Reluctant upshift to 3rd while cold (auto trans) - Toyota Yaris Forums

07WYarisRS · 08-31-2006, 12:41 AM

Most fuel injected engines are designed to run with very little to no warm up but how you drive or operate the engine for the first 5 minutes will greatly affect how well and how long the engine lives.
Aluminum pistons and steel cylinder expand at much different rates. An aluminum piston will exspand faster and that can cause serious issues with clearance and causes 4 point scuffing and cold seizures in the worst cases.
ALL the fuel injection system does is dump in an extra rich mixture to help the engine warm up faster regardless if you are driving or not. This extra rich mixture is less harmfull to the cars emmisions system if you are operating under load (when more fuel is being used and not waisted) then just idling.

BUT that being said the person that lets his engine idle for 30 seconds a minute or so is not going to shorten the life of the engine or any components by letting it warm up for a bit.

Operating any engine outside of normal operating temps will shorten the life of the engine, the harder you drive it outside of normal operating temps the faster it will wear it out.
the "COOL" indicator in the gauge cluster is a great indicator of when the engine is warmed up and can be driven normally.

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08-31-2006, 12:41 AM	#17
07WYarisRS HardlyDangerous Drives: 09 Yaris LE, H/B, auto Join Date: Jul 2006 Location: Ridgeway Ontario Posts: 573	Most fuel injected engines are designed to run with very little to no warm up but how you drive or operate the engine for the first 5 minutes will greatly affect how well and how long the engine lives. Aluminum pistons and steel cylinder expand at much different rates. An aluminum piston will exspand faster and that can cause serious issues with clearance and causes 4 point scuffing and cold seizures in the worst cases. ALL the fuel injection system does is dump in an extra rich mixture to help the engine warm up faster regardless if you are driving or not. This extra rich mixture is less harmfull to the cars emmisions system if you are operating under load (when more fuel is being used and not waisted) then just idling. BUT that being said the person that lets his engine idle for 30 seconds a minute or so is not going to shorten the life of the engine or any components by letting it warm up for a bit. Operating any engine outside of normal operating temps will shorten the life of the engine, the harder you drive it outside of normal operating temps the faster it will wear it out. the "COOL" indicator in the gauge cluster is a great indicator of when the engine is warmed up and can be driven normally.