SJMKIV Posted May 10, 2012 Share Posted May 10, 2012 Hey guys, I finally went BPU and just went for a test run to see if the car was building boost as it should. Was hoping to hit fuel cut at 1bar, as my Boost Cut Controller is to be installed tomorrow, but the car isn't boosting to more than 0.95bar at WOT in 2nd gear. Hitting max of 0.6bar on the first turbo. To give you an idea of what I'm driving - '95 J-spec TT on stock twins - 2.5" 1st Decat - 3" 2nd Decat - 1.2bar RR - RSR 3" Cat back - Greddy 3Row FMIC - Walbro fuel pump - Koyo Radiator - Apexi intake - Denso IK24 Spark Plugs - Turbosmart Supersonic BOV - MVP Boost Cut Controller (not yet installed) Do you think the issue could be the 2.5" 1st Decat causing too much restriction? I do have a Blitz SBC ID boost controller - is is advisable for me to increase boost with this based on the setup I have? Maybe I could get rid of the Restrictor Ring has the Decat is restricting anyway? Not sure if I'm thinking on the right track.. any help would be highly appreciated! Thanks a ton!! SJ Quote Link to comment Share on other sites More sharing options...
Peter P Posted May 10, 2012 Share Posted May 10, 2012 I'd personally get the FCD (think this is what you mean by boost cut controller?) setup before trying anything else. Other thing to check is all your vac pipes are on properly, and aren't split or leaking. It's a bit of a chore going through them all, but not nicknamed the rats nest for nothing! Lol. You can remove the restrictor ring and see if that helps, but keep a close eye on the boost to make sure it doesn't go the other way and overboost! Have you checked your turbo's for excess play etc? What mileage have they done?? Quote Link to comment Share on other sites More sharing options...
themodifiedkid Posted May 10, 2012 Share Posted May 10, 2012 As peter has said, but be really thorough when checking for leaks. It happened to me, so i pressurised the system and was shocked to find 2 or 3 leaks mainly from the intercooler piping Quote Link to comment Share on other sites More sharing options...
SJMKIV Posted May 11, 2012 Author Share Posted May 11, 2012 I'd personally get the FCD (think this is what you mean by boost cut controller?) setup before trying anything else. Other thing to check is all your vac pipes are on properly, and aren't split or leaking. It's a bit of a chore going through them all, but not nicknamed the rats nest for nothing! Lol. You can remove the restrictor ring and see if that helps, but keep a close eye on the boost to make sure it doesn't go the other way and overboost! Have you checked your turbo's for excess play etc? What mileage have they done?? Yes, I meant FCD. My car has about 55,000miles on it. Maybe I should get rid of the RR, install the FCD, check the entire system for leaks and then see how it works out. But you guys don't think it could be the 1st Decat causing too much restriction? SJ Quote Link to comment Share on other sites More sharing options...
SJMKIV Posted May 11, 2012 Author Share Posted May 11, 2012 also, would it be ok for me to increase boost using my boost controller? Quote Link to comment Share on other sites More sharing options...
listy Posted May 11, 2012 Share Posted May 11, 2012 I wouldnt have though the decat is making much difference mate. Its wider than the RR anyway, but Im not an expert on these things yet. What is your boost controller set to? And I think JSpecs require the RR regardless of a boost controller being fitted or not iirc. I would be worried about overboost if its not there. Quote Link to comment Share on other sites More sharing options...
SJMKIV Posted May 11, 2012 Author Share Posted May 11, 2012 I wouldnt have though the decat is making much difference mate. Its wider than the RR anyway, but Im not an expert on these things yet. What is your boost controller set to? And I think JSpecs require the RR regardless of a boost controller being fitted or not iirc. I would be worried about overboost if its not there. My boost controller is currently off. the RR is the same diameter as the 1st Decat i.e 2.5" (therefore is pointless). Quote Link to comment Share on other sites More sharing options...
Peter P Posted May 11, 2012 Share Posted May 11, 2012 As I said, get the FCD fitted and setup first. Then try removing the restrictor ring, and try setting boost to 1.2bar being the generally recognised safe limit for J spec turbo's. I'm not convinced that the restrictor ring is causing a problem though. If it's the same diameter as your 1st decat, then it shouldn't make a difference. Most 1st decat pipes are 2.5' diameter, and they don't have issues when fitted along with a restrictor ring. My money is still on a boost leak somewhere. Vac pipes and intercooler hoses are a good place to start. You can try revving it from the engine bay to see if you can hear any air leaks? Keep us posted fella, and hope you get it sorted. Peter Quote Link to comment Share on other sites More sharing options...
Nic Posted May 11, 2012 Share Posted May 11, 2012 It'll either be that the hole in the restrictor ring is too small ie. causing too much of a restriction or one of the vacuum/IC hoses is leaking. Fit an FCD, adjust the size of the restrictor ring hole so it'll boost to 1bar, then use the boost controller to raise the boost pressure to 1.2bar Quote Link to comment Share on other sites More sharing options...
