Engine cut out and Lambda sensor

[Laird Scooby]

Originally Posted by jlawler

The engine just dies. Not spluttering like a fuel issue. Just dead coasting down the road at 60mph engine being turned over by the vehicle. Rev counter drops to zero.
Feels much more like an electrical/ignition issue than fuel in that it is sudden death (though I know the relay also feeds into the injection system).

I double-checked the fuel pump relay seating.

Thanks I'll try the MAF test.

I'm suspicious because of the previous problems that it related to fixing those.
Hence the Temperature sensor could have been damaged during getting the head reconditioned. It took me a while to track down the previous CPS sensor issue so I would have been messing around with the ignition relay, ignition amplifier etc.
Though I did re-heatsink that at the time.

No need to try the MAF test, the big, really useful clue is "Rev counter drops to zero.". That means one or more of the following :

1. Fuses #11 and/or #13 as listed in my previous post.

2. Faulty CPS

3. Faulty ignition amp module.

On the Mk2 940s (96-on) the coil is fed by one of the fuel pump fuses (can't remember which, had my Kung Flu booster 2 days ago and still have a headache/blurry vision from it so can't delve into the diagram to confirm which fuse but i know one of them) and you're losing ignition coil output. Two possible reasons for this, either the igntion amp module is shot or the power feed or signal to it is lost.

Assuming the CPS is ok (seem to recall you renewed it recently?) that leaves either the fuses as already suggested or the ignition amp module.

https://www.ebay.co.uk/itm/153998310645

Not sure if they'll post to Eire but gives you the part number to find it locally - it's a very popular module (or was!) so i daresay your local motor factor will have one in stock or at least another brand equivalent. Don't forget fresh heatsink compound after cleaning the heatsink when you fit it if it is that.

Try the fuses first though!

[jlawler]

Thanks Tony.
The intermittent nature of the fault makes this a difficult problem.

It runs fine until it doesn't, and when I say fine I mean it seems to be driving better than when I've ever had it.
It starts in under one second, runs great, idles smoothly. Then about 30-60mins in it just dies. No life immediately after the fault occurs (though I didn't check out the rev counter). Where it happens doesn't give me much opportunity to diagnose (though I did get to read the fault code)

If I leave it for about 60s it's Ok again (in that it starts totally normally). Today I drove 30 minutes back home after it died without any problems or any sign of the fault reoccurring.

I've done weeks of driving in between occurrences, but it appears to be getting worse. That's why it going to be painful to diagnose. In some ways, if it just stayed dead it would help. Unless I can see something obviously brocken, the only thing I can see is to swap each item one by one until it stops happening.

[Moomoo]

Could it be an essential , electric component overheating? Coil? Ignition switch?

Is that too simple?

[jlawler]

Yes the CPS is practically new.
I will check those fuses and the feeds to the coil.
If they are Ok I have a spare ignition amp module I can test with.
One bit at a time.

[Laird Scooby]

Originally Posted by jlawler

Thanks Tony.
The intermittent nature of the fault makes this a difficult problem.

It runs fine until it doesn't, and when I say fine I mean it seems to be driving better than when I've ever had it.
It starts in under one second, runs great, idles smoothly. Then about 30-60mins in it just dies. No life immediately after the fault occurs (though I didn't check out the rev counter). Where it happens doesn't give me much opportunity to diagnose (though I did get to read the fault code)

If I leave it for about 60s it's Ok again (in that it starts totally normally). Today I drove 30 minutes back home after it died without any problems or any sign of the fault reoccurring.

I've done weeks of driving in between occurrences, but it appears to be getting worse. That's why it going to be painful to diagnose. In some ways, if it just stayed dead it would help. Unless I can see something obviously brocken, the only thing I can see is to swap each item one by one until it stops happening.

That's why i've suggested what i have, the order to do things etc. Chacnes are the fuses are dirty and overheating cutting the feed to the coil and/or fuel pump but definitely the coil if you have no tacho. However that could also be the ignition amp module but fuses are cheaper and easier to change than the ignition amp.

I wouldn't normally recommend the parts-cannon approach but for the sake of £25 or less, buy and fit a new ignition amp and renew fuses #11 & #13 as if nothing else, it will eliminate those from the equation. Will also give you some peace of mind when using it but also make sure the fuel pump relay is secure in its socket.

