Datatek
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P38 Modulation checks with diagnostics.
Following on from my post asking about the variation of modulation with coolant temperature and my post about the effect of modulation on hot starting, this post highlights the variation of modulation with coolant temperature on 2 cars.
Way back I established that running temperature with the viscous fan and cowl in place was between 90 and 95C, I did this to establish the temperature at which to set the stat for the electric fans mod. My tests cover from cold to 95C on one car and to 100C on the other and correlates the variation to the position of the temperature gauge needle. I can find no correlation in variation to fuel temperature (there is a fuel heater in the filter head) which always ends up around 43C. There is no significant cooling of the FIP from the viscous fan for two reason, firstly the FIP is out of any airflow as it's well hidden behined the cam chain case, secondly blowing air at 90C+ over an object that is at 43C is going to raise the temperature not lower it. The tests were done with the bonnet open avoiding heat build up under the bonnet. Thus the absence of the viscous fan & cowl and the electric fans are not relevant to the fuel temperature.
The gauge on both cars is one minute to 12 from just over 85C to 100C Probably to 105C as Roman rob states, as can be seen from the tables, the modulation varies considerably between 85 and 95C. Thus for us amateurs, checking modulation with diagnostics and using the dash gauge to judge “up to temperature” can be very misleading and IMO modulation should be checked at a minimum of 90C as shown by diagnostics. I take 95C as the temperature for checking.
Following on from my post asking about the variation of modulation with coolant temperature and my post about the effect of modulation on hot starting, this post highlights the variation of modulation with coolant temperature on 2 cars.
Way back I established that running temperature with the viscous fan and cowl in place was between 90 and 95C, I did this to establish the temperature at which to set the stat for the electric fans mod. My tests cover from cold to 95C on one car and to 100C on the other and correlates the variation to the position of the temperature gauge needle. I can find no correlation in variation to fuel temperature (there is a fuel heater in the filter head) which always ends up around 43C. There is no significant cooling of the FIP from the viscous fan for two reason, firstly the FIP is out of any airflow as it's well hidden behined the cam chain case, secondly blowing air at 90C+ over an object that is at 43C is going to raise the temperature not lower it. The tests were done with the bonnet open avoiding heat build up under the bonnet. Thus the absence of the viscous fan & cowl and the electric fans are not relevant to the fuel temperature.
The gauge on both cars is one minute to 12 from just over 85C to 100C Probably to 105C as Roman rob states, as can be seen from the tables, the modulation varies considerably between 85 and 95C. Thus for us amateurs, checking modulation with diagnostics and using the dash gauge to judge “up to temperature” can be very misleading and IMO modulation should be checked at a minimum of 90C as shown by diagnostics. I take 95C as the temperature for checking.
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