Engine cut out and Lambda sensor
 

In previous threads I had the prolonged diagnosis of a crank case position sensor problem followed by diagnosis of a leaking head gasket shortly thereafter.

So now the whole top end has been rebuilt and there is a new crank case position sensor and a new lambda sensor (as I gather the leaking coolent kills them). Both are OEM parts. The car has been running really well and I couldn't be happier.

Then just the other day the engine cut out. Wouldn't start but after waiting about a minute it ran again with no issues (luckily this was at the Supermarket car park). There was no spluttering just died so very much felt like an ignition problem.

Then today it did it again but the Lambda sensor came on first before the engine died and when I got it to restsart the Lambda sensor light stayed on. I pulled Fuse 1 and restarted it and the Lamda sensor light went out.

So any ideas on where I should start looking? I don't want this to happen in the middle of the motorway! I assume it's some ignition issue that is causing the engine to die but where to start and go about testing it?

I have a new crank case sensor and the old Lambda plus the control modules from a previous car.

BTW I've checked all the connections to the crank case sensor and the Lambda sensor while the engine was running (tug/wiggle test) and nothing. Lambda sensor hasnt' come loose either, its tight.

In hindsight I should have got the fault light record before pulling the fuse to reset.

First of all, that isn't a warning light for the Lambda sensor. :nah: It's the engine management light and could be any one of a number of faults to bring it on. Really you need to read the codes before resetting them by pulling fuse #1 with the engine off and keys in your pocket.

Gut feeling says it sounds like either the fuel pump relay or the RSR - Radio Suppression Relay - rather than anything else or perhaps the fuel pump relay has come loose in the fuse/electrical board behind the ashtray. Pushing it back downinto its socket will confirm that.

Also as the engine has been apart, check the earth straps, particularly the one between the head/distributor and bulkhead, also check the HT leads for security in the coil and dizzy cap and anything else electrical that was distrubed including the battery terminal connections.

Yes I realised it was a dumb thing to do almost as soon as I did it. A moment of panic.

I'm checking all the bits that would cause the that light to come on from the fault codes. I'm assuming this is something related to the work on replacing the head and reassembly. Something just isn't quite right or connected properly.

Earths look good but I'll go round with a ohmeter tomorrow on them.
One thing I did notice from the fault codes is that things like the ECT sensor can cause it, is that mounted on the head? The sensors/switches weren't removed when the head was reconditioned (at least I left them on when I dropped it in).

Just in case I'll pack the spare bits I have in the car so I hopefully won't be marooned somewhere.

I'd be surprised if it's the CTS/ECT as that usually causes running problems, not cutting out. Can cause starting problems in certain cases. It's on the head underneath the inlet manifold between tracts 2 and 3 and tells the ECU and EZK the engine temperature.

I'd definitely be looking at what was removed and refitted, also things nearby those in case it was disturbed as those things were removed.

Hi,

I have now had two cars doing exactly the same thing, it was a combination of three different things. To simplify I will use the regs of both cars and describe the issues and rectifications under each.

R839TCH B230FK M90 230K ish at the time
Maf sensor suspected-I stupidly bought one from euro car parts and put it on and the car ran much worse than it did before so I thought **** its a faulty MAF I will get them to send a replacement which they did. Car still ran awful so I put the original back on. Whilst waiting for euro to deliver me the replacement I noticed that one or two of the vacuum lines were a little perished, having a large stock of genuine vac hose I went through them all and cut new ones and fitted them, it made a huge difference but it wasnt perfect. I then took the throttle body and associated boost pipe off and found it was horrific! It was as though it had never ever been cleaned in the cars life! I noticed both holes for where the vacuum pipes attach were blocked solid with gunge. After a full clean and a lovely fresh genuine gasket she ran like a dream, never to cut out again! That car still comes back to me for a service, the lady I sold it too loves it and it has to be the biggest regret of mine selling that specific car, as high mileage as it was it was probably the nicest 940 I have ever driven. Getting side tracked here lets move on.

