S70 t5 misfire under acceleration

[JayH]

Hi guys own a 1998 s70 t5 volvo. When i first bought it three months ago on some days it used to run worse and had a very slight not noticeable misfire. Recently its gotten much worse when i press the pedal fully and goes to 3500rpm it misfires if driven normally its fine. I've had spark plugs done but not cured it. Then handed it to a specialist on his diagnostics said its rear 02 sensor. But without doing anything fault went but after hitting boost twice its back again. What would you suggest i try? Specialist is saying to put in a genuine volvo 02 sensor but don't wanna start throwing money at the car if it won't fix it

[Rnash2002]

Was going to say plugs but you have changed them, has it been mapped? also do you know what boost its running with a gauge or something?

[Shinsplintz 101]

I'd double check the ignition system again, leads & dizzy (if pre me 7) & the coil. Wouldn't have thought the o2 sensor would give you a misfire, possible rough running but if it's throwing a code then change it out.

[stribo]

I'm running my C70 with the rear lambda disconnected, with no problems.

[JayH]

Was going to say plugs but you have changed them, has it been mapped? also do you know what boost its running with a gauge or something?

Had a ricca remap three years ago before i bought it. Dont know what boost but is running 311bhp

[t5 pete]

Certainly sounds like a break down of the ignition system personally ide go through the entire system at the age these cars are they will need doing

Also with regards to the 311 bhp unless you have some serious mods I doubt it very much not wanting to break your balls but people have maps done like Rica 310 ect and think they have instantly 310 bhp but more like 270-280 some even less

[Redbrick]

As above a good stage 0 should fix it.

Coil, leads, plugs, dizzy arm and cap (if not ME7)

buycarparts.co.uk have keenly priced genuine Bosch parts, I wouldn't go cheap aftermarket.

Leads made by Bougicord from Partsforvolvos. Actually have Volvo stamped on them.

Genuine Volvo plugs.

[960kg]

Hi guys own a 1998 s70 t5 volvo. I've had spark plugs done but not cured it.

I would gap your Genuine Volvo Spark Plugs at .7mm if you have a remap...

[JayH]

Was the rotor arm And leads. Running smooth as anything now.

[Redbrick]

I would gap your Genuine Volvo Spark Plugs at .7mm if you have a remap...

378 bhp with standard out of the packet gap. Needs good map and A1 ignition system.

[Saaamon]

Was the rotor arm And leads. Running smooth as anything now.

Glad you've got it sorted, these parts and others will wear out quicker even with just a remap.