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fuel cut activation RPM setting????


James1436215376
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Ive got the fuel cut option on, but I cant find (if there is even one)the fuel cut activation table to set the RPM level. The problem is when I rev the engine to anything above 3000rpm and then close the throttle, the revs will drop right down past the set idle rpm and the engine will stall. If the G1 LinkPlus doesnt have the activatoin table do I have to disable the fuel cut option to fix the problem, thus negating economy while at cruise and with a closed throttle???

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Most G1 ECU's have an adjustment to set the load (kPa) point at which the overrun fuel cut turns on.  Activation table is only available in G2/G3 ECU's.  The problem you are having is also improved in G2/G3 ECU's through the use of closed loop idle control.  Overrun fuel cut has little effect at cruise as you are usually below the activation RPM anyways.  Is is more for when you are rolling down hills and slowing down on the motorway.  The effect on economy of overrun fuel cut is very minimal.

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Thanks Ashley, so do you have any ideas as to why the engine will drop to such low revs when I lift of the throttle, this mainly only happens when your free revving the engine but the revs still go quite low i.e. dip below 500rpm if I lift off aburptly while the car is at speed regardless of engine temp. My MAP @ idle (op. temp) is a steady 30kpa, fuel clamp is 26kpa and overrun is 33kpa, I observe when I rev the engine to induce the problem that MAP only drops to ~40-45kpa at around when it stalls. When the link was tuned the value of the overrun was 20kpa but the probelm was still evident back then, I changed the overrun value after reading through the manual myself - the displayed overrun value is when the fuel cut is deactivated? i.e below this value fuel is supplied to enable idle should I have the oerrun around 40-45kpa? Theres no help in the linkplus manual that tells you how to setup the fuel cut overrun like there is for the fuel clamp value. Sorry about the 20 questions. Thanks again.

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The truth is that the idle control on that ECU is not as good as it could be.  It is a reasonably old ECU now and things have changed alot since then.  New ECU's have much more sophisticated idle control.  Important things to do to improve your problem are to make sure the throttle stop screw is set near the idle speed you want and that fuel and ignition in the overrun and stall areas are correct.  dont let it get too lean or the timing go too low in those areas...

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Thanks, I realise that the idle is hard to get perfect or close to with the G1. Ive fiddled with the fuel in the row to the left of where the car idles at and increased it to within 5 points of the idle cell, the idle cell is 115 and the box left of it in the 250rpm column was at 90 so now 110. To the right of the idle cell Ive matched the fueling to 115. Ignition wise the idle cell is at 9 and the cell on either side of it is also 9, should I increase these cells a few points and see where it gets me?

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You can try changing the numbers.  It it not necessary to keep the numbers lower on the left, but mor important to set them to the value required to get the correct AFR...  Sometimes a bit more fuel and ignition in the stall zones can act as an anti-stall...

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