ASV: Short-Term Performance Loss

Hello everyone,

I have a Skoda Octavia TDI, 110 hp, manufactured in 2001, with engine code ASV (EU3). I've noticed the following phenomenon. When I accelerate to approximately 100 km/h and apply full throttle, the engine initially responds strongly, and the instantaneous fuel consumption reading increases to about 13 l/100 km. After about one second, this surge in power noticeably decreases for about one second (fuel consumption then drops to 11.7 - 12.1 l/100 km), before returning to the original value. Interestingly, this only occurs when the outside temperature exceeds approximately 15°C.

Does anyone have an explanation for this? I've been wondering if it might be a "cosmetic flaw" caused by the exhaust gas recirculation system. I'm looking forward to hearing your answers.

mcgregg

Okay, looking at the boost pressure curve of my ALH engine, I suspect the effect comes from the adjustment of the boost pressure.

When the pedal is pressed, the pressure initially overshoots to 1.2 bar before being abruptly brought back down, and then it rises again to the target pressure of 0.9 bar.
Depending on how the VTG (Variable Transmission Gear) is set, the overshoot effect will be more or less pronounced.

At higher temperatures, the smoke pattern could also have a slightly inhibiting effect.

CU Gremlin.

Hello Gremlin!

Thank you for your reply. Smoke map? Presumably to comply with soot emission limits. This morning, I tried it a few more times, because if it's an overshoot, it should also occur at lower temperatures. However, I'm not noticing any of that effect. Also, the fuel consumption display remains at 13.7 l/100 km, which is 0.7 l more than at higher temperatures.

mcgregg

The over-the-top guy is also naturally cold.

But when it's warm, less oxygen enters the combustion chambers. Firstly, the 'fresh' air is already warmer, and secondly, the liquid coolant can't cool it down as much.

You would need to log it to see it precisely.

CU Gremlin.

Hello Gremlin!

Today, I performed some elasticity measurements. In the morning, without any noticeable drop in performance, I achieved 10.8 seconds from 80 to 120 km/h. In the afternoon, it was 11.0 seconds; this time, I made several attempts, on a flat stretch of road, and I took the speedometer deviation into account. So, the difference is within the measurement tolerance, and I also believe I might have stopped the timer a bit too early in the morning.

I'm going to file this under "minor imperfections" for the sake of the environment. I'm probably just being too sensitive, because the drop in performance is really quite small. I'll consult with my Skoda dealer again; the car is going there next week for a timing belt replacement anyway.

Best regards, mcgregg.

Hello.

I also have an ASV in my A3 and I'm experiencing the same phenomenon! It seems to be normal.

Best regards, Hüso.