2001 C70 - Hesitancy while driving
 

My 2001 C70 with the B2544T engine does not feel like it's performing well. When you start driving it at first, it labours under acceleration and requires you to take your foot off the throttle and put it back on to get it going. Overall it feels hesitant when driving and not like it's delivering its full power. I thought it might be the usual ETM to blame, but it does not have any of the other symptoms such as poor idling. I have plugged it into a diagnostic reader and there are no fault codes.

Anyone had any similar issues?

It could be just about anything, mine had the same symptoms and no codes, Volvo diagnosed it as a faulty ECU, but after disconnecting and reconnecting it a few times it now seems to work as should again.

Other possibilities are vacuum/air leaks, MAF, earth/battery problems.

Sounds like a vac leak to me. Well worth going through them all and replacing them - especially when they're all going to be getting on a bit age wise and the replacement is silly cheap.

Pull the MAF out, go around, if your symptoms are gone, then either way the maf or vacuum leaks... U can get new mafs on ebay for £70ish. But you should go around w a water spray bottle 1st to see the vacuum lines...

Edit... Only, and i mean ONLY buy BOSCH original (new, official replacement) maf sensors... Dont bet on cheap off brand ones...

Check the airbox, the filter might be dirty.
Ecu reset if nothing else?
Doesnt seems like a throttle body problem, it seems like the ecu gets mixed data or processes the data badly

Thanks to everybody who responded. I will look into all that has been suggested and hopefully will get somewhere.

IMHO as above - change the air filter AND the fuel filter....if it is being starved of fuel it is unlikely to show up on any fault code reader or even ViDA/DICE for that matter as the mix is unlikely to trigger the lambda codes, as the exhaust manifold gasses will be within the limits.
Having said that it is worth cleaning the both the electronic throttle body and the air flow sensor, but do make sure you use a dedicated throttle body and air sensor cleaners - using the wrong cleaner on an air flow sensor will damage it and then require replacement - similarly the ETM...many pennies!!!

It is also worth checking the integrity of the vacuum line from the air filter box to the right hand end of the manifold: both of the rubber/silicone sleeves have a habit of perishing over time which reduces the amount of fuel supplied to the injectors so you end up with the car running lean ie struggling. Check the air pipe from the filter box to the throttle electronic body, these can split and allow too much air to enter the inlet manifold as the splits come after the airflow sensor. Check also the other tubes connected to the air filter box as these too can become damaged or detached and seriously impair performance.

When all is refurbished/repaired run reset cycles (there is plenty of information available if you search for "re-learn" Volvo settings or similar) so that system"re-learns" the optimum settings. :GEEK: