Problem with 940 stalling/cutting out
 

Hi,

Currently Im changing the fuel filter on my 940 R reg estate and the exhaust back box (hole in it). Im also changing the ht leads when they arrive, but I have had a continuous problem with the car engine stalling just after a few seconds of starting it. Always happens at the start of reversing it off the drive. It cuts out mostly in reverse, its an automatic. The idle tails off slowly and it shudders, then you have to start it again and just put some revs on, then it runs fine going to work.

The other problem is when going uphill after its been run for a while, the red warning emissions light flickers on the dash when pressing the revs like its a misfire. When you dont press the revs its ok. Seems to be on an incline only.

the car runs ok as long as you dont pressure it too much. On the motorway its perfect.
Should I check for vacuum leaks?? Is it the coils??
The car is used as a workhorse so I really dont want to lose it.

Steering rack was also an advisory on last mot, how much are these, or can it be repaired.

Thanks, also need to get a new fuel sender unit as this one keeps showing full when its not.

I think you may have unwittingly diagnosed the problem! It sounds very much like a bad earth on the fuel tank sender/pump unit. I'd make a guess it cuts out most when the gauge is over-optimistic?

Also when thre's no more than 1/4 tank, i'd suggest adding 2L of meths to the tank to remove any condensation you may have in there - the other symptoms concur with this as well.

Those are non-temperature related problems as th Lambda sensor doesn't function until it's warm. However something is causing the engine management light to come on under load, could well be the Lambda sensor or possibly the MAF. Have you also checked the air filter for cleanliness?

As for the steering rack, what exactly was the advisory?

Yes something to go on. I keep running it low on petrol, really never fill it up, yes possibly new sender unit/bad earth. Air filter is new, maf was replaced before I got it last year. Its the emissions light that is flickering on when going uphill. Im not sure about putting meths in the tank, but will fill it up, maybe some redex could go in???

A few points - lift the cubby hole cover panel from the floor behind the left hand rear wheel arch - you should see the cable that supplies the tank unit which is the pump and sender. There will be a black wire coming from it, follow that to where it earths, i can't remember exactly where it goes just now but it's not far.
Remove that bolt/screw, clean the connector with a wire brush and/or emery cloth, clean where it attaches and refit it, making sure it's tight.

Next, it's not an emissions light, it's the engine management light and that suggests you have multiple misfires because it's getting poor fuel to the engine.
As the fuel pick-up/pump/sender unit is at the back of the tank, going uphill will make the problem worse, allowing more water/condensation to actually sit round the pick-up point. Water fill find the lowest point of the tank as it's heavier than petrol and will not mix with it. Adding meths allows the water to emulsify with the petrol so it can be burned off. You only need about 2L of meths in a maximum of 4 gallons of petrol.

Filling it up won't get rid of the problem if it is condensation, just make the symptoms worse. Once you've got rid of the problem, then add the Redex or other injector/fuel system cleaner to the tank.

I thought it was an emissions light! Mine is a lambda warning, it generally only works at idle and the ECU tries to cycle the misture to hit the O2 sensor cross over. If it can't get both in a certain time it lights the light.

Its not a check engine light (in my case).

I thought therefore that the light should not come on under load, unless its detecting a weak mixture (which I have no idea if it does or not). Could it be the throttle closed switch is stuck on?

Still if there is resistance in the pump circuit the fuel pressure maybe low. You could also check the pump voltage in the cubby hole while it is running.

thankyou for that, ive changed the fuel filter and I am going to do what you suggest. I do admit I dont even fill it halfway. Will let you know how it goes tomorrow.

Sorry for the forgotten update. The meths worked a treat.
But now its starting getting cold in the mornings again, the idle cuts out when after starting the engine, have to now wait till it gets warmish before setting off or it stalls on the drive.

New idle valve??

Glad the meths worked, had a feeling it would from your fault description. Might be worth giving it another dose, i've had that happen in the past where the condensation has built until it's giving a problem for a long time before it's noticed properly and then it takes two goes to shift it all.

That said, i'd also give your EICV/AICV (Electronic or Air Idle Control Valve - both terms can apply but generally AICV is the "Volvo recognised" name) a good clean with Carb and Air Intake Cleaner. Generally in an aerosol, remove the pipes/hoses going to the EICV (engine cold and off) and give it a really good spray in the direction of airflow. Let it soak for a few minutes then give it another squirt - not so long and intense this time.

Refit the hoses to the valve and start the engine, giving it a little throttle to overcome the fumes from the cleaner spray. Give it a couple of gentle revs (it's a cold engine remember, don't rev the guts off it!) to help clear the valve then, leave the engine idling, remove the hose from the air filter side of the EICV and spray some more cleaner through it - be prepared to grab the throttle and open it to keep the engine from dying if necessary, at least it's within inches of the valve so shouldn't need gymnastics!

After doing that, it's also worth cleaning the PCV system, especially the stub on the inlet manifold which often blocks - there are plenty of posts/threads on this, if you can't find one fairly easily, i'll explain it in a bit more depth here.

https://www.ebay.co.uk/itm/WYNNS-AIR...S/291313479578

https://i.ebayimg.com/images/g/FpwAA...NJB/s-l400.jpg

That's the sort of air intake cleaner i mean, should be able to find it in your local motor factors or something very similar, Toolstation do one at a nice price too :

https://www.toolstation.com/shop/Aut...Cleaner/p30713

Might also be worth checking your air filter while you're about it, there'a couple of deals on fleabay at the moment where you buy one for £4.99 delivered and get another free, as long as you order 2 in the first place.

I found that just carb spray used to clean all the lube off the IACV, and it would dry out and stick, so I dropped a few drips off engine oil into the moving parts of it (the valve has to be out of the car to do this) to relube it.

Can't say i've ever had that problem using carb cleaner to be honest - brake cleaner as a substitute carb cleaner, yes but not carb cleaner.

However i think i'd clean out that engine oil and spray some silicone lube into the valve instead - less likely to attract dust and dirt and won't turn to a gunny residue like engine oil will. It can also be done without removing the valve from the car.

I suppose i should have a look at my EICV/AICV as well, it's 2 years since i last cleaned it and i have an MoT coming soon. That said i'm not experiencing any problems in that area but prevention is better than cure! ;) :D