Important! : VTS lumpy, underpowered, doesn't pick up through revs, bad idle - suggestions please!

  1. #1
    I apologise in advance for the long read

    This has been an ongoing issue for around a month now. The saxo started idling high and idling at different RPM (doesn't stick to a certain idle level). If this was the only issue I'd think Idle control valve.. but it isn't. It is also running very lumpy. The exhaust note has also completely changed, went from raspy as f*ck and free revving to a lot more groany and just doesn't pick up through the revs at all.

    What has been changed: Fuel filter, spark plugs, coilpack is only one year old, lambda sensor is only one year old

    I have taken it to an experienced garage that I use a lot and they performed a diagnostics test on it. I cannot remember the specific results but some levels showed up high on the diagnostics and these were reset. Idle was also reset. The car was perfect for 2 weeks. Then out of the blue it just switched again to being how it was. Took it back to the garage, back on the diagnostics, this time the lambda reading was incorrect so they reset it. Again, car was perfect for just over 2 weeks.

    Was driving along the other day, stopped at some lights and it begins to idle all over the place and goes back to square one; lumpy, doesn't pick up at all, feels like it's lost half of its power, exhaust doesn't pop or sound free flowing like normal... just completely changes the characteristics of the car and it sounds and feels completely different.

    I am taking it back to the garage in a few days and they are going to dig a lot deeper this time. I just wanted to ask here first to maybe help point them in the right direction to save some time, and money! They are obviously doing something right as each time it seems to run perfect for a couple of weeks... It's like its then resetting itself to how it was.. and it just will not correct itself

    Sorry for the long read, it's quite difficult to explain.

    Thanks in advance for any replies.
  2. #2
    I'd change the Lambda sensor again. What type did you put in when you last replaced it?
  3. #3
    Quote:
    Originally Posted by Mickswan View Post
    I'd change the Lambda sensor again. What type did you put in when you last replaced it?
    It's just quite an expensive thing to try if the current one isn't causing the issue. I will suggest it to them though. Not sure on the type as the garage did the last one. It wasn't a cheap one though as I remember the part alone was over £100
  4. #4
    £100 is quotes expensive. You know Anyone local you could do a swap with to test?
  5. #5
    Nah I don't unfortunately. It could be the lambda, I just think it's deeper/more involved than that if I'm honest.
  6. #6
    If its still happening I'm going with coolant sensors man, iv got spare you can have for £5 each
  7. #7
    Map sensor or tps sensor.
  8. #8
    The problem with sensors is, they aren't cheap so I don't want to buy like all 6 sensors and spend over £200 if it turns out to be something else. What makes you think it could be the ones you have suggested out of interest?
  9. #9
    The tps will affect the idling & produce sticky revs,the map sensor will cause bogging down.
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