supraguye Posted January 9, 2008 Share Posted January 9, 2008 Posted this in the Supra Chat area, but on second thought, i think it is much better suited for here: Hi Guys, I own a 98 vvti J-spec. I've read on here that with just a full decat, you should get 1.2 bar of boost. Right now, I would consider myself at full BPU, however I only get .7 to .8 Bar. The parts I currently have installed are: -Full De-cat with Blitz Nur Spec with no Restrictor Ring -Walbro Pump -IK24 TRD Iridium -HKS Filter -Blitz FMIC In second gear, I get up to .7 Bar and in 3rd and 4th I get between .8 and .9 Bar. I find generally the car doesn't feel strong at Low RPMs and the changeover point of the turbos is VERY apparent Can anyone help? What can I check? Thanks Quote Link to comment Share on other sites More sharing options...
styggen82 Posted January 9, 2008 Share Posted January 9, 2008 done anything to the vacuum system? boost controller or new bov? checked all ic pipes? at what rpm do you see .8 bar? mine is .8 upto 4000 then 1.2 after..... and remember the famous fuel cut at 1 bar...... Quote Link to comment Share on other sites More sharing options...
supraguye Posted January 9, 2008 Author Share Posted January 9, 2008 I have a greddy RS Bov fitted which vents to the atmosphere. I have checked the IC pipes and they all seem to be fine. I see .8 Bar between 4000 and 5000 Rpm Also, since installing the new FMIC and Bov, I have noticed that the car sometimes makes a loud popping sound from the exhaust every now n then. It appears to happen just when you are beginning to spool and you let off the throttle Quote Link to comment Share on other sites More sharing options...
foodfreak Posted January 9, 2008 Share Posted January 9, 2008 check your pipework conections for boost leaks / splits etc......you should easily hit 1.2 bar. you should hit full boost by 3800K John Quote Link to comment Share on other sites More sharing options...
supraguye Posted January 9, 2008 Author Share Posted January 9, 2008 check your pipework conections for boost leaks / splits etc......you should easily hit 1.2 bar. you should hit full boost by 3800K John Thanks mate. will pull out the guards and do a thorough check Quote Link to comment Share on other sites More sharing options...
Guest Garfy Posted January 9, 2008 Share Posted January 9, 2008 you dont say anything about an aftermarket exhaust? maybe its the restriction of the stock exhaust? just re-read, ignore me, I'm a numpty Quote Link to comment Share on other sites More sharing options...
styggen82 Posted January 9, 2008 Share Posted January 9, 2008 I have a greddy RS Bov fitted which vents to the atmosphere. I have checked the IC pipes and they all seem to be fine. I see .8 Bar between 4000 and 5000 Rpm Also, since installing the new FMIC and Bov, I have noticed that the car sometimes makes a loud popping sound from the exhaust every now n then. It appears to happen just when you are beginning to spool and you let off the throttle that popping noise is the unburnt fuel in the exhaust, this because of the bov, wich cause it to run a bit rich.. Quote Link to comment Share on other sites More sharing options...
styggen82 Posted January 9, 2008 Share Posted January 9, 2008 just a thought; is there any boost before 4000 rpm and if so how much? you should get .7 to .8 from 1800 and up... Quote Link to comment Share on other sites More sharing options...
supraguye Posted January 9, 2008 Author Share Posted January 9, 2008 just a thought; is there any boost before 4000 rpm and if so how much? you should get .7 to .8 from 1800 and up... Slightly under .5 bar .... then you feel a slight delay in the accelerationg .... and up to .8 bar. Question, do u get 1.2 Bar in all gears? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted January 9, 2008 Share Posted January 9, 2008 I had exactly this on a 98 VVTi and it turned out to be the first turbo compressor wheel was damaged and wouldn't make enough boost to start the transition to the 2nd turbo. Quote Link to comment Share on other sites More sharing options...
mattysupra Posted January 9, 2008 Share Posted January 9, 2008 simple one here, have you tried another boost gauge in case yours does not read correct? Quote Link to comment Share on other sites More sharing options...
styggen82 Posted January 9, 2008 Share Posted January 9, 2008 Slightly under .5 bar .... then you feel a slight delay in the accelerationg .... and up to .8 bar. Question, do u get 1.2 Bar in all gears? I get 1.2 in all gear as long as the wheels doesn`t start spinning:cool: just a simple question and no offence; but is both cats removed? Quote Link to comment Share on other sites More sharing options...
supraguye Posted January 9, 2008 Author Share Posted January 9, 2008 I had exactly this on a 98 VVTi and it turned out to be the first turbo compressor wheel was damaged and wouldn't make enough boost to start the transition to the 2nd turbo. Thanks chris ... will look into this Do you have any reccomendations on the easiest method of getting this checked? Quote Link to comment Share on other sites More sharing options...
