TurboBrett Posted November 6, 2007 Share Posted November 6, 2007 i have been busy playing with my supra trying to get it to misfire when both turbo's are online as it was starting to pi$$ me off and i have come across what i think is the problem but i need some info from you ppl who know more about the engine/mapping (stuff? ) from the start the 1st turbo boosts nicely to about 6psi (sould be about .6 bar ie 8 or 9psi right?)but both only to 9.5 - 10 psi, i checked all over for leaks, found it to be the bov it is easyer to blow thru when it should be holding boost than what it is when it should be recirc'ing it - i thought the ecu must pick up the boost levels before the dumpvalve (seeing the boost before it is 'blead' of by the dump valve) and over fueling silly, would also fit in with the mpg figure i just got:sly: BUT on the way home from work i was thinking isnt it only the uk's that have map sensors and other have tps? so..at a set rpm and set tp it will give a 'set' fuel and cannot tell the boost is lower than it sould be? so over fuel? you still following me? cos idont think i am i have de-re-circed the stock valve, and it does leak loads and it has caused the misfire all the time when both tubies are on line up to about 5500rpm when i get a bit chicken and shift up 2 gears and sit on the first turbo:sly: anyway went slightly of track there the questions i have follow:p 1) am i correct does the ecu sence the engine load via a tps (tt j-spec)and so base its fueling off of this and not the actual boost? 2)would the dumpvalve crating such a drop in boost pressure cause the engine to over fuel to the point of missfire? in theory if both the answers are yes then a new dumpvalve should fix the probs:D i know i could block the dumpvalve completely and take for a spin to see if i get full boost and no missfire but just the thought of a full boost liftoff without a dumpvalve:bang: sorry for the uber long post but i am still learning about the awsome engine known as the 2JZGTE and my only knowledge of the two-way turbo system its air in compresser side...out exhaust side (two way ) thank you in advce:D Link to comment Share on other sites More sharing options...
edge Posted November 6, 2007 Share Posted November 6, 2007 Put another stock bov on it and they are cheap too. Also pull your spark plugs out too and give them a check. J-spec's run map sensor and uk's run a maf (correct me if im wrong) Link to comment Share on other sites More sharing options...
TurboBrett Posted November 6, 2007 Author Share Posted November 6, 2007 Put another stock bov on it and they are cheap too. Also pull your spark plugs out too and give them a check. J-spec's run map sensor and uk's run a maf (correct me if im wrong) so i have it wrong there goes my theory map = manifold absolute pressure maf = manifold absolutly ? where to get stock (denso?) dump valve? edit: checked a couple of plugs(omg like trying to get in fort knocks) black ish in the plug bit (cant describe) but white ish on the arm (dont know technical terms but looked good bit blacker than expected aroung the threads) Link to comment Share on other sites More sharing options...
edge Posted November 6, 2007 Share Posted November 6, 2007 so i have it wrong there goes my theory map = manifold absolute pressure maf = manifold absolutly ? where to get stock (denso?) dump valve? maf - as in mass air flow, not sure what map stands for. We may both be barking up the wrong tree. Quick we need a techie Link to comment Share on other sites More sharing options...
TurboBrett Posted November 6, 2007 Author Share Posted November 6, 2007 maf - as in mass air flow, Quick we need a techie make sense..i like:d Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted November 6, 2007 Share Posted November 6, 2007 Yes your J spec has a MAP sensor so it sees boost pressure, ECU has set maps for given load/boost and RPM, the UK also has MFA mass airflow sensor as well as MAP, it sounds to me like your problem is the std dump valve leaking, but you could also have another boost leak, replace the DV and try that first. Link to comment Share on other sites More sharing options...
supra_surj Posted November 6, 2007 Share Posted November 6, 2007 I and many others have had this misfire problem. Check my thread in the mkiv technical for more things to check. Link to comment Share on other sites More sharing options...
TurboBrett Posted November 7, 2007 Author Share Posted November 7, 2007 got home from work today removed and blocked the dumpvalve, took it for a spin and it now boosts at the right pressure ... but still the missfire problem:( altho i noticed it will missfire at bang on 10spi if i hold the boost below this with my right foot it doesnt miss, usualy a boost related misfire is down to the plug heat or gap isnt it? i have read some where not to change the plug gap on supra's? so new plugs? off to read up on the faq i was on last night:sly: Link to comment Share on other sites More sharing options...
heckler Posted November 7, 2007 Share Posted November 7, 2007 have you tried changing the plugs?! Link to comment Share on other sites More sharing options...
TurboBrett Posted November 7, 2007 Author Share Posted November 7, 2007 have you tried changing the plugs?! no i have had 2 out tho to cheak the colour, thought it was running silly rich but they didnt look too bad (with unleaded u cant realy tell ayway) Link to comment Share on other sites More sharing options...
