C70 t5 2000 running issues
 

Anyone else had this running issue. Car starts and idles fine until up at operating temperature, when around town the revs fluctuate between 1500-2000, car smells rich whilst stationary, iv cleaned etm, and it didnt make a difference, car drives absolutely fine over 2000 rpm, and boosts well. Anyone know the cause?

Hi P505

How long has it been doing that?
Do you have an engine management light on?
Anything changed recently?
Any codes?

Steve

Hi mate iv only had it a week, got advised for engine running rough on mot in jan so most likely since then.
No engine light.
Been on vida with it and its not thrown anything unusual up.
Literally just changed the plugs and about to road test. It had NGK plugs which were dark brown almost rusty with the centre having scorch marks on. Replaced genuine volvo so will do a road test and report back

I'm amazed Vida hasn't shown something with a 500 rpm fluctuation.
Have you checked your fuel trims on Vida.
Have you done a throttle body sensor coherence/integrity check with Vida ?
have you checked *ALL* the vacuum and breather pipes for splits etc ?

Does it have a jerky ride at under 2000rpm? My -99 C70 T5 had those issues, and I scratched my head a long time before I got to it, it was the inlet manifold pressure sensor MAP. Disconnected it, problems gone, so I sourced a "new" one from the breakers.

I havent done fuel trims on vida yet
I did do the throttle body check though and it came back well within the tollerences
Iv not yet done the vac/breather lines, are there any prime culprits that need special attention?

You have got the exact symptoms iv got, anything over 2000 seems to be fine! I have disconnected the map and it made no difference, however plgged that back in and disconnected the round one next to it and it made one hell of an improvement however its not completely gone away. Still no check engine light etc. Was it the round one that played up on yours?

I started with cleaning the round one, made no difference, then the other one, also just a clean, no difference. I didn't think of disconnecting anything at this point to see if that helped, but once I did, it was obvious what was causing the jerky ride and revs all over the place.

So did you disconnect something?

MAF big round cylinder near the air box?
or
MAP (probably on the tube towards the ETM under the intake manifold)?

Steve

If you meant that for me, yes in the end I did disconnect the MAP and found that to be the fault.
There seems to be two sensors on the intake, the MAP sensor for pressure and further in towards the ETM another round one that looks like some sort of heat/flow sensor.