supraguye Posted January 9, 2008 Author Share Posted January 9, 2008 I get 1.2 in all gear as long as the wheels doesn`t start spinning:cool: just a simple question and no offence; but is both cats removed? The cat after the turbo is dug out followed by a full 3" downpipe Quote Link to comment Share on other sites More sharing options...
supraguye Posted January 9, 2008 Author Share Posted January 9, 2008 simple one here, have you tried another boost gauge in case yours does not read correct? I haven't eliminated the fuel cut, therefore, if I were really getting as much as 1 bar boost, I would've felt when the fuel cut kicks in Quote Link to comment Share on other sites More sharing options...
supraguye Posted January 9, 2008 Author Share Posted January 9, 2008 A friend was telling me that pressure usually drops when you install a large FMIC on stock turbos. Could the problem therefore be the size of my FMIC? I have a Blitz kit installed Part # Bl 12339; it can be pictured at this link: http://www.mvpmotorsports.com/Templates/frmTemplateM7.asp?SubFolderID=214&SearchYN=N Notice that it is 4" thick, actually read somewhere that it is the largest core which can fit behind the stock bumper Quote Link to comment Share on other sites More sharing options...
styggen82 Posted January 10, 2008 Share Posted January 10, 2008 it says This 3 core intercooler is a great buy for the Supra. It comes complete with all piping, as well as the necessary overflow and power steering relocation kits to help make the install a breeze. Great for stock twins, or for those looking to go single. Approximate core size is 24" x 10.5" x 4". Quote Link to comment Share on other sites More sharing options...
supraguye Posted January 10, 2008 Author Share Posted January 10, 2008 it says This 3 core intercooler is a great buy for the Supra. It comes complete with all piping, as well as the necessary overflow and power steering relocation kits to help make the install a breeze. Great for stock twins, or for those looking to go single. Approximate core size is 24" x 10.5" x 4". Read that bit, guess i was just hoping i won't have to pull out the turbos as per chris's suggestion Got the IC piping checked and all seems well; so on Saturday, we're gonna pull out the turbos and have a look Quote Link to comment Share on other sites More sharing options...
styggen82 Posted January 10, 2008 Share Posted January 10, 2008 Read that bit, guess i was just hoping i won't have to pull out the turbos as per chris's suggestion Got the IC piping checked and all seems well; so on Saturday, we're gonna pull out the turbos and have a look good luck, keep us updatet Quote Link to comment Share on other sites More sharing options...
supraguye Posted January 10, 2008 Author Share Posted January 10, 2008 will be sure to do so. thanks for all the help Quote Link to comment Share on other sites More sharing options...
supraguye Posted January 11, 2008 Author Share Posted January 11, 2008 guys, I took the sup out for a drive tonight paying closer attention to the RPMs and boost guage Compared to you guys, who get .8 bar on the first tubbies at 1800 RPM .... I only get positive boost on them between 2500 and 3000 RPM up, with .5-.6 bar coming in closer to 4000 RPM. What can cause this sort of Lag? Then between 4000 and 4500, there is a slight moment where the car feels like the acceleration isn't as much from 4500 up, I build up to .8 -.9 bar at 5500 - 6000 RPM this .8-.9 bar seems much more violent than th .5 that I got earlier in the RPM range. I am thinking that is because both turbos are operational Quote Link to comment Share on other sites More sharing options...
styggen82 Posted January 11, 2008 Share Posted January 11, 2008 guys, I took the sup out for a drive tonight paying closer attention to the RPMs and boost guage Compared to you guys, who get .8 bar on the first tubbies at 1800 RPM .... I only get positive boost on them between 2500 and 3000 RPM up, with .5-.6 bar coming in closer to 4000 RPM. What can cause this sort of Lag? Then between 4000 and 4500, there is a slight moment where the car feels like the acceleration isn't as much from 4500 up, I build up to .8 -.9 bar at 5500 - 6000 RPM this .8-.9 bar seems much more violent than th .5 that I got earlier in the RPM range. I am thinking that is because both turbos are operational checked all the wiring and connectors to the different valves that controls the sequensial system? Quote Link to comment Share on other sites More sharing options...
Ian C Posted January 11, 2008 Share Posted January 11, 2008 Have you got a boost controller fitted? I checked the thread and you don't mention one but I thought I'd ask as I've seen one cause odd behaviour like this before. -Ian Quote Link to comment Share on other sites More sharing options...
supraguye Posted January 11, 2008 Author Share Posted January 11, 2008 Have you got a boost controller fitted? I checked the thread and you don't mention one but I thought I'd ask as I've seen one cause odd behaviour like this before. -Ian No I don't Ian Quote Link to comment Share on other sites More sharing options...
supraguye Posted January 11, 2008 Author Share Posted January 11, 2008 checked all the wiring and connectors to the different valves that controls the sequensial system? No we haven't ... Just really looking for some guidance on where to begin from you more experienced folks. Quote Link to comment Share on other sites More sharing options...
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