Post lockdown problem

[clandyuk]

Originally Posted by Laird Scooby

Do this simple test - find a short length of wire and bare the ends. Remove injector plugs #1 & #2 and feed one end of the jumper cable (the one you've just bared the ends on) into the grey connector on #1 and the other end into the grey connector on #2 then refit the plugs on the injectors.

Simple to say but impossible (for me) to do, I'm afraid.
What was easier was to make my own little Noid light!! Worked on #2,#3,#4 injectors but nothing on #1.
With ignition on, I then checked the unplugged #1 lead for voltage on Grey wire (+probe to socket; - lead to engine block) - 11.98V.
So from all this I deduce that it's the Green wire that's the problem. Am I correct?
If so, if I bridge connect #1 & #2 Green wires, is that going to blow anything up?
From looking at the wiring diagram, all Greens seem to meet together anyways after the injectors. Also, from what I understand (which I admit is v.little) from reading the Volvo Club FI FAQ, it seems that the injectors are all firing together anyway.
What I need to do is get the car temporarily mobile so I can empty it of all the garden waste in the back before getting it into the garage for a "proper" look around under the bonnet.
Can anyone tell me where the green wire goes after it disappears into the loom that goes down between the inlet manifold and round the gearbox??

[Laird Scooby]

Originally Posted by clandyuk

Simple to say but impossible (for me) to do, I'm afraid.
What was easier was to make my own little Noid light!! Worked on #2,#3,#4 injectors but nothing on #1.
With ignition on, I then checked the unplugged #1 lead for voltage on Grey wire (+probe to socket; - lead to engine block) - 11.98V.
So from all this I deduce that it's the Green wire that's the problem. Am I correct?
If so, if I bridge connect #1 & #2 Green wires, is that going to blow anything up?
From looking at the wiring diagram, all Greens seem to meet together anyways after the injectors. Also, from what I understand (which I admit is v.little) from reading the Volvo Club FI FAQ, it seems that the injectors are all firing together anyway.
What I need to do is get the car temporarily mobile so I can empty it of all the garden waste in the back before getting it into the garage for a "proper" look around under the bonnet.
Can anyone tell me where the green wire goes after it disappears into the loom that goes down between the inlet manifold and round the gearbox??

Link the green wires then between #1 and #2 injector plugs, i should have perhaps added that last night.

They are Full-Group injection or batch-fire as it's also called so all 4 injectors fire at the same time.
Top marks for making your own NOID light, good diagnostics.

As for where they go, they go to the RSR relay, usually on the drivers suspension tower or passenger inner wing.

[clandyuk]

Originally Posted by Laird Scooby

Link the green wires then between #1 and #2 injector plugs, i should have perhaps added that last night.

Got it all wired up and, eureka, all injector sockets when individually disconnected were showing battery voltage on both sides. Started it up and still the same - no change when #1 plug pulled (sob!).
Rechecked wiring and once again #1 Green wire reduced 0.28V. Think my wiring is not up to the job, so am now awaiting Posi-T connectors as I don't want to hack the loom and there isn't much free wire to work with. Delivery mid week'ish so all put on hold until then.

Top marks for making your own NOID light, good diagnostics.

Was quite surprised it worked!

As for where they go, they go to the RSR relay, usually on the drivers suspension tower or passenger inner wing.

Will go searching.

Thanks for your input so far.

[mhuk]

https://www.volvoforums.org.uk/showthread.php?t=302381

Worth a read. Shows the led for the injectors

[clandyuk]

Doesn't time fly.....!
Got the "proper" posilock connectors the other week, but have only got around to re-wiring the errant injector plug.
Connected the green wire from injector #2 to injector #1 and....taaa daa! the car started and is now running on all cylinders. Result.
Can I leave my temporary wiring until such time as I can do a more in-depth analysis of where the wiring "break" actually is or does it mean that #1 and #2 cylinder injectors will be fuelling at the same time....and is this a problem?
Many thanks to all for your input so far. The home straight beckons, I hope!

[Laird Scooby]

Originally Posted by clandyuk

does it mean that #1 and #2 cylinder injectors will be fuelling at the same time....and is this a problem?

Originally Posted by Laird Scooby

They are Full-Group injection or batch-fire as it's also called so all 4 injectors fire at the same time.

As above ^^^^^ it's not sequential injection.

[Rversteeg]

You have narrowed your problem down to the individual 12V feed wire of injector number 1. As you can see in the electrical diagram, all injectors have a common feed from the radio suppression relay 2/12. This is a blue wire running to ballast resistors 20/15. From here there are individual wires running to each injector. To find you problem, you have to look between the ballast resistor 20/15 and the fuel injector (8/6) of cilinder no. 1.
The ballast resistor 20/15 looks like a pack of four fire crackers and is located near the battery. From here four green wires running to connector C132. C132 is a grey 8-pin connector located near the OS side of the bulkhead.
I would first check if connector C132 and the connector on 20/15 are clean.
Then I would measure the resistance of the green wire between terminal 6 of 20/15 and terminal 3 of C132.
Finally I would check the conductivity of the wire between C132 and the injector 8/6.
If this all seems to be in order, the fault can only be in the ballast resistor, although I have never heard of one that had failed.

[clandyuk]

M'Laird,

Originally Posted by clandyuk

#1 and #2 cylinder injectors will be fuelling at the same time....and is this a problem?

Originally Posted by Laird Scooby

it's not sequential injection.

I take to mean that this isn't a problem to leave the two injector green wires connected until I can find the time to ferret along the loom to find....whatever is stopping the flow.
I "think" I've got the gist of how FI works electrically. Am I lucky that the "break" wasn't in the other wire which, I assume, is the ECU trigger to ground to operate the injector?
Thanks again for your help.

Andy

[clandyuk]

Originally Posted by Rversteeg

The ballast resistor 20/15 looks like a pack of four fire crackers and is located near the battery. From here four green wires running to connector C132.

Now I know what I was looking for, it was easy to spot - thanks.

C132 is a grey 8-pin connector located near the OS side of the bulkhead.

Transparent(ish) conector immediately above 20/15 looks to be the one. Has all the right coloured wires. Makes sense as it's a RHD car, not to traverse the engine bay.

I will get round to checking the continuity of the wire, but for the moment my joining #1/#2 injector plugs on the green wire has restored 4 cylinder running, so I move on to the 1001 other jobs on my current list.
Thanks for your input, esp the descriptions.

Andy

[Laird Scooby]

Originally Posted by clandyuk

M'Laird,


I take to mean that this isn't a problem to leave the two injector green wires connected until I can find the time to ferret along the loom to find....whatever is stopping the flow.
I "think" I've got the gist of how FI works electrically. Am I lucky that the "break" wasn't in the other wire which, I assume, is the ECU trigger to ground to operate the injector?
Thanks again for your help.

Andy

Andy - the green wire is +12V from the RSR (Radio Suppression Relay) and feeds all 4 injectors and in certain cases, the Lambda heater as well.

The grey wire on each injector is commoned to the next one and then goes back to the ECU and is thesignal to fire the injectors.

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 .

If the green +ve feed stayed and each injector had a separate wire of differing colours for the fire signal from the ECU, this would be Sequential injection and each injector would fire in order around the time the inlet valve for that cylinder was opening. That allows for more precise metering of the fuel and is quicker to adjust to variations in mixture needs.