Scott Posted May 14, 2009 Share Posted May 14, 2009 Recently had the tubby's replaced on my supra but i'm not seeing the boost figures i would expect for BPU. I have the following.. FMIC Double De-Cat RSR II Exhaust 1.2bar Restrictor ring When the first turbo comes online i'm seeing approx 0.5-0.6 bar (expected around 0.8), when the 2nd turbo comes on i'm seeing approx 1bar max (expecting 1.1-1.2ish). It also comes on a bit late, i'm seeing full boost around 5000rpm. So far i have ran it in TTC mode and the pressure tank is holding just fine, still only getting 1bar and the power still comes in later than it should. Any ideas what i should look at? Could it be a leaky BOV or a leak in the intercooler piping? It is suggesting to me that its a very small leak as there is only a slight drop in pressure. However, i'm not sure how to diagnose the boost coming in later than it should. Quote Link to comment Share on other sites More sharing options...
Scott Posted May 14, 2009 Author Share Posted May 14, 2009 Just thinking out loud but would this theory be correct? If there was a small boost leak, say from the dump valve, would that mean that only having 0.5bar wouldn't be enough to activate the EGCV therefore slowing the spool of tubby 2 giving the late boost? Also once the 2nd turbo kicks in the small leak is still there only allowing 0.9bar? Quote Link to comment Share on other sites More sharing options...
Scott Posted May 14, 2009 Author Share Posted May 14, 2009 Dp Quote Link to comment Share on other sites More sharing options...
Scott Posted May 14, 2009 Author Share Posted May 14, 2009 Evening bump, can noone help me? I've tightened up the connections on the dump valve and it made no difference. I ran TTC mode again and it comes in hard just after 4k rpm. I expected full boost around 3.5-3.8k rpm. My next test is taking the dump valve out completely but that will have to wait as i'm off to japfest tomorrow. Quote Link to comment Share on other sites More sharing options...
Kirk Posted May 14, 2009 Share Posted May 14, 2009 I dont know how much help i can be to you mate but ill try. sounds to me like a boost leak somewhere, eiter from BOV or intercooler piping, possibly vacuum lines with a pin hole? but if the pressure tank is holding i cant realy see it being. is it a stock bov? Quote Link to comment Share on other sites More sharing options...
Scott Posted May 14, 2009 Author Share Posted May 14, 2009 I dont know how much help i can be to you mate but ill try. sounds to me like a boost leak somewhere, eiter from BOV or intercooler piping, possibly vacuum lines with a pin hole? but if the pressure tank is holding i cant realy see it being. is it a stock bov? Thanks for the reply No buddy, its an HKS valve i have. I still need to rule it out though so it will be coming out at one point. One of the vac lines did have a pin hole in it but i replaced that. I'm not really sure if this makes any difference but i tried to get the EGBV to open using an air compressor. It took almost 20 psi before the thing opened. Eventually when it opened all the way it popped off one of the hoses. Does the EGBV get opened with the combined pressure from the pressure tank AND the manifold or something? I notice there are 2 lines going into it. At least that would explain why it took so much pressure to open it. Quote Link to comment Share on other sites More sharing options...
Kirk Posted May 14, 2009 Share Posted May 14, 2009 that doesnt sound right to me! it shouldnt take that much pressure to open surely not? id try removing the BOV and rule it out 1st then the intercooler pipes, then guess all thats left is to check all the lines to the turbos etc I dont supose maybe the spring in your BOV is knackered and is opening under light load?? Quote Link to comment Share on other sites More sharing options...
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