leon_83 Posted June 8, 2022 Share Posted June 8, 2022 Hi guys, I started having a little problem on my Supra S2 (2000 late model, 2jz-gte VVT-I, 6mt., JDM Spec.). as for the changes it has totally stock engine, it has only a full bpu with Mine's ecu. The engine has approximately 67,000 km. Suddenly he seems to be having trouble reaching maximum pressure in full boost. Normally it reached 1.2 / 1.25 bar of boost, while currently it can reach 0.98, sometimes 1.15, other times 1.08 .... Even the speed in revs seems more "sluggish" than before, but beyond that it has no grumbles, it has no progression failures ... in short, it seems "alone" with less hp Even at idle, the turbo pressure gauge, which normally fluctuates between -0.4 and -0.5, is now fixed at -0.6. In short, it seems as if there is an air leak, but about 6 months ago, all the vaccum tubes were replaced, with new clamps as well. Clean all the pipes, clean the intake system and change the filter, change the spark plugs .... etc. the car was fine, and after a few months it is showing this problem. What could I check? could it be the solenoids / VSVs? Thanks in advance guys Quote Link to comment Share on other sites More sharing options...
Style Posted June 9, 2022 Share Posted June 9, 2022 Certainly sounds like a boost leak. Even though you've refreshed all the hoses etc. there may still be a leak somewhere. Maybe a hose has been rubbing against something for a few months and a hole has appeared. So a check of the new hoses would probably be a good place to start as it's a fairly easy task to rule out. See if you can listen out for air escaping as well. Quote Link to comment Share on other sites More sharing options...
leon_83 Posted June 9, 2022 Author Share Posted June 9, 2022 39 minutes ago, Style said: Certainly sounds like a boost leak. Even though you've refreshed all the hoses etc. there may still be a leak somewhere. Maybe a hose has been rubbing against something for a few months and a hole has appeared. So a check of the new hoses would probably be a good place to start as it's a fairly easy task to rule out. See if you can listen out for air escaping as well. ok ... I will try to hear if there is any leak from any pipe or duct .... and I will double check all the vacuum pipes. Could problems with the solenoids and the Vsv be ruled out? Quote Link to comment Share on other sites More sharing options...
Scooter Posted June 9, 2022 Share Posted June 9, 2022 An old way to help rule some things in or out was to remove the sequential operation temporarily. True twin mode. I'm searching for ETTC and TTC to try and find you some relevant info. Essentially you swap a few boost pipes around and then the turbos are sequential and then if you get better boost it teels you x could be the issue, if the boost is still low y could be (it just helps you track down the problem) Quote Link to comment Share on other sites More sharing options...
Scooter Posted June 9, 2022 Share Posted June 9, 2022 This is temporary testing method. Your exhaust will sound louder on startup and the boost curve is lower (will feel lethargic at lower revs, but it might boost higher/more stable (go steady and build it up before doing a higher boost run. Try it and see/report back Quote Link to comment Share on other sites More sharing options...
Scooter Posted June 9, 2022 Share Posted June 9, 2022 In TTC it can boost higher than normal so watch out if it used to be 1.2-1.25 as above that is getting into dangerous territory! If the car runs and boosts well like this then I think the vsv's or what they operate are likely to blame. Did you replace the two link pipes between the turbos and intake? Quote Link to comment Share on other sites More sharing options...
