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700/900 Series General Forum for the Volvo 740, 760, 780, 940, 960 & S/V90 cars |
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May 31st, 2020, 15:58 | #11 | |
940 LPT Est/V70XC AWD
Last Online: Mar 23rd, 2024 13:25
Join Date: Dec 2003
Location: Waterlooville
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Quote:
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?? |
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May 31st, 2020, 16:20 | #12 | |
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Quote:
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.
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May 31st, 2020, 23:32 | #13 | |||
940 LPT Est/V70XC AWD
Last Online: Mar 23rd, 2024 13:25
Join Date: Dec 2003
Location: Waterlooville
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Quote:
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. Quote:
Quote:
Thanks for your input so far. |
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Jun 1st, 2020, 20:15 | #14 |
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Last Online: Mar 1st, 2024 08:41
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Location: London
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https://www.volvoforums.org.uk/showthread.php?t=302381
Worth a read. Shows the led for the injectors
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Volvo 940 19T, Charge cooled, Chipped. |
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Jul 6th, 2020, 14:26 | #15 |
940 LPT Est/V70XC AWD
Last Online: Mar 23rd, 2024 13:25
Join Date: Dec 2003
Location: Waterlooville
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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! |
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Jul 6th, 2020, 15:32 | #16 | |
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Quote:
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Jul 6th, 2020, 16:52 | #17 |
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Last Online: Yesterday 16:35
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Location: Amersfoort (NL)
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Faulty wiring / connector
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. |
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Jul 6th, 2020, 19:36 | #18 | |
940 LPT Est/V70XC AWD
Last Online: Mar 23rd, 2024 13:25
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Location: Waterlooville
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M'Laird,
Quote:
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 |
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Jul 6th, 2020, 19:45 | #19 | ||
940 LPT Est/V70XC AWD
Last Online: Mar 23rd, 2024 13:25
Join Date: Dec 2003
Location: Waterlooville
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Quote:
Quote:
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 |
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Jul 6th, 2020, 20:18 | #20 | |
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Last Online: Yesterday 23:44
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Quote:
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.
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