spluttering on boost

[stevie69]

new problem.when i put my foot on the floor it starts spluttering at about 0.8bar of boost,but if i only give it about half throttle it boosts to about 1.1bar no problem.just took my lambda probe out for a look and its white.i assume iv got a fueling problem so where would i start??its been ricad and used to boost to 1.3 no prob but would drop pretty quick..

[AndysR]

Fuel pressure regulator would be a good start then possibly fuel pump and checking the power supply to it to make sure it's a healthy power supply.

[stevie69]

cheers.was told to look at the regulator but the little elbow on it looks ok and tis to dark to see where the white plastic pipe goes.what would i be looking for?thanks for the quick reply..

[AndysR]

Unfortunately that's where it becomes slightly more difficult. At the end of the fuel injector rail there is a valve, very simlar to a tyre valve, easily to spot as it has a blue valve cap fitted to it. You would need to remove the cap and attach a fuel pressure gauge you would then take it for a run. On road test ideally you will see a constant fuel pressure reading with only a slight fluxtuation as you accelerate hard as the pressure regulator regulates the fuel flow. If you see the pressure dropping under hard acceleration then you would be loosing pressure as a result of poor pressure. This could be either because of a failing fuel pump, poor power supply, a blockage in the fuel system to the injector rail probably fuel filter, or that the fuel pressure regulator is failing and not controlling the pressure correctly. Unfortunately due to the age of the car it is likely that any one of those could be the fault or all could be contributing factors. That said you can do far worse than replace the fuel pressure regulator with a new one for piece of mind if nothing else.

[JelT5]

Seems to be happening to mine now, just to add to its knackered gearbox and clutch lol plucked up enough courage to take it out for a short drive yesterday and getting exactly the same problem as stevie69 :( fitted a new walbro less than a year ago and checked the wiring, so mine must be the fp regulator too.
Thought it might be HT leads at first, but having read this thread, its deffo the reg.
Thanks for the info Andy.

[stevie69]

going to try a new fuel filter today as a start..

[stevie69]

fuel filter hasnt helped.anyone got a fuel pressure regulator to sell?does it have to be of a t5?

[Rnash2002]

When did it last have plugs changed?

[Alan M]

Using a gauge on the schrader valve at the fuel rail you should be able to check the rail pressure at idle and with slight revving by hand of the throttle. That way you should see if the regulator is doing a job if any. Failing regulators don't seem to be common with standard bosch units. I would suggest starting with the basics of Plugs, rotor, cap and leads after checking pressure at the rail. Make sure your plugs are gapped correctly also.

[stevie69]

plugs are about 3 years old.done the distributor cap and arm the other day.been to the scrappies there and got another regulator.its of a 2.5 non turbo but looks the same.are they?

[Rnash2002]

My money is on plugs or leads.

[Volvostorm]

Same here, I change my plugs about every 6 months!

[stevie69]

is it worth trying to clean them up a bit??

[Rnash2002]

is it worth trying to clean them up a bit??
You could do and make sure the gaps are correct.
Think you can get volvo turbo plugs for little over £20 on ebay.

[Volvostorm]

Think you can get volvo turbo plugs for little over £20 on ebay.

Yes, you can :) (well nearly)

http://cgi.ebay.co.uk/GENUINE-Volvo-Spark-Plugs-TURBO-850-V70-S70-C70-S60-T5-/290548036896?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item43a6033520

[hd9584]

Could be your maf failing. Mine did this after I fitted a brand new pattern part. Lasted 50 miles then boost kept holding back on full throttle and spluttering. Got a bosch one and problem solved. (Learnt a lesson as well don't buy **** pattern parts of ebay!!!)

[stevie69]

the list is getting longer..

[hd9584]

the list is getting longer..
Yeah that's how I felt, replaced everything to get rid of the problem. How I didn't set fire to it was an example of supreme self control..

[stevie69]

everyone that said plugs could be right.cleaned and gapped them and it seems to have sorted it..

[Volvostorm]

I would still get a new set, 3 years is a long time.

[stevie69]

ordered yesterday.thanks everyone..