Volvo Community Forum. The Forums of the Volvo Owners Club

Forum Rules Volvo Owners Club About VOC Volvo Gallery Links Volvo History Volvo Press
Go Back   Volvo Owners Club Forum > "Technical Topics" > 700/900 Series General
Register Members CarsBlogs Help Calendar Mark Forums Read

Notices

700/900 Series General Forum for the Volvo 740, 760, 780, 940, 960 & S/V90 cars

Information
  • VOC Members: There is no login facility using your VOC membership number or the details from page 3 of the club magazine. You need to register in the normal way
  • AOL Customers: Make sure you check the 'Remember me' check box otherwise the AOL system may log you out during the session. This is a known issue with AOL.
  • AOL, Yahoo and Plus.net users. Forum owners such as us are finding that AOL, Yahoo and Plus.net are blocking a lot of email generated from forums. This may mean your registration activation and other emails will not get to you, or they may appear in your spam mailbox

Thread Informations

Post lockdown problem

Views : 251

Replies : 13

Users Viewing This Thread :  

Reply
 
Thread Tools Display Modes
Old May 29th, 2020, 15:48   #1
clandyuk
940 LPT Est/V70XC AWD
 

Last Online: Jun 1st, 2020 23:49
Join Date: Dec 2003
Location: Waterlooville
Default Post lockdown problem

Hi everyone, my ancient 940 2.3 LPT (97 MY) has been sitting idle for these past month(s).
Started it yesterday and whilst it started on the button, it's only running on 3 cylinders! Natch, it was running fine before lockdown.
Pulled leads and it's #1 that's doing nothing.
Checked for spark - yes, good spark.
I pulled the injector plugs on #1 and #2 and tested for voltage on the 2 pins with ignition on. #1 showing 11.98V on one and 0.48V on t'other. #2 is showing 11.98V on both.
So from that I assume something is amiss but I have no experience on Fuel Injection and am a bit unsure how to proceed now.
Any suggestions, please?
Thanks.
Andy
clandyuk is offline   Reply With Quote
The Following User Says Thank You to clandyuk For This Useful Post:
Old May 29th, 2020, 17:22   #2
TonyS9
Premier Member
 

Last Online: Yesterday 02:50
Join Date: Jul 2009
Location: Holywood
Default

The fuel ECU pulls the ground side down to zero to actuate the injector, the 12V is permanent (via the radio supression fuel relay).

All the injector leads are connected in paralell, they should all show identical voltages, and should both show close to 12V if you have at least 1 injector coil still attached.

Seems you have a faulty loom.
TonyS9 is offline   Reply With Quote
The Following 2 Users Say Thank You to TonyS9 For This Useful Post:
Old May 29th, 2020, 17:41   #3
Chooch84
940 Noob
 

Last Online: Yesterday 19:13
Join Date: Jul 2015
Location: Birmingham
Default

Swap the injectors about, you might have a blocked injector. It's a bit of a messy job, especially if the fuel rail is still pressurised (release the pressure using the valve found at the bottom of the fuel rail). You could also check the resistance of each injector. Assuming you have the original 0 280 150 804 injectors, resistance should between 2-3 ohms per injector.

If you're going to remove the injectors, it would be worth flashing a torch into the tops of them to see if the filter basket looks clogged.
__________________
96 945 Classic 2.3 LPT with some mods...
To do: Install upper brace, Catch can, install sound deadening (50% done), Fit electric leather seats, repaint! List is endless...

16 BMW 330e

Last edited by Chooch84; May 29th, 2020 at 17:46.
Chooch84 is offline   Reply With Quote
The Following 2 Users Say Thank You to Chooch84 For This Useful Post:
Old May 29th, 2020, 18:25   #4
clandyuk
940 LPT Est/V70XC AWD
 

Last Online: Jun 1st, 2020 23:49
Join Date: Dec 2003
Location: Waterlooville
Default

Quote:
Originally Posted by TonyS9 View Post
The fuel ECU pulls the ground side down to zero to actuate the injector, the 12V is permanent (via the radio supression fuel relay).

All the injector leads are connected in paralell, they should all show identical voltages, and should both show close to 12V if you have at least 1 injector coil still attached.

Seems you have a faulty loom.
Ah, that might be the problem. You've just jogged my memory that I had to throw out a pesky field mouse from BOTH of my Volvos. Chucked him out of the bonnet lining on the 940 and the cheeky s*d moved into the V70.
I left the linngs out and then had to suffer clouds of steam from water evaporating on the bonnet when it rained and I was stopped in traffic.
Will investigate with a torch. He/She might be back as a result of the lockdown.
Just to clarify - should both injector plug wires show the same Voltage when grounding them via the Voltmeter or at least the same Voltages for each separate lead wire IYSWIM?
clandyuk is offline   Reply With Quote
The Following 2 Users Say Thank You to clandyuk For This Useful Post:
Old May 29th, 2020, 18:29   #5
clandyuk
940 LPT Est/V70XC AWD
 

Last Online: Jun 1st, 2020 23:49
Join Date: Dec 2003
Location: Waterlooville
Default