Ian C Posted November 8, 2007 Share Posted November 8, 2007 Your misfire will be plug gap or coil pack related. Change the plugs to some NGKs as detailed in the FAQ, it's under £15 for a full set. If it still misfires it may well be coil packs and that's rathermore expensive. Your BOV needs replacing, several people will be able to flog you a used but good one for £notmuch. A j-spec car uses a MAP sensor, Manifold Absolute Pressure. It measures the pressure in the plenum. The UK specs and VVTis use a MAF, a Mass Air Flow sensor which works out airflow by how much voltage it takes to keep a wire at a fixed temperature while the intake air flows over it. -Ian Link to comment Share on other sites More sharing options...
TurboBrett Posted November 8, 2007 Author Share Posted November 8, 2007 Your misfire will be plug gap or coil pack related. Change the plugs to some NGKs as detailed in the FAQ, it's under £15 for a full set. If it still misfires it may well be coil packs and that's rathermore expensive. Your BOV needs replacing, several people will be able to flog you a used but good one for £notmuch. A j-spec car uses a MAP sensor, Manifold Absolute Pressure. It measures the pressure in the plenum. The UK specs and VVTis use a MAF, a Mass Air Flow sensor which works out airflow by how much voltage it takes to keep a wire at a fixed temperature while the intake air flows over it. -Ian plugs all changed misfire has gone, bar tiny tiny pop at about 5000rpm but the coil pack clips an 1st is fubar .... and the rest of them aint too cleaver so i hope that new connectors will fix this hope that will be the end of it because about £300 for coilpacks i cant afford Link to comment Share on other sites More sharing options...
edge Posted November 9, 2007 Share Posted November 9, 2007 Glad its nearly done. Had a missfire on mine due to dodgy coil pack connectors. Can be had from traders on here for about £5 each and easy to change. If your not sure there is a step by step guide on here too. Link to comment Share on other sites More sharing options...
TurboBrett Posted November 9, 2007 Author Share Posted November 9, 2007 Your misfire will be plug gap or coil pack related. Change the plugs to some NGKs as detailed in the FAQ, it's under £15 for a full set. If it still misfires it may well be coil packs and that's rathermore expensive. Your BOV needs replacing, several people will be able to flog you a used but good one for £notmuch. A j-spec car uses a MAP sensor, Manifold Absolute Pressure. It measures the pressure in the plenum. The UK specs and VVTis use a MAF, a Mass Air Flow sensor which works out airflow by how much voltage it takes to keep a wire at a fixed temperature while the intake air flows over it. -Ian thank you for your help ian, much appreciated:) Glad its nearly done. Had a missfire on mine due to dodgy coil pack connectors. Can be had from traders on here for about £5 each and easy to change. If your not sure there is a step by step guide on here too. did the miss fire on yours feel like it was just trimming the power down because the one on mine u cant realy tell un less you got good ears and know to listen for it. the coil pack connectors have just been ordered from Whifbitz, very good price:d i will keep u up dated lol:innocent: Link to comment Share on other sites More sharing options...
supra_surj Posted November 9, 2007 Share Posted November 9, 2007 If you dont mind me asking how much were the coil pack connectors? Just incase ive got the same problem. Surj Link to comment Share on other sites More sharing options...
TurboBrett Posted November 10, 2007 Author Share Posted November 10, 2007 you have a pm:) Link to comment Share on other sites More sharing options...
TurboBrett Posted November 10, 2007 Author Share Posted November 10, 2007 these are my connectors... as i found them:( Link to comment Share on other sites More sharing options...
edge Posted November 10, 2007 Share Posted November 10, 2007 did the miss fire on yours feel like it was just trimming the power down because the one on mine u cant realy tell un less you got good ears and know to listen for it. the coil pack connectors have just been ordered from Whifbitz, very good price:d i will keep u up dated lol:innocent: I changed the plugs first and that helped alot, then it was just noticable still but still annoying. But yes power was slighlty down as you know your car just dont feel quite right still. Link to comment Share on other sites More sharing options...
edge Posted November 10, 2007 Share Posted November 10, 2007 http://www.mkivsupra.net/vbb/showthread.php?t=61141 Link to comment Share on other sites More sharing options...
TurboBrett Posted November 13, 2007 Author Share Posted November 13, 2007 just got my connectors today, will be fitting them next monday, not noticed the misfire much resently tho...well not realy been giving it much stick trying to do my bit for the planet:sly: well i do have to think of the wallet aswell:innocent: Link to comment Share on other sites More sharing options...
TurboBrett Posted November 19, 2007 Author Share Posted November 19, 2007 well, fitted the coil pack connectors today, took the car for a spin and no missfire at all ... pulls soo much stronger off boost, generaly feels better all round it feels less slugish on pick up aswell;). Now when it comes on boost also got another 4 pounds of boost to play with:d thanks to new dumpvalve:p the HKS Super-sqv highly recomended...pain to fit because of its size but worth it:eyebrows: Link to comment Share on other sites More sharing options...
jaymdee Posted November 19, 2007 Share Posted November 19, 2007 Well done. Always pleasing to get a little job completed successfully Link to comment Share on other sites More sharing options...
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