xxcat Posted October 8, 2007 Share Posted October 8, 2007 I've been searching a lot but hasn't found the answer... Which strategy is better for fuel cut defencing (emanage etc). A or B? What is your thoughts? Link to comment Share on other sites More sharing options...
TrickTT Posted October 8, 2007 Share Posted October 8, 2007 A! Link to comment Share on other sites More sharing options...
dini_the_owl Posted October 8, 2007 Share Posted October 8, 2007 just clamp your Bc on emanage at 4.6v as it is set to 5.0 from stock Link to comment Share on other sites More sharing options...
xxcat Posted October 8, 2007 Author Share Posted October 8, 2007 But why not "B" with inj. map correction? Link to comment Share on other sites More sharing options...
JamesG Posted October 8, 2007 Share Posted October 8, 2007 But why not "B" with inj. map correction? Because fuel pulse time is not necessarily directly proportional to MAF. Link to comment Share on other sites More sharing options...
xxcat Posted October 9, 2007 Author Share Posted October 9, 2007 I'm not talking about simple proportions... Maybe it's better to use B and properly tuned inj map (emanage could do that as I know). I'm just thinking about possible problems when suddenly there is no more MAF value increase but in the same time more and more air (boost). How the ECU will react? Link to comment Share on other sites More sharing options...
JamesG Posted October 9, 2007 Share Posted October 9, 2007 You might be right. All that happens in scenario A is that the engine runs leaner. Fortunately, the standard fuelling is set fairly rich at the top end, and you're just eating into that margin once above 1 bar. I can't advise whether it's safe to run like this long-term, other than to say I ran my car at a max of 1.2 bar for over five years and never had any problems. Link to comment Share on other sites More sharing options...
ADL Mark Posted October 9, 2007 Share Posted October 9, 2007 A is the better option as you're still using the sensor's original scale. If you're using the other scenario then the whole scale is off and then only to reach the same point anyway. Seems pretty pointless using injector adjustments to then tune this out. Link to comment Share on other sites More sharing options...
Ian C Posted October 9, 2007 Share Posted October 9, 2007 If you have bigger injectors you would be scaling the airflow signal to do a coarse trim down anyway, so you don't need a fuel cut defender in place as well as an E-Manage (in fact depending on the way the E-Manage is mapped it can be a complete disaster if you have one installed still). Correctly sized injectors will never need 100% duty and you reach that at fuel cut. If you don't have bigger injectors then you will need to use the FCD capabilities of the E-Manage although I use a different voltage value than 4.6v. Scaling the airflow signal purely as an FCD strategy on stock injectors is wrong, bad, and dangerous. -Ian Link to comment Share on other sites More sharing options...
xxcat Posted October 9, 2007 Author Share Posted October 9, 2007 In my case I have single turbo, 850cc and E-manage Ultimate... So I need to alter MAF (avoiding fuel cut) and INJ maps anyway... And I'm just trying to find the better way... But it seems to me that scenario A is not ok in my case... Link to comment Share on other sites More sharing options...
Ian C Posted October 9, 2007 Share Posted October 9, 2007 No, you'd use B by default. A is bad as it limits the range of the stock sensor and gives you a slightly harder time mapping the car up to 1.2bar However if you've got a MAF based system, it's a different story the fuel cut is run off a MAP sensor still, but it isn't used for airflow measurement. You can just take the vac hose off it and block it up, tadaaa, no fuel cut -Ian Link to comment Share on other sites More sharing options...
xxcat Posted October 9, 2007 Author Share Posted October 9, 2007 I have euro mkiv with MAF... So the fuel cut will be initiated by MAF and MAP sensors? Link to comment Share on other sites More sharing options...
Ian C Posted October 9, 2007 Share Posted October 9, 2007 Nope, just the MAP. Link to comment Share on other sites More sharing options...
xxcat Posted October 9, 2007 Author Share Posted October 9, 2007 This makes the whole thread useless No need to correct MAF input for Fuel Cut... For MAP I think I'll use the Greddy FCD. Thanks! Link to comment Share on other sites More sharing options...