Quote:
Originally Posted by Chooch84 View Post
Swap the injectors about, you might have a blocked injector.
Thanks for that. Will check wiring first as it seems it might be a more fruitful avenue given the history.
clandyuk is offline   Reply With Quote
The Following 2 Users Say Thank You to clandyuk For This Useful Post:
Old May 29th, 2020, 22:30   #6
Laird Scooby
Premier Member
 
Laird Scooby's Avatar
 

Last Online: Today 01:21
Join Date: May 2012
Location: Lakenheath
Default

Quote:
Originally Posted by clandyuk View Post
Ah, that might be the problem. You've just jogged my memory that I had to throw out a pesky field mouse from BOTH of my Volvos. Chucked him out of the bonnet lining on the 940 and the cheeky s*d moved into the V70.
I left the linngs out and then had to suffer clouds of steam from water evaporating on the bonnet when it rained and I was stopped in traffic.
Will investigate with a torch. He/She might be back as a result of the lockdown.
Just to clarify - should both injector plug wires show the same Voltage when grounding them via the Voltmeter or at least the same Voltages for each separate lead wire IYSWIM?
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.
Start it up and see if it's back on all 4 pots. If so, there's either dirt on the connector inside the injector plug on the one with the low reading or a break in the cable.

It will help you narrow down the problem more quickly anyway.
__________________
Cheers

Dave

Next Door to Top-Gun with a Rover 827 Sterling and a 765 GLEa V6!
Laird Scooby is offline   Reply With Quote
The Following 2 Users Say Thank You to Laird Scooby For This Useful Post:
Old May 29th, 2020, 23:17   #7
clandyuk
940 LPT Est/V70XC AWD
 

Last Online: Jun 1st, 2020 23:49
Join Date: Dec 2003
Location: Waterlooville
Default

Quote:
Originally Posted by Laird Scooby View Post
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.
Start it up and see if it's back on all 4 pots. If so, there's either dirt on the connector inside the injector plug on the one with the low reading or a break in the cable.

It will help you narrow down the problem more quickly anyway.
I'm liking that idea - brilliant (and easy to do). Will give it a go tomorrow.
Thank you.
clandyuk is offline   Reply With Quote
The Following 2 Users Say Thank You to clandyuk For This Useful Post:
Old May 29th, 2020, 23:59   #8
Laird Scooby
Premier Member
 
Laird Scooby's Avatar
 

Last Online: Today 01:21
Join Date: May 2012
Location: Lakenheath
Default

Quote:
Originally Posted by clandyuk View Post
I'm liking that idea - brilliant (and easy to do). Will give it a go tomorrow.
Thank you.
You're welcome, hopefully it gives a few ponters as to where the problem lies.
__________________
Cheers

Dave

Next Door to Top-Gun with a Rover 827 Sterling and a 765 GLEa V6!
Laird Scooby is offline   Reply With Quote
The Following User Says Thank You to Laird Scooby For This Useful Post:
Old May 30th, 2020, 02:30   #9
TonyS9
Premier Member
 

Last Online: Yesterday 02:50
Join Date: Jul 2009
Location: Holywood
Default

Quote:
Originally Posted by clandyuk View Post
Just to clarify - should both injector plug wires show the same Voltage when grounding them via the Voltmeter or at least the same Voltages for each separate lead wire IYSWIM?
Not sure what you mean, You are not grounding the wires via the multmeter in voltage mode. The multimeter is measuring the voltage difference between 2 points, it doesn't conduct any significant current. Don't ever use current mode if you don't know how to use it, it will just blow the meter.

So with multimeter in voltage mode between chassis ground and either injector pin it should show both as near 12V. An injector just like an open ended coil with 12V at one side. The other side will also be at 12V also because there is no current runing though it. (Vdrop=IR)

If you unplug all the injectors you will see 12V only one 1 pin of the connector, the other side I'm not sure what it will be at because it connected to an open collector output of a power electronic stage in the ECU, it could be at any voltage when its not trying to actuate the injector.
TonyS9 is offline   Reply With Quote
The Following 2 Users Say Thank You to TonyS9 For This Useful Post:
Old May 30th, 2020, 12:53   #10
Laird Scooby
Premier Member
 
Laird Scooby's Avatar
 

Last Online: Today 01:21
Join Date: May 2012
Location: Lakenheath
Default

Quote:
Originally Posted by TonyS9 View Post
If you unplug all the injectors you will see 12V only one 1 pin of the connector, the other side I'm not sure what it will be at because it connected to an open collector output of a power electronic stage in the ECU, it could be at any voltage when its not trying to actuate the injector.
If it's open collector Tony, it will be in high impedance state so there won't be any voltage on it with the injectors unplugged. Could also be they used MOSFET output stages in which case it will still be high impedance but will switch the injectors quicker with fewer worries about hysteresis.

The +12V will be on the pin with the green wire on the injector plug.
__________________
Cheers

Dave

Next Door to Top-Gun with a Rover 827 Sterling and a 765 GLEa V6!
Laird Scooby is offline   Reply With Quote
The Following User Says Thank You to Laird Scooby For This Useful Post:
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 02:59.


Powered by vBulletin
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.