TubbyTwo Posted May 11, 2012 Share Posted May 11, 2012 Replace all the turbo related vacuum hoses, did this on mine after splitting one last weekend and it runs so much better. Not a huge job. Quote Link to comment Share on other sites More sharing options...
SJMKIV Posted May 11, 2012 Author Share Posted May 11, 2012 Just for the record, all the hoses in my engine bay have been replaced about 5-6months back with silcone ones. Around the same time I had fitted the Greddy FMIC with all hard pipes. Nic, my RR is the same diameter as the 1st decat, i.e 2.5". Therefore I assume its serving no purpose as all the restriction is being caused probably by the 1st Decat; unless there is a boost leak like many of you think it to be. Would it be safe for me to raise boost using the boost controller if I'm currently boosting close to 1bar? or will that cause too much heat build up? SJ Quote Link to comment Share on other sites More sharing options...
Nic Posted May 11, 2012 Share Posted May 11, 2012 Nic, my RR is the same diameter as the 1st decat, i.e 2.5". Therefore I assume its serving no purpose as all the restriction is being caused probably by the 1st Decat; unless there is a boost leak like many of you think it to be. The hole in the middle of the restrictor ring is 2.5"? The 2.5" decat pipe will not be the cause of the restriction. If the restrictor ring does have a 2.5" hole in it then I'd suspect a leak on one of the hoses. Would it be safe for me to raise boost using the boost controller if I'm currently boosting close to 1bar? or will that cause too much heat build up? Yes it'll be fine. Do you have an exhaust gas temp gauge fitted? Quote Link to comment Share on other sites More sharing options...
listy Posted May 11, 2012 Share Posted May 11, 2012 Not meaning to sound like an idiot here, but I'm sure my RR is less in diameter than 2.5" (maybe 2"), and mine boosts at around 1.1 bar. I vote boost leak on one of the vac pipes or one of the IC pipes. IC pipes are quite a common place for a leak. Quote Link to comment Share on other sites More sharing options...
SJMKIV Posted May 11, 2012 Author Share Posted May 11, 2012 Just got back from a drive.. tried increasing boost using the boost controller, but yet max boost I got was 0.97bar. Normally boosting to 0.91-0.94bar. as most of you say, it seems to be a boost leak and possibly my boost controller isn't installed properly as it made no difference whatsoever when I increased boost. Now, onto a hunt for threads on 'how to find boost leaks'! If you guys have any more inputs, please please do share! thank you for the help guys, much appreciated. SJ Quote Link to comment Share on other sites More sharing options...
Samurai 20V Posted May 12, 2012 Share Posted May 12, 2012 Did you adjust the offset/gain on the boost controller? Quote Link to comment Share on other sites More sharing options...
SJMKIV Posted May 12, 2012 Author Share Posted May 12, 2012 Did you adjust the offset/gain on the boost controller? Yes I did. Offset to 20 and Gain to 15. Quote Link to comment Share on other sites More sharing options...
SJMKIV Posted May 12, 2012 Author Share Posted May 12, 2012 Yes it'll be fine. Do you have an exhaust gas temp gauge fitted? Nope, no EGT Quote Link to comment Share on other sites More sharing options...
Guest Budz86 Posted May 12, 2012 Share Posted May 12, 2012 Just out of interest, what gear are you getting the boost readings from? I may be teaching you to suck eggs but BPUs build more boost in higher gears - generally I'm in at least 3rd on a cold day or 4th on a warm day before I hit Max boost. In 2nd it doesn't seem to hit more than 0.9 bar Quote Link to comment Share on other sites More sharing options...
jay200bhp Posted May 12, 2012 Share Posted May 12, 2012 do you hear a hissing in the cabin as the hard pipe from the back of the unit can leak if the joint to the vac system isnt a good seal Quote Link to comment Share on other sites More sharing options...
SJMKIV Posted May 12, 2012 Author Share Posted May 12, 2012 Just out of interest, what gear are you getting the boost readings from? I may be teaching you to suck eggs but BPUs build more boost in higher gears - generally I'm in at least 3rd on a cold day or 4th on a warm day before I hit Max boost. In 2nd it doesn't seem to hit more than 0.9 bar hitting 0.92-0.95 right from 2nd to 4th.. temperature where I am is around 30'c. Quote Link to comment Share on other sites More sharing options...
SJMKIV Posted May 12, 2012 Author Share Posted May 12, 2012 do you hear a hissing in the cabin as the hard pipe from the back of the unit can leak if the joint to the vac system isnt a good seal Haven't heard any hissing.. Quote Link to comment Share on other sites More sharing options...
SJMKIV Posted May 14, 2012 Author Share Posted May 14, 2012 hey guys.. just an update found a crack in my RSR Cat Back exhaust. thought I'd try it out with only the decats in place and without the catback. extremely loud, but again didn't boost over 0.9ish bar. Guessing the next step is to check for boost leaks. Is there anything else that could be the issue? from what I've understood from many of your posts is that the 2.5" 1st decat cannot cause so much restriction as to keep it at 0.95bar SJ Quote Link to comment Share on other sites More sharing options...
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