slightly rough idle. Revs drop when using washer etc

[griston64]

I have a very slightly rough idle. Only fluctuates by about 100 either way. However when I use the washers or electric windows the revs drop down to about 500 or slightly less.

Is this likely to be the alternator ? I think my noisy in tank pump is also stressing things as well. I only have the one in tank pump so its high pressure

Cheers

[Dirty Rooster]

I would first check the alternator charge at various revs, yes.

[griston64]

Originally Posted by Dirty Rooster

I would first check the alternator charge at various revs, yes.

I don't have anything to check it with so will need to take it in somewhere.

[Laird Scooby]

Depends how quickly that +/- 100rpm is fluctuating! It might be nothing to worry about or it might be a problem!

I'd suggest firstly cleaning the AICV and all associated PCV hoses/stubs and flame trap, even if you've cleaned them recently. Also check for air leaks and so on, think you know the score on that by now. That should make your idle more even, may need to do the throttle body as well. I'll come back to the washers causing the drop in a moment.

As for the electric windows, they put quite a load on the electrical system for some unknown reason and can cause the idle speed to drop by 1-200rpm - this has happened in every 7xx i've had and there's no reason to expect the 9xx to be any different. This is especially obvious at the end of their travel.
What does help is to open each windo as far as it will go, spray silicone lube into the rubber channel at the top corners, let it run down/soak in for a minute or two then run the window up and down a few times, finishing on the up. Usually what i do is open all 4, start spraying at the drivers window then walk round the car a door at a time, spraying the silicone lube in.
Once i've sprayed all 4, i start on the drivers window up/down a few times, same number of up/down on each door after in sequence. If there's only a slight improvement, i repeat the whole procedure, if there's a good improvement i call it good.
While i have the silicone spray in my grimy paw, with winter coming in a also open all the doors (including the tailgate/boot) and again in a sequence, spray all the rubber seals with a good coat of silicone, move on to the next one in order and once all are done, back to the first and with a clean, dry cloth (microfibre ones are good for this) wipe off the excess and any overspray. Don't polish it, just wipe the excess off.

That should prevent the door seals icing up and sticking over winter, finally a lube of all the hinges, latches and lock barrels, except the ignition unless that is particularly sticky/stiff.

Now the washers causing the idle speed to drop - is it accompanied by engine misfiring? If so, the culprit is almost certainly the non-return T-piece in the washer tubing above the distributor.
They are designed to leak when they fail so if it's on its way out, it is likely squirting the dizzy cap/leads with water!

https://www.ebay.co.uk/itm/Volvo-139...0/113310818821

For the cost, it's worth renewing as a matter of preventative maintenance and may well cure the problem too!

If you fancy upgrading the washer jets while you're at it, these are excellent :

https://www.ebay.co.uk/itm/x2-Windsc...0/173393881462

They give a fan/mist spray just above the parked position of the wiper blades, easy to fit, pull the rubber hoses off the old ones, use an 11mm box spanner or deep socket, line two of the flats in the socket/box spanner with where the tangs on the jet will be and push the socket over the jet body from inside the bonnet. You'll feel a little resistance then a click and the jet pops out of the bonnet!

Then pull out the old, drop in the new and connect the hose, click into place and enjoy!

Takes longer to type than to do!

[griston64]

Originally Posted by Laird Scooby

Depends how quickly that +/- 100rpm is fluctuating! It might be nothing to worry about or it might be a problem!

I'd suggest firstly cleaning the AICV and all associated PCV hoses/stubs and flame trap, even if you've cleaned them recently. Also check for air leaks and so on, think you know the score on that by now. That should make your idle more even, may need to do the throttle body as well. I'll come back to the washers causing the drop in a moment.

As for the electric windows, they put quite a load on the electrical system for some unknown reason and can cause the idle speed to drop by 1-200rpm - this has happened in every 7xx i've had and there's no reason to expect the 9xx to be any different. This is especially obvious at the end of their travel.
What does help is to open each windo as far as it will go, spray silicone lube into the rubber channel at the top corners, let it run down/soak in for a minute or two then run the window up and down a few times, finishing on the up. Usually what i do is open all 4, start spraying at the drivers window then walk round the car a door at a time, spraying the silicone lube in.
Once i've sprayed all 4, i start on the drivers window up/down a few times, same number of up/down on each door after in sequence. If there's only a slight improvement, i repeat the whole procedure, if there's a good improvement i call it good.
While i have the silicone spray in my grimy paw, with winter coming in a also open all the doors (including the tailgate/boot) and again in a sequence, spray all the rubber seals with a good coat of silicone, move on to the next one in order and once all are done, back to the first and with a clean, dry cloth (microfibre ones are good for this) wipe off the excess and any overspray. Don't polish it, just wipe the excess off.

