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juld0zer · 04-27-2014, 10:42 PM

After a lot of observation and experimentation, i have concluded that there are 3 temperatures which affect engine response. In order of severity/likelihood/nuisance (2 and 3 should be on par in terms of severity):
1 - Intake Air Temp
2 - Engine Oil Temp
3 - Engine Coolant Temp

Most of the lag people experience is due to high intake air temps, resulting jn the ECU pulling timing to prevent detonation. This includes lag due to heatsoaked IAT sensor and intake components leading to inaccurate data fed to ECU, pulling timing and causing the engine to run slightly leaner (cooler air is denser). High IAT i think is the cause of the bogging/dead/car is thinking feeling when taking off and it feels like the engine is unwilling to budge. I'm sure you know what i mean. I've gone to great lengths to eliminate IAT related lag so i'm confident this is not the cause of the remaining lag i experience.

Based on the dash oil temp gauge, i feel a lag in throttle response at 96*c/205*F and above. This can be observed in mild ambient temps (less than 24*c/75*F) so it's not high IAT causing the lag. I can notice the lag by doing the gas pedal jab test. Revs rise slightly slower and fall slightly slower than with a cool engine (oil temp at 90*c or less). I can really notice the lag while taking off. It feels like the aircon is on (i rarely use aircon as i prefer fresh air). Sort of like pushing the pedal further and not getting much more acceleration.

High engine coolant temp (let's just define it as 95*c and up) is usually experienced by people in stop start/heavy traffic driving conditions. Lack of fresh airflow, high ambient temp, lack of engine bay ventilation all contributes. So does the default cooling fan temperature threshoulds. The end result is hot, trapped air inside a cramped engine bay. Radiant heat is your enemy here. Intake components get heated up and timing gets pulled as a result. Coolant temp also plays a role in detonation management.

Oil and coolant temps are usually within a few degrees of each other when i feel the lag.

04-27-2014, 10:42 PM	#102 (permalink)
juld0zer Enthusiast Member Join Date: Nov 2012 Location: Sydney Posts: 428 Drives: 11 Nissan 370Z MB M6 Rep Power: 138	After a lot of observation and experimentation, i have concluded that there are 3 temperatures which affect engine response. In order of severity/likelihood/nuisance (2 and 3 should be on par in terms of severity): 1 - Intake Air Temp 2 - Engine Oil Temp 3 - Engine Coolant Temp Most of the lag people experience is due to high intake air temps, resulting jn the ECU pulling timing to prevent detonation. This includes lag due to heatsoaked IAT sensor and intake components leading to inaccurate data fed to ECU, pulling timing and causing the engine to run slightly leaner (cooler air is denser). High IAT i think is the cause of the bogging/dead/car is thinking feeling when taking off and it feels like the engine is unwilling to budge. I'm sure you know what i mean. I've gone to great lengths to eliminate IAT related lag so i'm confident this is not the cause of the remaining lag i experience. Based on the dash oil temp gauge, i feel a lag in throttle response at 96c/205F and above. This can be observed in mild ambient temps (less than 24c/75F) so it's not high IAT causing the lag. I can notice the lag by doing the gas pedal jab test. Revs rise slightly slower and fall slightly slower than with a cool engine (oil temp at 90c or less). I can really notice the lag while taking off. It feels like the aircon is on (i rarely use aircon as i prefer fresh air). Sort of like pushing the pedal further and not getting much more acceleration. High engine coolant temp (let's just define it as 95c and up) is usually experienced by people in stop start/heavy traffic driving conditions. Lack of fresh airflow, high ambient temp, lack of engine bay ventilation all contributes. So does the default cooling fan temperature threshoulds. The end result is hot, trapped air inside a cramped engine bay. Radiant heat is your enemy here. Intake components get heated up and timing gets pulled as a result. Coolant temp also plays a role in detonation management. Oil and coolant temps are usually within a few degrees of each other when i feel the lag.