Dave Henshall Posted August 16, 2006 Share Posted August 16, 2006 am i right in thinking that the fuel cut defencers work like the pic ive drawn below... so that as the mas airflow increases so does the signal back to the ecu(whether its voltage current or frequency) so if you up the boost and the mass airlow is increas beyond the facotry setting then fuel cut occurs (like it did in my std evo and cossies) so by fitting a fcd you hold the signal to the ecu at a predefined level so that the ecu thinks its lower than it actually is. how does the ecu compensate the fuelling for this is thi is the case. i nkow its got a 02 sensor pre cat, but this will be for closed loop fuelling and normal cruise and idle, not WOT at high boost- cos if it failed it could v quickly do a lot of damage , so the closed loop fuellingmust swicth off when at WOT and the ecu reverts to it load/rpm table and ajusts the injecotr duty cycles accordingly.... how can this happen if the ecu isnt aware of the increased airflow/boost? is there a map sensor aswell as a maf sensor on them. cos the only real way round this on other turbo cars ive owned it to fit new chip and map sensor so that the ecu IS aware of the actual boost levels, or new ecu with revised software that can accept the increased signal form the airflow meter.... help please... whats different to supras, why dont they run lean and melt the pistons when you run more boost than the ecu can see and therefore control the fuellnig for....? Link to comment Share on other sites More sharing options...
Dave Henshall Posted August 17, 2006 Author Share Posted August 17, 2006 bttt Link to comment Share on other sites More sharing options...
geoffvalenti Posted August 17, 2006 Share Posted August 17, 2006 AIUI (and I'm sure that there are lots more qualified than me ) the Supra rus so rich that fuelling is adequate for boost pressures up to a max of 1.2 bar, after that the fuelling needs to be increased. Link to comment Share on other sites More sharing options...
Homer Posted August 17, 2006 Share Posted August 17, 2006 AIUI (and I'm sure that there are lots more qualified than me ) the Supra rus so rich that fuelling is adequate for boost pressures up to a max of 1.2 bar, after that the fuelling needs to be increased. Thats certainly what i've seen over the past week when playing around with boost. Mine has a very slight lean spot at 1.25bar (4.5krpm), but is still rich everywhere else (afr's in the 10s) Link to comment Share on other sites More sharing options...
Ian C Posted August 17, 2006 Share Posted August 17, 2006 Once a fuel cut defender comes into play your injectors are at 100% duty. You now lean the fuelling off by increasing the boost! It's better to run 1.2bar than 1bar in these circumstances, because you'll get the same 'economy' You can trim this effect back with a airflow fudger fuel controller thingy and get some useful power gains (unmeasured apart from 'seat of the pants') -Ian Link to comment Share on other sites More sharing options...
Dave Henshall Posted August 17, 2006 Author Share Posted August 17, 2006 running that rich thuogh cant be good for the engine surely and it will be down on power compared to as near to running stoichiometically correct thought the revs/ boost range.... has anyone ever fitted an comlpete aftermarket ecu to a TT auto and have it properly mapped...? dont anyone take this the wrong way.. it just seems a bit 'cowboyish' compared to what im used to and haver a fair understanding of..... the uk TT has 550 cc injecotrs which must run unbelieveably rich if thats the case, but uit cant as otherwiese if it were that rich the cats would surely burn out with that much overfulling going on...? Link to comment Share on other sites More sharing options...
Homer Posted August 17, 2006 Share Posted August 17, 2006 running that rich thuogh cant be good for the engine surely and it will be down on power compared to as near to running stoichiometically correct thought the revs/ boost range.... has anyone ever fitted an comlpete aftermarket ecu to a TT auto and have it properly mapped...? dont anyone take this the wrong way.. it just seems a bit 'cowboyish' compared to what im used to and haver a fair understanding of..... the uk TT has 550 cc injecotrs which must run unbelieveably rich if thats the case, but uit cant as otherwiese if it were that rich the cats would surely burn out with that much overfulling going on...? Its rich, but I'm sure those guys at Toyota knew what they were doing when they designed it this way - after all the 2JZ-GTE is pretty much the strongest Jap turbo charged engine ever made. Leaning it out allows more power and yes it is a little gung-ho, however thousands have done it and without issue. Mines been running like this for almost 35k miles and still runs perfect. The UK has a different ECU, cam setup, etc. It still runs rich but gives even more boost to play with. Link to comment Share on other sites More sharing options...
Dave Henshall Posted August 17, 2006 Author Share Posted August 17, 2006 so the UK spec TT with a THOR FCD will make more power (safely) than a import one.? is it common to melt pistons on supras, or is this only when someone who doesnt know what they are doing turn the boost up so far without the though of fuelling? Link to comment Share on other sites More sharing options...
Homer Posted August 17, 2006 Share Posted August 17, 2006 so the UK spec TT with a THOR FCD will make more power (safely) than a import one.? Essentially, yes. The turbo's are steel so can handle more boost (the ceramic jspecs have been known to blown themselves to bits after extended high boost 1.3bar+, however some people have run them unlimited for years at 1.6bar). Also due to larger injectors they will not run lean at 1.2bar+ Downside is slower spool, personally I'd have the ceramics any day due to the instant boost. is it common to melt pistons on supras, or is this only when someone who doesn’t know what they are doing turn the boost up so far without the though of fuelling? Very, very, very rare indeed (and then some). The only people that have managed this are due to a genuine fuel fault (Extremely rare) or by numpties that have had bad maps or push the limits too far. Provided the car is mapped and tuned properly the stock block and head can easily manage a reliable 600bhp. Several cars here run this HP without ever having the head off. One even did over 900 rwhp on completely stock block and head - but is now going through a rebuild Link to comment Share on other sites More sharing options...
Dave Henshall Posted August 17, 2006 Author Share Posted August 17, 2006 makes the cossie feel quite inadequte in comparison.... if you run more than a stage 1 chip you need new injectors, sensors, breathers, head gaskets, fuel pumps ect etc... my escos is going up for sale in the not too distant future - its things like that above that do make me feel much better about supras thanks homer Link to comment Share on other sites More sharing options...
JohnA Posted August 18, 2006 Share Posted August 18, 2006 ...the uk TT has 550 cc injecotrs which must run unbelieveably rich if thats the case, ... That would be true if the ECUs were exactly the same, which of course they aren't. The volumetric efficiencies are also different, so such comparisons are speculative at best. The UKSpec has a different AFR profile through the revs and boost map, since it had to conform to different emissions tests. The ECU maps also integrate with the Exh Gas Recirc setup. The UKSpec can run at top gear with the wastegate disconnected and it is still safely rich (bit like the USSpec, which has yet different ECU maps) Link to comment Share on other sites More sharing options...
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