1998 945 2.3LPT lambda woes

[mylittletony]

Hi everyone,

firstly, I hope you all had good christmases and new years? Haven't been on here in a while due to motorbike fixing and longstanding good behaviour from the volvo.... until now!

3 months ago when I bought my 940 (1998 LPT version) some sort of rusty, flaky mounting boss fell out of the downpipe while applying some revs to check for smoke.

This didn't affect the drive in the slightest and even after turning up the boost from 4psi to 10psi there were no ill effects. I've been meaning to patch the resultant hole for some time, although it's quite amusing as is 8-)

However, driving home the other day, it developed a serious misfire under load (coughing and spluttering, lack of power). Mr RAC said it was probably water in the distributor cap - it wasn't. He then said the hole in the exhaust would be fooling the lambda sensor and I should sort it out. I managed to drive gently home (100 miles!!)

I got underneath it and found a distinct lack of lambda sensor, no wires and nothing tucked away...



Under the bonnet, there's this disconnected bit of wiring:



everything else across the bulkhead is connected and present:



excuse the purple vacuum hose, moment of madness/clarity (haven't decided which yet) :P

So, I'm planning to buy one and a mounting boss. My questions are whether that is the correct bit of wiring to plug it in, why someone would totally remove it in the first place and what thread size the sensors are (if anyone knows of the top of their head)

I'm also thinking new leads, distributor cap and rotor (had new plugs and a service 3 months ago)

all help greatly appreciated!!

Regards,

Tony

[Steve940estate]

Turbo cars (in the UK at least) have the lambda sensor right up near the turbo. The hole in the downpipe is just an extra boss that isn't used, it just has a blanking plug in it.
The hole shouldn't really have been affecting the sensor, I would be more worried about the raised boost. Have you been running the car on high octane fuel ?
I would take the plugs out and check for anything strange, check the coolant and oil levels in case the head gasket has cried enough.

It could be just a simple ignition or plug fault, fingers crossed eh !

Looking at the picture the brown plug on the firewall is the lambda sensor connector. Not sure about the one by the turret. Could be a spare for the alarm or EGR valve, your cars a bit newer than mine so I'm not sure.

[mylittletony]

Originally Posted by Steve940estate

Turbo cars (in the UK at least) have the lambda sensor right up near the turbo. The hole in the downpipe is just an extra boss that isn't used, it just has a blanking plug in it.
The hole shouldn't really have been affecting the sensor, I would be more worried about the raised boost. Have you been running the car on high octane fuel ?
I would take the plugs out and check for anything strange, check the coolant and oil levels in case the head gasket has cried enough.

It could be just a simple ignition or plug fault, fingers crossed eh !

Looking at the picture the brown plug on the firewall is the lambda sensor connector. Not sure about the one by the turret. Could be a spare for the alarm or EGR valve, your cars a bit newer than mine so I'm not sure.

Cheers Steve, will check the downpipe further up. The boss that fell out during the inspection had not had anything attached for a LONG time, which is why I was dubious.

I have been running it on super, until the last run funnily enough... I put a tank of normal in because I knew I'd be cruising along (had the other half in the passenger seat ) Definitely not making that mistake again.

I really hope it's not the HG, it runs really well until you press a bit too hard on the throttle then it throws it's toys out...

I should also have mentioned that the ECU warning light has been on for some time, although it's been running so well that I haven't investigated further.

Would old distributor parts cause this kind of problem?

thanks again

[Steve940estate]

Hopefully it isn't the headgasket, just something to kep an eye on.
Old leads, distributor caps and rotor arms will cause problems, if you need to change them get decent ones if you can afford them. The plugs could still be a problem, even new ones can fail plus you will spot anything else going on if you have a look at them.
My car used to leak oil into the distributor cap quite a bit and that can cause a few odd moments.

[mylittletony]

ok, just got home and had a quick check:

1. the lambda sensor is in the downpipe after the turbo - bit embarrassing...
2. oil level fine and no mayo stuff on the filler cap
3. coolant level low and clear, although I haven't checked it since I bought it (already slapped my wrists for it) I topped up to max with antifreeze and will check again having made a short run I need to make this evening (once cool...)

Will check the plugs once I get some daylight, new leads etc will be purchased later.

Many thanks again Steve!

[Steve940estate]

Avoid Halfords ones if you get some. I can say from experience they are rubbish as the ends fall off, not sure about Bosch ones they also sell.
Hope it isn't anything too bad.

[mylittletony]

well, I've just returned from my "run"... Car wouldn't fire on all 4, so had to leave it.

So I'm now faced with a car that runs on 2, maybe 3, cylinders! I'm about to pop out and check the plugs, can't say I'm hopeful though.

HG seems more and more likely, @r$€.

[mylittletony]

Right, went to check the plugs and they're all the same, although quite black...

Starting closest to the fan and working towards the bulkhead:








Apologies for the poor phone pics, having seen them on screen they're really sooted up - hmmm

Still running rough though, I'd say 3 cylinders as it just keeps itself going.

Unfortunately I don't have a compression tester, do people think this is a blown gasket even though it's not smoking a great deal or an ignition problem??

thanks again for all the help so far.

Tony

[Steve940estate]

The fact that they are very black suggests it's running rich. That might be why the light is on.
This might be down to the hole in the exhaust so it could be worth blocking the hole off. Use an exhaust clamp and a bit of tin can or similar as a tempoary fix. Might be worth cleaning the plugs or even putting the old ones back in.
It might then be worth trying to clear whatever fault code you have thats made the light come on. I can't help as later cars are different but early ones would clear if you disconnected the battery for 20 mins. Have a look throught the frequently asked questions sections for more info about it.
If you disconnect the battery you will loose the radio code and possible mess the alarm up if there is one fitted.

[volvoz2000]

back to basics people!..... You need to find out which cylinder is causing the problem:

Start it up and then pull 1 lead off at a time until you find the lead that makes no difference to the engine note. Once discovered you need to take the plug out and wedge it somewhere there is a good earth (with the leasd reattached) and crank to see if you are getting a spark. If no spark then use a different plug to prove whether the plug or lead/cap is at fault. IMHO the hole in the exhaust is irrelevant, forget about that. If spark is good then you have an ECU/injector/resistor pack/relay issue. but we won't go into that until we know the situation with your ignition system