V70 engine occasional loss of power
 

My 1999 V70 2.5 petrol (140bhp) suffers loss of power under certain conditions. After starting from cold it runs fine but if I only travel a short distance (1 to 1.5 miles) and park it before the engine has reached full operating temperature, on restarting after 10-15 minutes it won't pick up properly and threatens to stall. The fuel filter has been replaced and the fuel pump relay. It seems to happen only if the normal warming up process is interrupted. I suspect there might be a faulty sensor but has anyone else had this experience?

Hi Malcolm,

I haven't had that experience myself.

Any warning lights on the dash (and does the engine fault light bulb come on when you first turn the ignition on)?

Did the problem start recently? Did it develop gradually or suddenly?

Does the temperature gauge move up as the engine warms up, and does it settle at 3 oclock when fully warmed up?

Did you replace the fuel filter and relay as part of trying to fix this problem, or for another reason?

Has anything else changed recently that seems to correspond to the start of this problem?

Does your car have a conventional throttle cable or is it fly-by-wire (electronic throttle module)?
Do you have a distributor cap and HT leads, or do you have an ignition pencil at each spark plug?

Do you have a fault code reader?

Steve

Hi Steve, no lights come up.

Hi Steve,

The engine fault light does come on with the ignition.

The problem first happened last September, when the car restarted after a short stop but cut out entirely after about 200 yards. I called out the RAC but by the time they arrived the car started normally again and ran without a problem. Fearing that it could happen again I took it to a local garage who changed the fuel filter (which appeared to be quite old and something was loose inside it) but could find nothing else. It was about three months before it happened again but this time I was able to keep the engine running and, as the engine temperature reached normal, the problem disappeared. So I contacted the Volvo specialist that normally services the car (Wrights of Attleborough, Norfolk) and they thought the fuel pump relay was the most likely culprit, so it was changed. The problem occured again a few days ago but I was able to keep it running as I now understand the circumstances when it is likely to happen. Again, the problem disappeared as the engine reached normal temperature.

The temperature gauge rises as the engine warms and then holds steady at 3 o'clock.

The car has a physical throttle cable and has a distributor cap and leads.

I don't have a fault code reader. Nothing else has changed that can explain it. As it is such a very intermittent faulty it never does it when taken to a garage!

Malcolm

Hi Malcolm,

Frustrating.

Just 5 ideas:

1.
Have you checked or replaced spark plugs, ignition wires and distributor cap and rotor?
Maybe when the engine warms up partly, but not fully, one of those components is on its limit.
Original Volvo ignition wires have the week and year of manufacture on them. They don't last forever.

2.
Sometimes the electrical connector block on the back (LHS) of the ignition lock becomes erratic. See if wiggling the key helps next time it happens.

3.
Wild guess, check the condition of your battery cables near the battery, positive and negative.

4.
When it next runs rough, after stopping the engine first, see which cylinders are NOT contributing to the rough running, by pulling the HT lead off the spark plug or the distributor cap, one at a time. Or do it while the engine is running but you might get a shock.

5.
When you turn the ignition on, before starting, you should just be able to hear the fuel pump whirring for a few seconds (near the spare tyre well).
If it doesn't whirr, and the car doesn't start, then that needs to be looked at.

Steve

Thanks for the suggestions, Steve. They give me something to go on.

Malcolm

Dodgy coolant temperature sensor?

+1 for this, if faulty it will give a false reading to the ecu even though the temp gauge works okay, as this fault only seems to occur when warming up it may be worth changing it, not expensive and fairly easy to do.