That should prevent the door seals icing up and sticking over winter, finally a lube of all the hinges, latches and lock barrels, except the ignition unless that is particularly sticky/stiff.

Now the washers causing the idle speed to drop - is it accompanied by engine misfiring? If so, the culprit is almost certainly the non-return T-piece in the washer tubing above the distributor.
They are designed to leak when they fail so if it's on its way out, it is likely squirting the dizzy cap/leads with water!

https://www.ebay.co.uk/itm/Volvo-139...0/113310818821

For the cost, it's worth renewing as a matter of preventative maintenance and may well cure the problem too!

If you fancy upgrading the washer jets while you're at it, these are excellent :

https://www.ebay.co.uk/itm/x2-Windsc...0/173393881462

They give a fan/mist spray just above the parked position of the wiper blades, easy to fit, pull the rubber hoses off the old ones, use an 11mm box spanner or deep socket, line two of the flats in the socket/box spanner with where the tangs on the jet will be and push the socket over the jet body from inside the bonnet. You'll feel a little resistance then a click and the jet pops out of the bonnet!

Then pull out the old, drop in the new and connect the hose, click into place and enjoy!

Takes longer to type than to do!

No misfiring it just drops the revs. I will check the washer pipes though. Do you think it's not the alternator then ?

Cheers

[Laird Scooby]

Originally Posted by griston64

No misfiring it just drops the revs. I will check the washer pipes though. Do you think it's not the alternator then ?

Cheers

I'm not ruling the alternator out, the windows take a lot more juice than the washers (even with the wipers as well) but either way, the engine management is set up to cope with extra load on the engine such as windows, wipers, heating and so on so shouldn't make that much difference.

I'd check the obvious first before going into the less likely.

[griston64]

I also think mt petrol pump buzzing like a giant helicopter isn't helping either. It must be having some effect on the fuel getting through ?

Just waiting for it to warm up a bit before I tackle that b**tard of a job !

[Laird Scooby]

Originally Posted by griston64

I also think mt petrol pump buzzing like a giant helicopter isn't helping either. It must be having some effect on the fuel getting through ?

Just waiting for it to warm up a bit before I tackle that b**tard of a job !

Could be the pump is getting lazy or maybe you need a new fuel filter. Not sure where the filter is on the HP in-tank single pump models but on mine, it's with the main pressure pump under the passenger seat on the bottom of the floor.

On the bright side, at least removing the single pump from yours will be in the dry, even if not very warm!

Don't forget a new tank seal (about £11 from Volvo) when you do it, a bit of Vaseline helps the sender/pump unit slip in easily and a little on the threads on the tank help the locking ring to tighten as far as it needs to.

Experience has taught me you need to renew the tank seal if it's disturbed unless it's virtually new as it will leak afterwards otherwise. Given that it's almost the same job as removing the pump/sender unit, for the cost it's not worth faffing about!

[griston64]

I contacted local dealer and I think they are around £11. I'm going to be ordering my new timing belt etc so will add that to order

[LPTJoe]

Originally Posted by griston64

I don't have anything to check it with so will need to take it in somewhere.

Or buy a multimeter for £5 and have the comfort of owning one for future testing.... Seems like a no-brainer to me. The alternator should be running 14V or more with the engine running, test it by touching both battery terminals as the car runs with electronic accessories (Stereo/lights etc) on, plenty of vids on youtube to show you how.

RE fuel filters, on your car it should be in the cradle underneath the car just next to where the second fuel pump would be on earlier cars with the second fuel pump (Although IIRC your car's a later model so no second pump, just the filter there)

On a side note, small amounts of drift in idle speed is normal on these cars and if you're looking for a glass smooth idle like the ones you get with modern coilpack/hi tech ECU driven motors you're going to be looking for a long time

I'd recommend a good 'stage zero' tune up if the car's new to you...

Replace all filters including fuel and change the oil. Take off your separator box, fill it with brake cleaner, slosh it about, blast it out with even more brake cleaner, clean all of the associated pipework/nipples too, replace o ring at bottom of separator and re-assemble. Make sure dizzy/rotor/leads/plugs are good, replace if not. Clean and re-install ICV. Check CPS and replace if wiring looks iffy, replace the CTS and possibly lambda too with genuine Bosch parts if any doubts about them and possibly even if you have no doubts as a matter of preventative maintenance. Check timing/replace belt if due and flush/refil coolant with blue EG so as the CTS gets a reliable reading and stays clean. Final step is pull fuse number 1 for a minute to allow the ECU to reset to factory settings and get used to the changes you've made.

^That little lot should all be achievable for under £150-£200 (The cost of a decent service at a garage) and provided you don't have any esoteric wiring/relay/fuse faults should see your motor as good as new.

HTH.