Hi Guys,

I have a problem with the idle with standalone ECU.

The car was mapped, idle was fine, but occassionally the idle just disappears!

It was mapped, that the stapper "grabs" the revolution at 1300rpm, and then it reduces it to 900.

For some odd reason, when I drive the car, on the first few miles it's just perfect, but slowly, the idle gets worse, it goes down.

At the end it's visible that the stepper tries to correct the idle speed, and it "grabs" it at 1300 (just as mapped), but it looses it immeditely and the engine stalls.

When this happens, it will stay like this as long as I don't switch off and back on the ignition.

(usually I just restart the engine with the clutch, if the car is still rolling)


When the IGN is OFF and ON, it's okay for around 1-2 times, and it gets worse and worse - idle speed goes down and down, and at the end it fails to keep it up, ang engine stalls again!


One thing we found, that when the ignition is off, the fuel pump is primed 1-2 times, and during this short period the ECU receives +12V - when VEMSTune is switched on, the ECU comes alive for that short period, and then it comes out.
During this, the stepper goes out, and then goes back. But sometimes the fuel pump priming period is shorter than the in-out movement time of the stepper, so it stops somewhere middle.



Could these two be realted to each other?



Stepper is clean - and I've tried with an other, but it's still the same -, housing is is clean, wiring is OK, mapping is OK.

The car has the original wiring loom, with a plug and play VEMS ECU (so it connects to the original ECU plug), with the latest firmware, mapped for E85.


What the heck could cause this??? I'm a bit lost!


And... how could I disable the fuel pump priming, when the ignition is off? The car did that before the ECU, I guess that's done via the main relay.

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