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Engine harness rewire, now won’t start.

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Link Fury - Renault Megane F4R, using Clio 182 cams therefore no cam pickup/signal present. It was mapped originally to suit this.

 

I’ve recently rewired my engine harness, with no changes to sensor types or ECU mapping etc. When attempting to start the engine it cranks but doesn’t fire.

PCLink displays no Engine Speed (RPM). I’ve double checked everything I’ve done and it all appears to be okay. Sensor is standard Renault Megane F4R with resistance of 280 ohms which seems fine. Continuity is good between sensor and ECU. 

Previously it was grounded through ‘sensor ground’ but is now grounded through ‘shielded ground.’ I don’t believe this is an issue as a continuity test shows they’re connected in the ECU.

The engine ran perfectly fine prior to the harness change.

Can anyone offer advice as to what I should be looking for?

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I’ve attached the scope capture. Weirdly it’s now registering around 250rpm when cranking, I did add a jump box so perhaps it was a bit upset if the battery was a little low before.

Anyway, it still doesn’t start and it has recorded 2x trigger 1 err counter. I’m not sure whether that’s indicating an error or it’s just recognising it hasn’t started.

Perhaps the crank circuit is okay and something else is causing the non start?

 

Edit: That’s connecting to the signal and shielded ground, the scope reading is the same when connected to body ground.

 

4DB6BAED-4EC8-4DEE-B68A-C31F376BBA6F.jpeg

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Hi Richard,

Apologies but I'm quite inexperienced with this... I've opened Trigger Scope but I'm struggling to get it to display anything. What do I need to do to set it up to log the trigger signal?

Thanks

Ollie

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Okay so I've worked out the trigger scope, so here it is...

Thanks again for your help, let me know what you think on this.

 

image.png.e4f9c4529d6ff61b2078394732f96291.png

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I don't know your platform but on my z33, also after a harness rebuild, engine rebuild, and different turbo setup I had starting issues.  Cranked fine, I had fuel pressure and I checked/double checked multiple times along the way of the harness rebuild and it ended up being my camshaft position sensors.  

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Hi BeallJK,

I've actually resolved the non start issue now, there was an issue with the igniter earth. I'm running with wasted spark and semi injection so no cam sensor.

However, now it runs with a significant misfire but doesn't appear to be one particular cylinder. Carried out all the usual checks but to no avail. Hopefully someone can confirm whether the triggerscope is good or not, could still be the running issue I guess. Although it won't fire with switched polarity.

Ollie

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Hi Adam. Good news, I’ve located the issue... there was a vacuum leak near the map sensor. Fault now resolved, thank you for your input.

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