Thorin Posted October 9, 2007 Share Posted October 9, 2007 you don't need a fuel cut defender in place as well as an E-Manage (in fact depending on the way the E-Manage is mapped it can be a complete disaster if you have one installed still). This makes the whole thread useless No need to correct MAF input for Fuel Cut... For MAP I think I'll use the Greddy FCD. Thanks! Not entirely useless if you listen to the advice given to you. Link to comment Share on other sites More sharing options...
Ian C Posted October 9, 2007 Share Posted October 9, 2007 Such as, perhaps, just removing the hose from the MAP sensor as it costs £0 instead of a Greddy FCC that costs what, £150? -Ian Link to comment Share on other sites More sharing options...
xxcat Posted October 9, 2007 Author Share Posted October 9, 2007 I already have it anyway (greddy) And -> The turbo pressure sensor is used for six different functions by the ECU. The most noticeable is fuel cut for an overpressure condition which is 2.00 kg/cm2 absolute pressure, or 0.97 kg/cm2 gauge (28.45 psia, 13.75 psig). Fuel cut is an extreme measure invoked by the ECU when it detects boost over 2.00 kg/cm2 absolute, AND throttle position 20 degrees or more AND engine speed over 2400 rpm. It shuts down the engine until the boost drops back below the 2.00 kg/cm2 threshold, and lights up your MIL (malfunction indicator light). The other turbo pressure sensor functions are exhaust gas bypass valve control, idle speed anticipation, exhaust gas recirculation (EGR) control, fuel pump voltage selection, and evaporative emissions control ... according to info on mkiv.com Link to comment Share on other sites More sharing options...
Thorin Posted October 9, 2007 Share Posted October 9, 2007 I already have it anyway (greddy) And -> ... according to info on mkiv.com Ok fine then, why not fit two, one for resilience. Link to comment Share on other sites More sharing options...
xxcat Posted October 9, 2007 Author Share Posted October 9, 2007 Don't see any logic in your post.. Do you mean that all those functions based on output of MAP sensor is useless? For example fuel pump voltage selection. Link to comment Share on other sites More sharing options...
Ian C Posted October 9, 2007 Share Posted October 9, 2007 I remove the MAP sensor on JBs car to defeat fuel cut but it was single turbo'd up so the sequential stuff was irrelevant. Didn't notice a fuelling issue with it not switching to 12v. EGR pah who has that -Ian Link to comment Share on other sites More sharing options...
dini_the_owl Posted October 9, 2007 Share Posted October 9, 2007 I dont see how you could use option b anyhow, what happens when your map sensor sends out its max voltage to the ecu and in turn fuel cut happens? (since it is based on the pressure of the system) unless you disconnect it like ian mentioned your still going to reach the same point on the map scale no matter if you trim down injectors or not? Link to comment Share on other sites More sharing options...
ADL Mark Posted October 9, 2007 Share Posted October 9, 2007 It rescales it so that you in effect won't reach fuel cut. Link to comment Share on other sites More sharing options...
dini_the_owl Posted October 9, 2007 Share Posted October 9, 2007 Re scales what? injectors or pressure sensor, whether your injectors are at 50 percent or 90 percent if your map sensor reaches its pressure point of fuel cut it still happens? Link to comment Share on other sites More sharing options...
xxcat Posted October 9, 2007 Author Share Posted October 9, 2007 I have euro mkiv with MAF... So the fuel cut will be initiated by MAF and MAP sensors? Nope, just the MAP. This makes the whole thread useless No need to correct MAF input for Fuel Cut... For MAP I think I'll use the Greddy FCD. Thanks! Link to comment Share on other sites More sharing options...
ADL Mark Posted October 9, 2007 Share Posted October 9, 2007 Re scales what? injectors or pressure sensor, whether your injectors are at 50 percent or 90 percent if your map sensor reaches its pressure point of fuel cut it still happens? It rescales the output voltage of the sensor against the pressure it sees. So that for instance if before 1.2bar = 5V now 1.2bar= 4.5V and 1.6bar = 5V. It's got nothing to do with injector duty. Link to comment Share on other sites More sharing options...
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