So the issue I've been having with reduced power and low gas mileage has returned, still no codes, everything is pretty much running within spec based on my scanner.
We had some real decent weather the past few days (60F )and I noticed that my car is still taking about 5+ minutes for the idle RPMS to come down from the 1100 rpm range to the normal +/- 650 RPM range.....during this time, I can see the fuel economy on my screen dropping at a quick rate. It went from 12.5 mpg down to 9.4 mpg during that span - this cannot be normal.
I did some digging on closed vs open loop and I found something that I suspected regarding my coolant system. If my thermostat is stuck open, then it would cause all the issues I've been having including the extremely long time to get the engine up to operating temps. I originally thought it would have been my ECT sensor, but I haven't seen a code for this.
So I'm going to buy a new thermostat - any recommendations? I've seen 170F and 180F (OEM) thermostats - any recommendations?
And is there a way for me to change the thermostat on this engine without draining all the coolant? I doubt it, but it would be nice...
5.6L Thermostat...
Re: 5.6L Thermostat...
I would stick to the specified 180F thermostat, and go for a genuine OEM part as well.
If you think about it, using a colder T-stat is like having a jammed open thermostat as far as the ECU is concerned, and you would have the same warm-up issues you are trying to solve...just more consistently.
Btw, at some point of a malfunctioning thermostat, the OBD2 system will report a code. Thankfully I've never had to find out exactly at what point this happens.
If you are not ready to commit to thermostat removal or the sure-fire way of boiling it in a pot, there are things you can do to troubleshoot in place, such as checking the hose temperatures.
While there, check to ensure your cooling fans aren't running constantly.
If you think about it, using a colder T-stat is like having a jammed open thermostat as far as the ECU is concerned, and you would have the same warm-up issues you are trying to solve...just more consistently.
Btw, at some point of a malfunctioning thermostat, the OBD2 system will report a code. Thankfully I've never had to find out exactly at what point this happens.
If you are not ready to commit to thermostat removal or the sure-fire way of boiling it in a pot, there are things you can do to troubleshoot in place, such as checking the hose temperatures.
While there, check to ensure your cooling fans aren't running constantly.
Re: 5.6L Thermostat...
The thermostat is pretty high in the coolant system. You'll lose a lot of coolant, but most of it will still be contained below that point (engine block, radiator.. )
For most people, it would be a good time to flush/replace the coolant though.
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