P571AYJ B230FT M90 128K
I replaced all the vac hoses as this car would not idle whatsoever! The ICV was rammed solid so I got a replacement one, checked the throttle body and this one was clean, however it still occasionally did the old cutting out routine for no reason whatsoever. This car had already recently had crank sensor, both coolant sensors and knock sensor. I had done several things like the PCV change and a full service however I had been meaning to do the fuel filter but I broke a spring so ended up playing with that and forgot about the filter. I then found some time to do it, i had the new copper washers too so we were onto a winner here. I ran the car right down so there was hardly any fuel left, put the filter on, primed it with the fuel pump, chucked a whole bottle of wynns in and its never cut out to this day since! Interestingly on examining this extremely rusty filter it had a date mark 10/96 on it so was the factory original which has been a big theme with this car! Even the dizzy cap and rotor arm were 1996 stamped, how it ran at all I will never know. It only ever went to a garage for an MOT and being a one owner car it only has 3 stamps in the book! PDI 1997 16 miles, service 1 2004 56000 miles, service 2 2013 104000 miles.

So long windedness over (sorry if iv bored you!)
1) check all the vac lines and the vac ports on the inside of the throttle body. If the vac lines show any sign of stiffness, perishing or if you wipe your finger over them and you get a black line of rubber on your fingers they need doing. The hose is readily available from Volvo sold by the meter and 2m will do the whole car.

2)check the ICV is clean and works properly. If its non functioning get a new one for it. Check the rubber pipes for it in good condition and are not split, the jubilee clips are all present and tight enough.

3) change the fuel filter with a genuine one. I suppose the theory of it would work a bit like a hoover, if its clogged fuel delivery will be lower or harder to achieve, talking to a mate about this he had running issues and I said change the fuel filter and it made a hell of a difference. Its even made my miles per gallon increase!

Another often overlooked thing with the earth straps is their general condition! If they are corroded they can play up. There is a blue earth cable on the back of the alternator as well to check security of. Another plug that could have been disturbed and easily overlooked is the MAF sensor plug.

Thanks for the advice.
I had changed practically all the vacuum hoses on this car when I got it. The only one I haven't done is the one that runs through the bulkhead on the drivers side. But I had never checked the connections to the inlet manifold.

The throttle body is actually very clean (it has 256k on it). The car (98 945 B230FT) had a full service history (for what it's worth) and one owner when I got it and I've always routinely serviced it. The only nipple that was blocked was the one running to the crank case breather hose and I suppose that's not a surprise considering the connection.

I had already found the source of one vacuum leak when I had the head off, it was on the heater control valve feed. https://www.volvoforums.org.uk/showt...=313712&page=8

I went over all the earth straps on the manifold and rocker cover and they are all good. The blue alternator strap could have been a bit tighter than it was so that is a possible source of the problem.

Anyway I took the opportunity to loosen/tighten the timing belt tensioner.
I'll see how it goes and hope nothing else turns up.

I forgot to say I changed the fuel filter when I got the car but that is now 80k in the past. It is due a new one.

Is the ICV the idle air control valve? I'll take a look at it.

There are a number of common faults but the first thing to do is diagnosis. Reading the codes out will help but I suspect it won't tell you much.

The first test is to use your ears in a quiet environment, so this may not always be possible. Turn the ignition on and listen for the pump whining during priming, Lifting the back seat can help. This gives an indication that the pump isn't working. 96 on models need left for about 10s before they will prime again.

The second test is when trying to start it, and it doesn't start within the usual time (about 1s). Check if the rpm needle is moving slightly (it won't move until the normal start time). This is triggered by the coil back EMF and give a good indication of sparks.

Common faults are
Faulty pump control relay
Faulty pump (some have 2 pumps, some 1)
Faulty ignition amp
Faulty crank sensor

These can all be intermittent and start after a cooling period, randomly or with a thump.

The injector supply relay (RSR) is also common, but not detectable with the above test, but has been covered by Dave already.