Will LTFT go up sligtly with cold temps?

[Luxus Panzer]

Noticed when I drive my car after work when it is cold (approx -8 C today) my LTFT was at 5.5% and about 5 min later when car was a bit warmer it ant down to 4.7%.

I was cleaning oil out of my inter cooler pipes last oil change so I may have bumped a line to somewhere as I was working near the SAI box.


After about 5 min of EASY driving.





After about 10 min of EASY driving.

[old guy]

The ambient temperature definately effects the LTFT. A lot of it has to do with the base tuning. It sounds like yours is slightly toward the lean side. That's why it's adding 5.5% to bring up the ~14.5 A/F when the engine isn't fully up to operating temperature. Then once close to full operating temperature the additive drops back to 4.7% as the A/F increases to ~14.7.

My tuning is toward the rich side so I see adjustments in the opposite direction. In the warmer weather it is generally removing -1.5%→ -2.3%. When it gets cold it typically remains between -3.1%→ -3.9%. When it gets really cold it will will go even richer and the LTFT goes to -5.5% until the engine reaches the normal operating temperature it drops to -3.9%.

With all that being said adjustments in the LTFT between ±10% are considered within the normal operating range. Personally I like to see LTFT adjustments in the ±5% at normal operating temperatures.

If you are concerned with the LTFT's and want to play around with them you can download Unisettings Bosch ME7 and adjust the base map up or down yourself. but be careful because you can do some real damage if you make a bad adjustment. The software assumes you know what you are doing ;-)

[Luxus Panzer]

Right on, thanks.

I will monitor and hope they go back to under 3% in the summer.

[Luxus Panzer]

Went for a much longer drive today at approx the same outside temp (-8 to -10 C)

Things look much better once warmed up :)

[old guy]

LTFT's above or below "0" aren't necessarily a bad thing. It just indicates the variation and consequent adjustment from the base map.

Since I'm running significantly higher boost and air flow than the stock tune I'm perfectly happy with and prefer a small amount of -LTFT. I would much rather have the ECM adjust down from a slightly rich map than up from a lean map. Especially when I go for a hard pull through the gears.

I have noticed that when I lower the base map a little (Unisettings) I start to see an increase in CF's when I hit it hard. I suspect it has to do with the reaction time of the ECM from the wideband O2 sensor reading.

[diagnosticator]

Also, seasonal and regional fuel variations with ethanol and other oxygenating additives, and volatility adjustments effect the LTFTs as does air density,(ambient temps,)

[Luxus Panzer]

Also, seasonal and regional fuel variations with ethanol and other oxygenating additives, and volatility adjustments effect the LTFTs as does air density,(ambient temps,)

Thank god our premium contains no Ethanol here :) Winter additives...not so lucky ;)