ECU injector light operating principle.

[Gwyn]

Hi guys, can anyone tell me with 100% certainty what method the ECU uses to determine there's an injector fault, so it then lights the injector warning light. Is it measuring the resistance of the injector coils, or using some other method?

Is it technically possible to have a blocked or sticking injector, but the warning light not illuminated? My 1.6 Brava is firing on 3. The injector's been changed, ( after which the warning light went off) , the plug is sparking on the defective cylinder, disconnecting the injector loom and spraying easy-start into the air inlet makes it run on 4 for a few seconds, so it's fuel and not a stuck valve. I've checked the injector loom to the ECU, stripped the ECU and checked that the 4 injector trigger transistors are OK, and their connections to the edge connector are OK.

Any info gratefully received!

Thanks,

Gwyn

 

[Sven]

Hard to say, but per your description the problem is in the wiring, better said signal ain't coming to the injector.

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[Gwyn]

Thanks Sven!

Many thanks for the reply Sven ( injector diagram is interesting too). Wiring is OK all the way from injector plugs to ECU, and connectors were cleaned with Kontakt 60. I may get the injector rail out today if the weather is ok, and check injector is functioning by toggling some volts to it and feeding it with isopropyl from an aerosol nozzle. (I know not to apply 12v to the injector for more than an instant at a time.)

 

[Gwyn]

Hmmm

I stripped it this afternoon to get at the injectors.Then had a thought and reconnected the fuel lines.With the fuel rail connected, but lifted to the side of the engine so I could see the inside of the manifold, I attached wires to the suspect injector's connector using crimps, and left the others unconnected electrically.

Turned the ignition on to get the fuel pressure, then flicked 12v to the suspect injector - result instant nice spray pattern.

I'm now wondering if it's maybe something silly like an iffy plug lead... and the Easy Start test conned me because of compression-ignition...?

Cheers,

Gwyn

 

[Sven]

Could be, the 1.6 has long spark plug connectors, if the inside is bad (corroded, not gripping right) the spark is to weak and insufficient. IMO change the plugs, no matter if you changed them already as you may have a bad spark plug, then proceed to leads.

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[Gwyn]

Injector after all

It was actually the injector - it started OK then struck open....I discovered this next day because it wouldn't start - cylinder full of fuel. Now have replaced injector again and running on 4 - but have started new thread this evening as the mixture is way too rich now....

Cheers,

Gwyn