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As with any car, you'll want to be a little gentle right off the bat when driving a cold car. Not granny driving, but not hooligan either - to let the engine warm up at least to some degree.

My car in particular, an Audi A4 2011 model 2 litre diesel, states in the owners manual that you'll want to avoid full throttle application and redline while the coolant temperature needle is at the coldest.

When I apply full throttle, there's a few factors I assume come into play that I'm curious about. Mainly, the engine produces torque from the combustion of diesel. With stock engine mapping on my car, that's around 290 Nm of torque in the rev range 1500-2500 u/min.

I've had my car stage-1 tuned, so it reaches 290 Nm at 1200 u/min, and I figure that the car can also produce 290 Nm with way less throttle application than with the original mapping.

So how does this work out and how does it affect the engine? Consider the two scenarios:

  • Original mapping, 290 Nm @ 100% throttle, undesired when cold
  • Stage-1 mapping, 290 Nm @ 50% throttle (50 just to pick a number), not bad for the engine when cold (at least what I've heard).

What's the difference? The engine is producing the same amount of power, so how come one of them isn't favourable with a cold engine, while the other is?

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  • This is turbocharged, right?
    – Zaid
    Mar 1, 2018 at 10:10
  • Also, you should clarify who said that the OEM recommendations don't apply to the Stage 1 tune. Is it the tuner, or is it from anecdotes of owners?
    – Zaid
    Mar 1, 2018 at 10:14
  • @Zaid Yes, this is a inline-four turbocharged 2.0 TDI. When tuning it, I asked the mechanic about it and he told me that thermal expansion and increased torque would not effect anything when driving the car cold
    – Erik
    Mar 1, 2018 at 10:18
  • I'm not sure that his statement implies that you can ignore the OEM recommendation.
    – Zaid
    Mar 1, 2018 at 10:33
  • @Zaid I figure too. I drive it so that it provides normal acceleration for traffic use - just like I would before, and avoid heavy applications before it has reached some temperature.
    – Erik
    Mar 1, 2018 at 10:40

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The tune might reduce the severity of the problem, but it can't cheat physics.

As explained in this answer, redlining while the engine is cold puts undue stresses on the engine that shortens its useful life.

Since this is a turbocharged vehicle, the tune is increasing torque output by increasing boost pressure, which increases operating temperatures:

▲ intake charge pressure → ▲ combustion chamber temperatures

The consequence of this is that at 1200 RPM the engine will warm up faster on the Stage 1 tune than the stock tune.

However, for reasons listed in the linked Q&A, this does not negate the manufacturer's recommendation; there will still be a temperature difference across the combustion chamber and engine block/head while the engine is warming up.

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