Scooter Posted June 9, 2022 Share Posted June 9, 2022 Quote Link to comment Share on other sites More sharing options...
supraGZaerotop Posted June 9, 2022 Share Posted June 9, 2022 My issue when i had my car was the link pipes were heavy restricted due to failure, i also replaced ever vac hose and vsv, but mainly it was the link pipes last going off that was reducing the power on my car from what i can remember, car pulled super strong after fitting new ones Quote Link to comment Share on other sites More sharing options...
leon_83 Posted June 10, 2022 Author Share Posted June 10, 2022 16 hours ago, Scooter said: In TTC it can boost higher than normal so watch out if it used to be 1.2-1.25 as above that is getting into dangerous territory! If the car runs and boosts well like this then I think the vsv's or what they operate are likely to blame. Did you replace the two link pipes between the turbos and intake? what do you mean by the two link pipes between turbo and intake? are you referring to the aluminum pipes or the rubber pipes that connect the aluminum pipes? because I have also replaced the original rubber pipes with silicone one(which could swell and block the flow). In addition, the turbines received the modification to the core assy by SRD, so no more ceramic assy, to withstand even the 1.2 / 1.3 bar of boost. I had read something about the temporary modification in TTC, but from what I understand it serves to rule out any problems related to the solenoids / vsv. I had thought of proceeding in steps, first check that there are no vacuum leaks, and if all the tubes are ok, proceed to check the solenoids. I'm going crazy looking for a method. Quote Link to comment Share on other sites More sharing options...
Scooter Posted June 10, 2022 Share Posted June 10, 2022 The link pipes are what supraGZaero posted about too, but it seems those were replaced too, so won't be restricting (could still be leaking) I think TTC mod takes minutes and can help diagnose. What quality of hose was used? Do you have an after market blow off valve? Quote Link to comment Share on other sites More sharing options...
leon_83 Posted June 10, 2022 Author Share Posted June 10, 2022 3 hours ago, Scooter said: The link pipes are what supraGZaero posted about too, but it seems those were replaced too, so won't be restricting (could still be leaking) I think TTC mod takes minutes and can help diagnose. What quality of hose was used? Do you have an after market blow off valve? The hose are all BF Goodridge, with high pressure and heat resistant (with the rope texture inside them). the silicone couplers are by Whifbitz. Since i have the JDM spes i change the oem BOV with HKS ssqv one Quote Link to comment Share on other sites More sharing options...
Scooter Posted June 10, 2022 Share Posted June 10, 2022 this is another useful thread, it is going to be a (hopefully short) process of elimination.......... Quote Link to comment Share on other sites More sharing options...
leon_83 Posted June 21, 2022 Author Share Posted June 21, 2022 hi guys, Unfortunately the supposed air leak is not coming from the vacuum hoses (none are damaged, or they were inserted wrong, all clips were tight) ... Only thing that is left "old" 20 years is the HKS ssqv ( I bought the kit to regenerate the internal o-ring, and a new reinforced silicone hose ). Regarding the temporary TTC mode, I had a doubt ... that is, even if I did it, it would allow me to know if there is any solenoid / vsv not working well, but not that there could be a air leak, and, above all , where it comes from .. I'm going crazy: \ Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted June 22, 2022 Share Posted June 22, 2022 TTC mode can show if a VSV isnt working well, if it boost fine in TTC then you have an issue somewhere. I wont however show you which one.... 1 Quote Link to comment Share on other sites More sharing options...
Big Supes Posted June 22, 2022 Share Posted June 22, 2022 If you haven't already, smoke test the system. I made a DIY smoke tester years ago with a bike pump, soldering iron, a jar and baby oil and rag. 1 Quote Link to comment Share on other sites More sharing options...
leon_83 Posted June 24, 2022 Author Share Posted June 24, 2022 ok, i will try a smoke test from my mechanic ... hoping it can help solve the mystery I noticed, however, one thing .... disconnecting my HKS ssqv bov, and blowing inside the tube connected to it, the air does not remain sealed but vent a little ... (I blew with my mouth not with the compressor) , is this vent normal? or in any case at low pressures should they be completely sealed? Quote Link to comment Share on other sites More sharing options...
TuneR Posted June 24, 2022 Share Posted June 24, 2022 Have you tried refitting the stock valve? There was an issue with the VVTi engine and BOVs, i just cant think of what it is. Quote Link to comment Share on other sites More sharing options...
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