RZtwin Posted March 17, 2020 Share Posted March 17, 2020 Hello, I just installed Brian crower 272 camshafts in my 94 Supra TT RZ 2jzgte, still on stock ecu. The car starts then dies, unless I hold gas pedal down slightly at start up. Is this normal? Quote Link to comment Share on other sites More sharing options...
Mo Reviews Posted March 17, 2020 Share Posted March 17, 2020 You need to get your engine mapped bud... Quote Link to comment Share on other sites More sharing options...
RZtwin Posted March 17, 2020 Author Share Posted March 17, 2020 You need to get your engine mapped bud... Really hoping that's all it is. I have a Haltech elite 2500 going in next winter along with single turbo kit and fuel system. Will get it tuned after I install all the parts. Thank you! Quote Link to comment Share on other sites More sharing options...
Mike2JZ Posted March 17, 2020 Share Posted March 17, 2020 Stock ecu will shit its pants trying to run aggressive 272s, the fueling requirements are completely different to stock cams that have no overlap. You will need to adjust your idle to 1000 or maybe more to allow it to run. You can so this using the throttle set screws. If your ecu hasn't been plugged in for a while then it will need some time for the iacv to find its position, so you can try helping it stay alive with the throttle until engine is warm and see if iacv cam sort out the idle, if not use set screw. Also make sure your have a way of monitoring AFR Quote Link to comment Share on other sites More sharing options...
Mo Reviews Posted March 17, 2020 Share Posted March 17, 2020 There's a chance you could be running quite lean with all that extra air? Quote Link to comment Share on other sites More sharing options...
Lee P Posted March 17, 2020 Share Posted March 17, 2020 There's a chance you could be running quite lean with all that extra air? Actually the other way round It will cause it to run rich around the idle area, also double check your timing and make sure belt is on ok Quote Link to comment Share on other sites More sharing options...
Mo Reviews Posted March 17, 2020 Share Posted March 17, 2020 Actually the other way round It will cause it to run rich around the idle area, also double check your timing and make sure belt is on ok I'm quite surprised actually, I thought the longer duration cams would effectively allow more air in to the combustion chamber thus leaning out the engine? How does this work? Does the ECU over-compensate by dumping more fuel in? Quote Link to comment Share on other sites More sharing options...
Lee P Posted March 17, 2020 Share Posted March 17, 2020 I'm quite surprised actually, I thought the longer duration cams would effectively allow more air in to the combustion chamber thus leaning out the engine? How does this work? Does the ECU over-compensate by dumping more fuel in? Will need more fuel up top but less around idle because of the overlap on the cams. Which is why cams are a trade off and shift power bands, essentially the engine has less compression at idle so more fuel wastage Quote Link to comment Share on other sites More sharing options...
Style Posted March 17, 2020 Share Posted March 17, 2020 More air will equal less vacuum so the MAP sensor reading will give the illusion the car is under load. The ECU will add fuel to compenate for this and run rich. Quote Link to comment Share on other sites More sharing options...
Mo Reviews Posted March 18, 2020 Share Posted March 18, 2020 Will need more fuel up top but less around idle because of the overlap on the cams. Which is why cams are a trade off and shift power bands, essentially the engine has less compression at idle so more fuel wastage More air will equal less vacuum so the MAP sensor reading will give the illusion the car is under load. The ECU will add fuel to compenate for this and run rich. Aha, thank you for the explanation chaps. Quote Link to comment Share on other sites More sharing options...
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