Engine: T5: Surging acceleration / vacuum advice.

[gswede]

Holy thread revival I know..

But, I have the excact same issue with my 97 855R.
Have been reading hundreds of volvo turbo hesitation/surge threads. None with conclusive answers.

Was the issue resolved in this case?

[Thanatos]

I can say that when mine did it it was a spark plug issue and after changing the plugs after 3k miles it cured it Volvo plugs were used on both occasions.

[Green440wedge]

I have been recently writing resolving the same problem on another thread - I would like to know if you all resolved your problem?

I have replaced:

Vacuum hoses to MAF
1 way valves x 2
Vacuum hoses to TCV (except 1 in good order)
TCV
PCV service - new catch tank
Spark plugs x 5
Coils x 5
Air & petrol filters

It now runs generally very well, except that it still randomly has a hesitation on hard acceleration, but not always, when the pedal is hard down. It no longer over-boosts, but when lifting off the gas from hard acceleration the engine tends to "thud", I don't know what that is, the turbo, engine mountings, who knows?

I have had the ECU codes read 200 miles ago - an ECU software and clock fault came up along with a throttle body no signal fault, then the codes were wiped, on reading the ECU 50 miles ago no codes were present. It has a yellow sticker on the throttle body so presumably an updated one.

Torque occasionally shows "no data" for vacuum/turbo whilst the other gauges are working, does anyone know where the sensor is for this?

Experienced comments would be appreciated. The car is running 85% that it was, I just need to iron out things a bit more. It has done 105K miles.

[Green440wedge]

PS forgot to mention mine is V70 Phase II T5 2.3, year 2000, 250bhp.

[Green440wedge]

Cleaned the MAF with brake cleaner, no more flat spots.........

[burkey7]

I have just bought a c70 t5 and it is doing this same issue. Pulls fine up to about 3k and then sort of stops and starts pulling but then seems to pull fine again after 5k.