2 replies to this topic

[Dave_GSR1.8]

So, I recently discovered my radiator cap was no longer holding much pressure; it must have been that way for a while as I had been chasing a slow loss of coolant (but with no signs of any coolant leaks) for a month or so. The interesting thing is that with a new radiator cap the fuel consumption has improved significantly (ie gone from 9 to 10 km per litre). So is this possible ? Radiator is certainly much hotter than previously, so could it be that the ECU is detecting a warmer engine and running the engine leaner (as it no longer reading the engine as too cool and therefore thinking it should run it richer for colder running ) ?

 

The fuel consumption change is based on only one tank (and driving conditions probably not consistent between tanks) so its early days yet, I'll know better after a few more fills, but this was a surprise!

[jack be nimble]

Ecu will go into closed loop with a warmer engine. Although closed loop is not the most economical running, it may be better than the open loop settings

[evo-gsr]

So, I recently discovered my radiator cap was no longer holding much pressure; it must have been that way for a while as I had been chasing a slow loss of coolant (but with no signs of any coolant leaks) for a month or so. The interesting thing is that with a new radiator cap the fuel consumption has improved significantly (ie gone from 9 to 10 km per litre). So is this possible ? Radiator is certainly much hotter than previously, so could it be that the ECU is detecting a warmer engine and running the engine leaner (as it no longer reading the engine as too cool and therefore thinking it should run it richer for colder running ) ?
 
The fuel consumption change is based on only one tank (and driving conditions probably not consistent between tanks) so its early days yet, I'll know better after a few more fills, but this was a surprise!

You've pretty much answered your own question Dave. Your theory is pretty much spot on.