Idle Control Valve? ECU? Worse...?

[HuskMan]

I've got a problem that comes and goes and proves difficult to diagnose because it isn't there when you take it to a garage (don't you just love them problems).

When my foot is resting on the throttle (i.e. no pressure) the car lurches back and forth - quite violently - for about 10/20 seconds. First thought was an air leak but elbow has been changed, no obvious leaks and no response to WD40/hairspray test.

Even when moving at 30mph and 60 mph the car drops revs, then revs, kicks out dark smoke (blackblue) from the exhaust and sometime stalls - even doing 60mph cruising downhill on A38 towards Lickey.

Worst case was doing 10mph in traffic. Stalled repeatedly, kicked out loads of smoke. With a bit of revving and getting going the problem passes.

I stopped at the roadside and tested it idling. Started fine. Engine then revved to 2000rpm and dropped off and died.

I think I've got it down to a dirty idle control valve. Is this a job for a muppet like me to do? Is it easy to clean on an 850 or does it need a new one?

Any suggestions?

[HuskMan]

Heap of crap. So frustrated. Surprised I'm not in the Spotted! forum today as I sat on the M1 hard shoulder for half an hour tonight trying to work out why the car runs beautifully all day then collapses while doing 70mph. Just gives up. Smoke out the exhaust, no response to throttle depression, lurches forwards and then dies as I pull onto the hard shoulder.

I'm guessing a lot of money for this... I haven't had a month this year when this car hasn't broken down and needed garage attention. I bought it for its reliability :-(

[t5owner]

Looks like you bought the only volvo to be made at 15:30 on a friday afternoon i:e throw it together quick lads as its home time

Hope you get it sorted

Cheers

stuart

[volvotuning]

I've got a problem that comes and goes and proves difficult to diagnose because it isn't there when you take it to a garage (don't you just love them problems).

When my foot is resting on the throttle (i.e. no pressure) the car lurches back and forth - quite violently - for about 10/20 seconds. First thought was an air leak but elbow has been changed, no obvious leaks and no response to WD40/hairspray test.

Even when moving at 30mph and 60 mph the car drops revs, then revs, kicks out dark smoke (blackblue) from the exhaust and sometime stalls - even doing 60mph cruising downhill on A38 towards Lickey.

Worst case was doing 10mph in traffic. Stalled repeatedly, kicked out loads of smoke. With a bit of revving and getting going the problem passes.

I stopped at the roadside and tested it idling. Started fine. Engine then revved to 2000rpm and dropped off and died.

I think I've got it down to a dirty idle control valve. Is this a job for a muppet like me to do? Is it easy to clean on an 850 or does it need a new one?

Any suggestions?

Try disconnecting the MAF sensor and see what happens. If it idles ok, your MAF is naf!!

More importantly, what do the fault codes read?

Adam.

[HuskMan]

Sorry guys! What was I thinking. She's a beautiful machine and - like all good things - takes patience. I was tired from a long long day and the kids were driving me nuts.

Adam - no fault codes. No Lambda lights. I'll pull out the MAF though.

[HuskMan]

On idle I removed the MAF and the engine died. MAF not so naf unfortunately. What else could it be?

[volvotuning]

Try holding the revs at 2500 rpm while in neutral. If you can't hold the revs steady, you may have a leak at the inlet somewhere.

Are you sure none of the pipes have come off?

Adam.

[lance]

I would pop into DPA or VT mate asap

[HuskMan]

DPA too busy and can't see me for ages (Dave is on holiday). Getting to VT is a bit risky as it is an hour away.

All the pipes I know about are connected and it runs fine _most_ of the time and then just gives up. If it happened all the time I may have a better idea of what the problem is.

I'm taking lunch now and will go look at the old girl.

Adam - is VT open Saturday morning? If I got down there real early would I have a chance?

[volvotuning]

Not this Saturday I'm afraid.

Adam.

[HuskMan]

Right! I am back in from the cold and I think - after all this nonsense - that the mAF is stuffed.

Tried running the engine at 2500rpm and that was fine (trickier to do than you'd think from cold).

In desperation I unplugged the MAF sensor again and it carried on running. Plugged back in - fine. Unplugged again - fine. It did cut out after about a minute f running with the MAF unplugged.

Eventually the Lambda light came on (as you'd expect I suppose).

So, a MAF sensor it may be.

Adam - any cahnce of a Monday morning quick fix?

[volvotuning]

Please call if you want to book it in, but should be no problem.

Adam.

[watteee]

my MAF went a week ago,slightly different symptoms and at £300 was reluctant to take the chance,however i bit the bullet and it was the MAF,so happy again.

try tapping the MAF sensor with the handle of a screwdriver when the car is running ok and if the idle gets erratic which mine did then theres your answer,it worked for me.

unplugging the MAF will turn the ecu light on your dash and maybe other codes might come up too,after unplugging mine i had 4 fault codes showing.hope it works out ok for you as i was for giving up but now im happy.

[HuskMan]

Right, MAF it is.

Does anyone know about this bloke in Nottingham selling MAF sensors on ebay? See Item number: 4569586646

At £120 it really is tempting...

[Vikingxl]

Take it to VT i had a problem with mine that could have been the MAF so they fitted a new one it didnt make any difference so they took it out no charge.If it isnt the MAF then at least you havent lost anything if you buy one for £120 and still have the problem you arent going to be too happy.Plus while you are there if it is something else they should be able to sort it for you.

[HuskMan]

Rich T5 (biscuit)

Fair comment mate. I've spent a load on this 850 bucket since I've had it and every month it has been parked on one hard shoulder or another across the country. Sometimes with the family in tow wondering why we keep the red brick and why we don't cut our losses.

I just feel like being on the winning side for a while and getting a bargain.

VT are superb, top blokes and great job but the MAF will be 300 quid plus and I just can't afford that at the moment.

If the damn car didn't make me smile so much when she does run well it would have been curtains a long time ago.

[Vikingxl]

Good luck with it mate i know how you feel I've decided to loose track of how much i've spent now.You cant help but smile when its running right and yet another sports car is disapearing in the mirrors!

[TangoDeltaSierra3]

Sorry to hear your having more trouble, i would go with the ebay one, does he have any feedback ?

[Vikingxl]

Any members near you that might lend you theirs for an hour or so.Dont know if that is possible to do but might be worth a go.

[HuskMan]

Tango DC

Good feedback and he is local so I'll give him/her a PM tomorrow.

Glad to hear that you've got your motor all sorted now - must leave you grinning form cheek to cheek. After I left you at VT last week my R was just awesome. All weekend in Wales she was everything you'd hope for - until this new problem cropped up.

Sitting on the M1 hard shoulder on Thursday was just a nightmare.

I'm sure that if I can solve this last problem then the car will be great but I've said that the last couple of months...