New to me 940

[sam1]

I wonder if it could be the RSR, attached to the coolant reservoir on mine

[Laird Scooby]

It's possible but what's it doing now?

[sam1]

Towed home, gently brought the clutch up in gear a couple of times and it started and stayed idling for 30s then died. Just to try to give me a bit of vacuum on the brakes if needed whilst being towed.
Once home it started with enough life to let me back it onto the drive then it stalled. Lambda was light then permanent on the dash.
Idle seems normal when it wants to start. When revving any more than incredibly gently it sounds like it is misfiring and then splutters. Sometimes recovers to poor idle sometimes just dies... hmmm.

[Laird Scooby]

Originally Posted by sam1

Towed home, gently brought the clutch up in gear a couple of times and it started and stayed idling for 30s then died. Just to try to give me a bit of vacuum on the brakes if needed whilst being towed.
Once home it started with enough life to let me back it onto the drive then it stalled. Lambda was light then permanent on the dash.
Idle seems normal when it wants to start. When revving any more than incredibly gently it sounds like it is misfiring and then splutters. Sometimes recovers to poor idle sometimes just dies... hmmm.

You need to read the codes then but it also sounds a bit like a blocked cat. That would give the symptoms you've got. You could try crawling underneath and tapping the cat to see if it rattles, if so it's almost certainly blocked but don't mistake a loose heatshield for a cat rattle.

[sam1]

I am not convinced it would be the cat but its a good shout and I will investigate. It will no doubt run fine in the morning as it did after being sat in the garage for a few weeks.
I am going to open up the relays, they look to be original so probably need replacing or re soldering possibly.
The one front left behind the ash tray and the radio suppression relay in the engine bay

[sam1]

Have just opened up the RSR radio suppression relay from on the side of the coolant reservoir to find significant corrosion and oxidation to the pcb. Pic attached. Going go clean and resolder and see if any improvement.
Before removal the car started fine and revved to 3k with no hesitation. Not something I usually do on a cold engine but just wanted to see if it would hesitate which it didn't. Exhaust tailpipe seemed fully flowing

Edit part number on top of casing showing 899931 1323592-1 , 12V/40A. Made in W.-Germany !!

[Laird Scooby]

Originally Posted by sam1

Have just opened up the RSR radio suppression relay from on the side of the coolant reservoir to find significant corrosion and oxidation to the pcb. Pic attached. Going go clean and resolder and see if any improvement.
Before removal the car started fine and revved to 3k with no hesitation. Not something I usually do on a cold engine but just wanted to see if it would hesitate which it didn't. Exhaust tailpipe seemed fully flowing

Edit part number on top of casing showing 899931 1323592-1 , 12V/40A. Made in W.-Germany !!

That would cause exactly the symptoms you've had! Well done for finding it! Looks like you can ignore the blocked cat suggestion now too!

As far as i know, the RSR relays are NLA from Volvo, sometimes they come up secondhand on fleabay but are stupidly expensive. I plan on replacing my RSR (it's working ok at present but is 33+ years old so don't want to risk things!) with a normal, generic 4-pin relay and will be doing a write-up on it with photos.
Won't be for a while yet as it's still too cold and damp outside for me to be out for any length of time.

PS - i just searched gcp.se for 1323592-1 and "No results", in other words, NLA from Volvo.

[sam1]

Originally Posted by Laird Scooby

That would cause exactly the symptoms you've had! Well done for finding it! Looks like you can ignore the blocked cat suggestion now too!

As far as i know, the RSR relays are NLA from Volvo, sometimes they come up secondhand on fleabay but are stupidly expensive. I plan on replacing my RSR (it's working ok at present but is 33+ years old so don't want to risk things!) with a normal, generic 4-pin relay and will be doing a write-up on it with photos.
Won't be for a while yet as it's still too cold and damp outside for me to be out for any length of time.

PS - i just searched gcp.se for 1323592-1 and "No results", in other words, NLA from Volvo.

Thanks Dave. Yes i couldn't find any for sale new anywhere. I think doing your own build is the only option.

Refitted the relay earlier and have done about 12 mile test drive without fault! My speedometer is also now working again.... weird. Must somehow be linked to the RSR.

It really is a nice car, when its working. The engine is so smooth and quiet, even with 176k

[Laird Scooby]

The speedo shouldn't be linked in any way to the RSR but there's always a chance that there's something that's been changed from the circuits i'm familiar with and/or someone has modified something in the past.

Either way a good result, when i get round to changing my RSR i'll post a "How to..." so keep your eyes peeled! As already said, won't be for a while yet though.

[Rversteeg]

The radio interference suppression relay or injector relay is still widely available, though not OEM. In some models this relay is also used for the E-fan.
https://www.estateservices.nl/volvo-...0-940-960.html
https://www.rendcarparts.com/volvo/p...592/RD1323592A
https://www.skandix.de/en/spare-part...rcuit/1009343/
For this price it is not worth trying to revive a used one, I should think, although prices could be higher in the UK and availibility an issue due to your recent decision to "take back control"...