought it might be the wastegate pressure setting, but I basically have it at zero now and it still does it! Link to comment Share on other sites More sharing options...
RobEvans Posted July 2, 2007 Share Posted July 2, 2007 No Idea Iv been trying to find out for ages... Bump Link to comment Share on other sites More sharing options...
Flip Posted July 3, 2007 Author Share Posted July 3, 2007 It would be useful to know if it does any damage at least - ideally I want "fix" it as boost spikes are bad! Don't want my tubbies to explode on me! Link to comment Share on other sites More sharing options...
mike_mcevoy Posted July 3, 2007 Share Posted July 3, 2007 As you have the full decat do you have the correct sized restrictor ring in place otherwise it will just over boost on the j-spec. Someone will be able to give a more technical answer, but that's the core of it. Michael Link to comment Share on other sites More sharing options...
Flip Posted July 3, 2007 Author Share Posted July 3, 2007 Yep, got the RR in, without the boost controller on it spikes around 1.1 and sustains about 1bar boost. Link to comment Share on other sites More sharing options...
Sheefa Posted July 3, 2007 Share Posted July 3, 2007 Mine peaked to 1.35 yesterday and it's NEVER done that before! It was a bit of cold weather no doubt, but settings on my BC should limit it to 1.25 (I'm running stronger hybrids though). God knows what my duty cycle was on the J-spec fuelling. I quickly toned the boost settings and am now back to running a healthy 1.2bar, sometimes peaks at 1.23. Have you fiddled much with the set and gain configs? Link to comment Share on other sites More sharing options...
Flip Posted July 3, 2007 Author Share Posted July 3, 2007 The AEM has wastegate open pressure and gain, and yes, I've played with them, but no matter what I set I can't seem to get the peak boost nearer the sustained boost - if you see what I mean. I've just had a thought, what would happen if the line from turbo to boost controller solenoid and back to wastegate was a total of about 50cm long, could that cause this problem? Link to comment Share on other sites More sharing options...
Flip Posted July 4, 2007 Author Share Posted July 4, 2007 *bump* Link to comment Share on other sites More sharing options...
supra100 Posted July 4, 2007 Share Posted July 4, 2007 Apologies for hijacking this thread but I'm about to install a tru boost today. Installing the gauge appears simple enough but being a novice here do you possibly have any photos or can indicate exactly where I connect to the solenoid to. Which pipes etc. Do I simply T piece in etc. I've looked at various threads but non appear clear enough. Many thanks in advance:) Link to comment Share on other sites More sharing options...
Mike B Posted July 4, 2007 Share Posted July 4, 2007 Maybe you need a smaller restrictor ring, or the ring is damaged. we had the get the wastegate enlarged on our r34 as it creeps when pushed over 1 bar. My old Jspec has this creep too, it had single decat and no RR. Link to comment Share on other sites More sharing options...
dangerous brain Posted July 4, 2007 Share Posted July 4, 2007 Boost spiking to 1.2 bar with a 1.2 bar RR isn't much of a surprise really. You know somethings wrong when it starts whanging around to 1.6 like mine did with an incorrectly fitted DSBC. Boost controllers can only up the boost not drop it and the fully decatted J-spec on stock tubbies and stock wastegate with a 1.2 bar RR will go to 1.2 bar. It may swing past that a bit if your gain is set to quicker. It won't however be very easy to set it below 1.2 bar. If you want lower boost fit the 1.0 bar RR and then tweak it up from there with a boost controller. Link to comment Share on other sites More sharing options...
Ian C Posted July 4, 2007 Share Posted July 4, 2007 I wouldn't worry about a spike to 1.28bar. It'll be quite brief at the point the second turbo comes online. -Ian Link to comment Share on other sites More sharing options...
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