Post lockdown problem

[clandyuk]

Originally Posted by Laird Scooby

As both wires that supply the injectors are commoned (greens to greens, greys to greys) they all fire at the same time - this is called Full Group or "batch-fire" injection and is common to most Volvo models from 1986 to ~1998. There are some exceptions .

This is what i had difficulty in understanding - they all fire at the same time! My thinking was that they should fire only on the intake stroke. Now you've drummed it into my head, of course, I now realise its basically the same as a carburettor in that the fuel is delivered to the inlet valve and is then inhaled when the valve opens. So delivery "en masse" is the only way and the "wait time" is measured in milliseconds.
I can now sleep easy. Thanks for your forbearance.

Andy

[Laird Scooby]

Originally Posted by clandyuk

This is what i had difficulty in understanding - they all fire at the same time! My thinking was that they should fire only on the intake stroke. Now you've drummed it into my head, of course, I now realise its basically the same as a carburettor in that the fuel is delivered to the inlet valve and is then inhaled when the valve opens. So delivery "en masse" is the only way and the "wait time" is measured in milliseconds.
I can now sleep easy. Thanks for your forbearance.

Andy

Almost but not quite, the injection time is a few mS with a longer dwell time at low rpm and a longer injection time at higher rpm. This goes hand in hand with higher fuel pressure controlled by manifold vacuum to give increased fueling at high load/engine speed.

[clandyuk]

Originally Posted by Laird Scooby

Almost but not quite

Aww, give me a break. Mine was the layman's description, not the engineer's!
All's well that ends well.

Cheers
Andy

[Rversteeg]

By joining #1/#2 injector plugs they now both run on the same fire cracker. Not sure what this will do on the long run.

[Laird Scooby]

Originally Posted by Rversteeg

By joining #1/#2 injector plugs they now both run on the same fire cracker. Not sure what this will do on the long run.

Good point Rob, i forgot about that! I was concentrating on the fueling and forgetting the electronics.

[clandyuk]

Originally Posted by Rversteeg

By joining #1/#2 injector plugs they now both run on the same fire cracker. Not sure what this will do on the long run.

V Good point. Think I'll run a wire from #1 back to the firecracker outside the loom and revert #2 back to be normal operation, to be on the safe side.
Thanks for pointing this out.

[clandyuk]

Originally Posted by Rversteeg

You have narrowed your problem down to the individual 12V feed wire of injector number 1....snip

As it was a nice day, I decided to do a "proper job" and follow your detailed reply rather than my hit 'n miss bypass approach!
Just as well I did. I checked the continuity from #1 injector back to C132 (back of connector) and to my surprise all was well - no break.
After silently apologising to Mr Mouse - and, NO, you're not getting your nut stash back, I then was worried that the problem was in the unobtainable Ballast resistor.
Prised the connector apart to be presented with

I removed the Ballast resistor to the bench and cleaned the connectors and also checked the resistance from the Blue wire terminal to the four others (Green wires) and all came back with the same resistance. Phew, nothing to worry about here.
I then cleaned as best I could the plug side and reconnected everything.
Checked #1 injector green wire with ignition on and Houston, we have POWER.
Engine started and we're back to all 4 cylinders.
So many thanks again for your detailed analysis of how to pinpoint the actual problem. Lesson learned - be methodical and don't assume!

[Laird Scooby]

Originally Posted by clandyuk

As it was a nice day, I decided to do a "proper job" and follow your detailed reply rather than my hit 'n miss bypass approach!
Just as well I did. I checked the continuity from #1 injector back to C132 (back of connector) and to my surprise all was well - no break.
After silently apologising to Mr Mouse - and, NO, you're not getting your nut stash back, I then was worried that the problem was in the unobtainable Ballast resistor.
Prised the connector apart to be presented with

I removed the Ballast resistor to the bench and cleaned the connectors and also checked the resistance from the Blue wire terminal to the four others (Green wires) and all came back with the same resistance. Phew, nothing to worry about here.
I then cleaned as best I could the plug side and reconnected everything.
Checked #1 injector green wire with ignition on and Houston, we have POWER.
Engine started and we're back to all 4 cylinders.
So many thanks again for your detailed analysis of how to pinpoint the actual problem. Lesson learned - be methodical and don't assume!

Usually something simple and almost always, the evidence is there from the start! Well done on tracing and fixing it! When you get five minutes, invest in a tube of silicone grease, pull that plug apart and squirt some in and reconnect the plug - it will keep water out and protect the pins in the plug from corroding again.