Hello!

I’ve been having this issue for quite some time now and typed in many forums and also contacted several types of mechanics but so far no one knows a possible solution.

My V70 T5 can sometimes have a sudden drop in idle, mostly when I do a quick stop at an intersection. The idle can drop to 3-400 RPM before getting stable at 6-700 again. This happens rarely but can become more frequent a short period of time, mostly after a more aggressive driving.

Also, the car can become a bit jerky in the acceleration. If I do a big sudden acceleration (not pedal to the metal) but kind of, the car can be a little bit jerky. Not a lot but you can really feel it in the entire car, this mainly happens if I accelerate uphill. The steeper the hill, the more of the jerk you can feel.

There are no fault codes on the car that is connected with any of these issues except maybe one and that is "faulty software" but the car has been tuned and is said to display this code if that is the case.

I’ve done ALOT to try solving this but nothing has helped…I’m out of ideas. My last resort is that my turbo is going bad, but I can’t find a thread that has those symptoms when a turbo is going bad, and it’s expensive to change on a hunch.

What I’ve done so far:

1: Tested for vacuum leakage with both smoke and LPG, no result.
2: Replaced the fuel pump and tank fitting.
3: Replaced the fuel filter.
4: Replaced the air filter.
5: Replaced the air mass sensor incl. housing.
6: Replaced all ignition coils.
7: Replaced all spark plugs.
8: Replaced all fuel injection valves.
9: Replaced the fuel pressure sensor.
10: Replaced solenoid valve (turbo).
11: Replaced evap valve.
12: Replaced the entire crankcase ventilation.
13: Replaced the manifold-intake-gasket.
14: Replaced the throttle body.
15: Been reading out live data on the oxygen sensors (TRIMS), misfires, fuel pressure etc but can't see anything abnormal with it.

There is one thing that i still need to fix with the car but i have no idea if this may cause this. My fuel tank filling neck is leaking from the small metal pipe if i fill the gas tank to the top (when the gas pump clicks). It starts dripping for a little bit before it stops. I'm waiting for parts to replace this but there is no delivery date yet.

To see the part, visit this link: Volvo Fuel Tank Filler Neck - Genuine Volvo 8624704 | FCP Euro

What else is there to replace?

/Toby

 

Any luck resolving this?

 

Hi,

No I have not unfortunately.

Though the jerkiness when accelerating has been resolved and was do to a bad clutch, mostly the spring.

The idle problem still remains and so far my best guess is that it might be the VVT on either the exhaust or intake that might cause the issue. Other than that I’m still on square one and no one has been close on solving it. Mostly I don’t even get replies.

 

I've a 2006 that's seeing a drop into the 15 psi range for fuel pressure when accelerating uphill or turning.

Replaced the fuel pump twice, the fuel filter, the PEM, spark plugs, and fuel pressure sensor.

On the previous fuel pump had it die several times but would come back after priming the fuel pump. Would also drop in pressure and accelerate jerkily on level straights from time to time.

At a loss for what to try next.

 

I would make sure that the pump actually works by reading the voltage and that it is oriented in the tank correctly, they need to be mounted in a specific orientation for both the pump and the secondary sensor. Also I would recommend to buy common and well respected brands if you haven’t already if your last one was in such bad condition that it killed the car completely. (If the pump was the reason) Check as well for damaged cables, might be a short to ground happening when the car moves suddenly etc, the relay etc.

make sure that the filter is mounted in the correct direction. (it can happen even to the best of us :P)

the third step would be to check your fuel injectors. They might be clogged or just not working as they should. You can remove the entire rail and try to start the car and look at their spread of fuel.

if you haven’t you need to check for fault codes. Checking fault codes is more or less always the number 1 thing to do with a car, also with a good reader. Cheap ones may not find all the codes or read them correctly. I’ve recently bought Vida Dice to do this.

 

Turns out my problem was a cracked fuel level sending unit.