Originally Posted by Moomoo

Could it be an essential , electric component overheating? Coil? Ignition switch?

Is that too simple?

Yes Andrew, i think it is too simple, too many other things wouldn't work either. The coil is highly unlikey (not impossible though) as they are about the most reliable coils i've ever come across, ignition switches do play up but usually only on start-up, not once running. The contacts and springs inside the starter switches (as Volvo call them) are vastly over-rated for the use they're put to so last an incredibly long time. I have had one fail on one car but it still always started, just didn't always do what it should once it had started though!

Also because of the design, mechanical wear is in fact going to increase the tension on the cnotacts inside rather than reduce it as on other cars. In short, other cars use a cam system in the switch that uses the cams to push the contacts together so wear will reduce the pressure/tension on the contacts. Volvo use cams to move the contacts apart so any wear will allow the contacts to become closer.

Also on the same subject, there are a variety of different switches used on the 7/9xx range so until the old one is removed (fairly easy, one plug, two screws and a piece of trim) the part number won't be known.

[jlawler]

I'll get a new ignition amp but I can use the spare to test as I won't see a new one this side of the new year.

I also have a spare coil but like you said it is unlikely to be that.

Thanks again and hope you get over your booster before Christmas day.

[Laird Scooby]

Originally Posted by jlawler

I'll get a new ignition amp but I can use the spare to test as I won't see a new one this side of the new year.

I also have a spare coil but like you said it is unlikely to be that.

Thanks again and hope you get over your booster before Christmas day.

You should be able to find fuses in a local motor factors (do you have Halfords over there?) or even Halfords but the spare ign amp would be a worthwhile test, even if the fault was just delayed you'd know you were on the right track. Usually when they go they tend to play up after a certain amount of time running, as they get closer to their final use, that time gets shorter so if the spare runs for longer then dies the spare isn't much better but it's still better. If it runs for the same amount of time, i'd suggest the fault is elsewhere (fuses, fuel pump relay etc) and if it's even shorter time, almost certainly the ign amp but the spare is worse.

Thanks, the booster was nowhere near as bad as the first two jabs for side effects (at least so far) so i'm hoping i'll be back to normal (whatever that may be! ) by tomorrow.

[jlawler]

I have ordered an:
1. Ignition Amp
2. Fuel Pump Relay
3. Ignition Relay.
I should have them next week.

I also had a second Crankcase position sensor (new) so I swapped that in to see if (just in case) the Volvo one was dodgy. No joy on that.

I'm suspicious that these won't fix the problem and am thinking it might be the EZK. This is because while all the known parts have been swapped out with new ones (CPS, Temp Sensor) or ones that worked on the donor car (ignition amp, fuel pump relay, ignition relay) the problem hasn't changed.

Its almost like a computer crash. It just stops and then if I just leave the ignition off for about 30-60 seconds (it feels like a long time with your hazard flasher on) it just starts up again with no problem. Sometimes it runs for an hour or more sometimes 10 minutes.

[Laird Scooby]

Originally Posted by jlawler

I have ordered an:
1. Ignition Amp
2. Fuel Pump Relay
3. Ignition Relay.
I should have them next week.

I also had a second Crankcase position sensor (new) so I swapped that in to see if (just in case) the Volvo one was dodgy. No joy on that.

I'm suspicious that these won't fix the problem and am thinking it might be the EZK. This is because while all the known parts have been swapped out with new ones (CPS, Temp Sensor) or ones that worked on the donor car (ignition amp, fuel pump relay, ignition relay) the problem hasn't changed.

Its almost like a computer crash. It just stops and then if I just leave the ignition off for about 30-60 seconds (it feels like a long time with your hazard flasher on) it just starts up again with no problem. Sometimes it runs for an hour or more sometimes 10 minutes.

Have you checked and cleaned the fuses yet?

Also what are you referringf to as the "ignition relay"?

[jlawler]

Hi,
Yes I cleaned the fuses when you mentioned them. The Fuel Pump one (#11) looked a little tarnished but was sound. I have some spares anyway so I swapped it. Again no change in behaviour.

What I'm referring to as the Ignition relay is what I think people call the Radio Suppression Relay (is that the correct name?). Mounted close to the ignition amp on wing above the battery.

J