The following applies mainly when accelerating from zero speed at 1st gear in RPM below 2500. Above that RPM range, there is no problem (then acceleration is assisted by turbo-compressor).

  • When engine is cold and I start the car, it is able to accelerate normally.

  • When engine has normal working temperature and I stop the car (e.g. at lights), then

    • if I accelerate after some 10 seconds, engine accelerates normally – no issue.
    • if I accelerate after 1-5 seconds, engine is very lazy: even with accelerator on the floor, acceleration is 3-4 times slower than normally. RPM increase very slowly like if the car was ignoring accelerator pedal.
  • OBD-II engine diagnostics shows zero errors.

  • This issue is new. Before the engine was accelerating normally under any conditions.

Any ideas what can be the issue?

This can create pretty hazardous situations because if the driver relies on usual acceleration but instead the car only unexpectedly slowly rolls into the intersection, there is a chance of collision.

Details: Opel Zafira B (2009) • EcoFlex Turbo 1.6 bi-fuel (CNG + Petrol), 150 hp • manual 6-speed

  • How is the exhaust? is it working properly? please check for any blockages, also the intake and fuel filter.
    – Shobin P
    Aug 14, 2015 at 12:58
  • @Anarach – A good idea, I'll check. Do you think that any problem with them could be of conditional character? (I.e. leading to issue only short time after stopping.)
    – miroxlav
    Aug 14, 2015 at 13:02
  • Yes,since when you stop or halt for a short moment there isnt enough exhaust coming out or enough air in intake for engine to breath in case of a blockage, but when you accelerate everything will be fine.
    – Shobin P
    Aug 14, 2015 at 13:04
  • I am not suggesting that the above point are the cause but , I had sort of a similar issue and it turned out to be a clogged exhaust. so its not bad to give it a shot. Although your exact timings of issues are very suspicious to me .
    – Shobin P
    Aug 14, 2015 at 13:06
  • I see. But is there some explanation how it is possible that after 10 seconds at the same RPM, everything works normally? I'd expect that any blockage would be in effect even after some time.
    – miroxlav
    Aug 14, 2015 at 13:10


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