Formula Renault, Megane Engine not Firing

[AJR93RT]

Hello all,

I'm trying to help a college get a Formula Renault up and running for this season but they are having a few issues with the engine. They reccently purchased a Renault Megane engine along with the ECU and loom. They were told it was running fine on removal.

They have installed the engine but can not get it to fire up. There is no fuel being injected by the injectors and no spark from the spark plugs. They have a trace from the crank position sensor which is giving out 0.8V when gapped by 1mm to the trigger wheel. This increases to 2V when gapped to 0.8mm.

The trigger wheel, flywheel, ECU and loom are all stock megane items. They have had the injectors working when operating them manually. So it seems like there is no signal from the ECU to the spark plugs / injectors.

The few questions I have are:-

1. What is the correct output for the crank position sensor in volts?

2. Is there likely to be an immobiliser that requires decoding on the ECU before it is seperated from the car?

3. Could it be a fault ECU?

4. Any other ideas on what it might be or what they can try?

Thanks Adi

 

[Icarus]

Hi Adi,

To identify if you have a useable crank signal you really need a scope on it so you can see the waveform. A voltage reading from it just means it's doing something, not neccesarily the right something

If you have a good crank signal and the loom buzzes back from sensors/actuators okay then it's likely to be ECU/Immobiliser related.

What engine is it exactly? As a relatively recent OEM ECU might not like running with half the sensor pack missing (i.e. low rev limit due to missing wheel speed sensor or similar).

Cheers
Matt

 

[AJR93RT]

It's an F7R from an early megane, they used a scope which showed them the correct wave signal, it was just the voltage output at trigger I wasn't sure about. I'm starting to think it's an ECU or immobiliser issue.

 

[Fred@BTM]

Which college is it?

 

[AJR93RT]

West Anglia!

 

[sideways danny]

megane ECU is coded, so the immobiliser is almost certainly your problem

 

[Anonymous]

Did you get the UCH?

 

[hmh]

I thaught if you swap ECU and use keys from the engine donor, it should start, isn't it?
If it's not ECU I'd check relay giving power to spark plugs and petrol pump. Use a tester or listen for a click sound when key is turned.