Other than normal wear and tear, are there any detrimental effects or added harm done to the engine by going full throttle in 1st and/or 2nd gear, then shifting up well before redline (say 4k rpm on a 7k rpm engine)?

Would it, for example, cause more PCV valve activity, increase carbon deposits, or gum up the inside of the throttle body? Does fuel injection, electronic throttles, or forced induction compound or alleviate any issues?

Would it be better (but slower :c) to not accelerate at wide open throttle, or to taper off slowly instead of instantly releasing the loud pedal?

I don't think this falls under 'driving habit' questions as I'm asking what mechanical maladies the habit may cause.

  • Interesting question. We had an interesting debate about whether it should be closed or not. I argued your point about it being the effects of a driving habit. I don't see any close votes on it so I suppose we'll see some answers, hopefully. Have to say that I like the question. +1 Feb 26, 2016 at 1:43
  • Hmm, how would it be better if you shifted at redline, though? I'm not sure I understand the question. Feb 26, 2016 at 12:38
  • @IhavenoideawhatI'mdoing edited/added to question Feb 26, 2016 at 14:20
  • Is this a modern European/Japanese car or a relic of a bygone era?
    – Separatrix
    Feb 26, 2016 at 15:50
  • 2
    I don't know about wear and tear but if you're at WOT and looking for a shift point you'd want to be shifting in the power band. I don't know of any cars that make peak power at the redline. Slowly releasing the throttle wouldn't be beneficial in this situation. I'd also imagine at WOT carbon wouldn't have much time to settle on valves and unless your car has a lot of piston blow by it would be a non issue.
    – Ben
    Feb 26, 2016 at 21:14

1 Answer 1


Seeing as it's my question, I've kept it in the back of my mind for a while. Without any hard evidence to back it up, I've come to a general conclusion that makes sense to me.

Immediately releasing the gas and putting the clutch in, such that the engine would go from WOT under load to idle without load, could cause unburnt oil, which was vented into the intake chamber via the PCV valve under full throttle, to swirl around and find a nice resting place for itself in the intake plenum/manifold/throttle body. If done frequently, I suppose this could lead to a loss of power when going WOT again, as the extra oil deposits are drawing into the combustion chamber.

Slowly releasing the throttle would limit the PCV activity towards the end of the go-fast session, allowing more time for the oil to enter the chamber and burn up.

Again, total guess, no data to back it up. Just thinkin' out loud!

  • hmmmmm....interesting. I remember seeing your question and thinking about it. Now i want to think about it some more. Which I am doing right now. Mar 30, 2016 at 23:57
  • I don't think the oil deposits from the pcv would affect performance that much? Isn't the engine burning pcv gasses constantly anyway
    – method
    Mar 31, 2016 at 0:30
  • @method I agree, but if enough oil built up it could effectively delay the response the next time you go WOT as it burns off the excess oil. Mar 31, 2016 at 13:10

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