Guest lewk Posted December 3, 2013 Share Posted December 3, 2013 Hi guys. I own a twin turbo auto supra that has most the bpu upgrades apart from hks fcd (which I've been told not to fit) and a boost controller. The rest is all fitted. I've recently noticed that when the car reaches high rpm and goes to change gear there's a big jolt and almost it seems a loss of power at the same time... Before bursting back into life again. I would call it a flatspot but it seems asif there is no power at this point and not just limited. I've got an updated fuel pump on it and it has a 1 bar boost restrictor so I would imagine it's not the fuel system as I'm not putting out crazy amounts of boost and probably only running around 400bhp ish. Has anyone else experienced this? And does it sound like a gearbox problem? My gearbox also clunks into drive and reverse very harshly when cold. Many thanks Lewis. Quote Link to comment Share on other sites More sharing options...
Dnk Posted December 3, 2013 Share Posted December 3, 2013 (edited) Could be overboosting and hitting fuel cut in the colder denser air I guess its an auto, has the atf ever been changed along with a new filter, check the level and colour on the dipstick, it should be cherry red. Edited December 3, 2013 by Dnk (see edit history) Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted December 3, 2013 Share Posted December 3, 2013 Id also say boost cut, thats what the FCD eliminates. Quote Link to comment Share on other sites More sharing options...
Abz Posted December 3, 2013 Share Posted December 3, 2013 Id also say boost cut, thats what the FCD eliminates. I'd go with this too. Quote Link to comment Share on other sites More sharing options...
Alex Posted December 3, 2013 Share Posted December 3, 2013 To be pedantic. It's not boost cut, "it's fuel cut triggered by overboosting". Quote Link to comment Share on other sites More sharing options...
Dnk Posted December 3, 2013 Share Posted December 3, 2013 To be pedantic. It's not boost cut, "it's fuel cut triggered by overboosting". Quote Link to comment Share on other sites More sharing options...
Fitz Posted December 3, 2013 Share Posted December 3, 2013 when you say High RPM is that in every gear? Or around 112mph? (Just checking the simple things first) Quote Link to comment Share on other sites More sharing options...
st3ven1 Posted December 3, 2013 Share Posted December 3, 2013 It's fuel cut. OP goes BPU but doesn't fit FCD(fuel cut defender) and wonders why he is getting fuel cut! If it looks like a duck and all that. OP, try to seek out a TRL VFCC and this will solve your problem. Might be worth putting up a wanted thread as they are no longer made. Quote Link to comment Share on other sites More sharing options...
Guest lewk Posted December 3, 2013 Share Posted December 3, 2013 It tends to happen in higher gears at faster speeds... I have the hks fcd already but not fitted as I've spoke to a number of specialists as I wasn't sure what it was for and they have all said don't fit it because they know of a number of cars that have it and run lean at higher rpm, then things go pop! A lot of rolling roads also told me they won't touch it if it has one on. It there another route around this? - - - Updated - - - Run lean with the hks fcd that is... Quote Link to comment Share on other sites More sharing options...
supra_ufo Posted December 3, 2013 Share Posted December 3, 2013 It tends to happen in higher gears at faster speeds... I have the hks fcd already but not fitted as I've spoke to a number of specialists as I wasn't sure what it was for and they have all said don't fit it because they know of a number of cars that have it and run lean at higher rpm, then things go pop! A lot of rolling roads also told me they won't touch it if it has one on. It there another route around this? - - - Updated - - - Run lean with the hks fcd that is... Click on the blue FCD hyper link mate, explains why a BPU supra needs it. Then dump your specialist and go to someone like Whiftbitz (local to you) Quote Link to comment Share on other sites More sharing options...
Guest lewk Posted December 3, 2013 Share Posted December 3, 2013 Haha cheers bud! I'm not against using it I just don't know what to do as I've heard lots of different things haha hence the post on here. Thanks for your help Quote Link to comment Share on other sites More sharing options...
Guest lewk Posted December 3, 2013 Share Posted December 3, 2013 It does say this on the hyperlink though.. Cons: Crap FCDs scale the airflow input so that when the stock sensor hits 1.25bar (it's maximum) the ECU gets a shade under 1.0bar. This also has the effect of scaling the ENTIRE airflow signal so the ECU always receives a lower airflow value than the engine is really getting. Messes up the whole fuelling map towards the lean end of the spectrum and is therefore highly not recommended. Does everyone here have a fcd fitted? Quote Link to comment Share on other sites More sharing options...
supra_ufo Posted December 3, 2013 Share Posted December 3, 2013 Haha cheers bud! I'm not against using it I just don't know what to do as I've heard lots of different things haha hence the post on here. Thanks for your help I think the easiest way to explain, it tricks your ECU (car brain) to thinking its ok to boost past the stock pressure of 0.76 therefore it does not trigger the Fuel Cut (The car brains failsafe to protect the car from overboosting, in this case its ok for it to overboost). Quote Link to comment Share on other sites More sharing options...
supra_ufo Posted December 3, 2013 Share Posted December 3, 2013 It does say this on the hyperlink though.. Cons: Crap FCDs scale the airflow input so that when the stock sensor hits 1.25bar (it's maximum) the ECU gets a shade under 1.0bar. This also has the effect of scaling the ENTIRE airflow signal so the ECU always receives a lower airflow value than the engine is really getting. Messes up the whole fuelling map towards the lean end of the spectrum and is therefore highly not recommended. Does everyone here have a fcd fitted? Note "Crap FCD" Usually the most common brands used on here are HKS and some other brand, im sure someone will tell you. The other brand is more desired but they are more rare and expensive. Quote Link to comment Share on other sites More sharing options...
Guest lewk Posted December 3, 2013 Share Posted December 3, 2013 Got it, thourght that meant fcd's in general. Cheers Quote Link to comment Share on other sites More sharing options...
drift_bear Posted December 3, 2013 Share Posted December 3, 2013 I fitted and ran the hks fcd on my last supra going bpu and it was fine, like said above get new "specialists". If you have one sitting then get it fitted mate Quote Link to comment Share on other sites More sharing options...
Guest lewk Posted December 3, 2013 Share Posted December 3, 2013 Thanks guys! Apologies for sounding like a complete newbie! There's too many people around who call themselves specialists haha I don't know who to believe! Appreciate it. Quote Link to comment Share on other sites More sharing options...
drift_bear Posted December 3, 2013 Share Posted December 3, 2013 Your in the right place for supra specialists now Quote Link to comment Share on other sites More sharing options...
tony tt Posted December 3, 2013 Share Posted December 3, 2013 I think it's channel 9 on the FCD. That right? Quote Link to comment Share on other sites More sharing options...
drift_bear Posted December 3, 2013 Share Posted December 3, 2013 I think it's channel 9 on the FCD. That right? Yeah iirc Quote Link to comment Share on other sites More sharing options...
Ian C Posted December 5, 2013 Share Posted December 5, 2013 I've only heard of the HKS FCD's doing the MAP scaling. The old Thor ones worked fine as they just clamped the signal before 1.0bar of boost. I'm not sure what's out there that works these days though. Quote Link to comment Share on other sites More sharing options...
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