TJ getting 5-6 mpg

[AndyG]

5 to 6 miles per gallon....Go ahead, rub our noses in the great mileage you’re getting- You’ll probably tell us next that your wife gave you a credit card to get more parts.

 

[pagrey]

It is entirely possible that with those cold temps combined with the short drive time that the engine never warms up enough to get into closed loop.

Open loop just waits for the 02 sensor heaters which takes just seconds in even the coldest climates. It'll run rich as hell in really cold weather but the sensors will be working.

 

[pagrey]

Most fleet services agree 100% about not letting a vehicle idle. The thing I notice is that some people take that as hop in and go while most fleet managers seem to recommend no more than 30 seconds. Personally I like waiting for closed loop which is about a minute. But what I notice is most people wait less time than it takes the oil pressure to register after an oil change, not that that's what's happening but generally less than 10 seconds which isn't what I feel anybody meant by "no need to let warm up." Just an observation, certainly not suggesting anybody sit and wait for 200 or arguing a point. I just rarely see anybody even wait what I'd call a "beat" these days and I think closed loop is a rational minimum.

 

[Jezza]

Open loop just waits for the 02 sensor heaters which takes just seconds in even the coldest climates. It'll run rich as hell in really cold weather but the sensors will be working.

I know if the computer is still in cold start enrichment it won't enable closed loop feedback. It would be counterproductive to add fuel only to have the trims back it out again. When I lived in South Dakota years ago there were days I could drive to work and back never reaching closed loop.

 

[pagrey]

When I lived in South Dakota years ago there were days I could drive to work and back never reaching closed loop.

Wow, good to know. I stand corrected.

 

[Jpitty]

Some interesting info here, got me reading up in o2 sensors , and open/closed loops now..good stuff thanks .

 

[The shuggs]

At best 30 seconds is all you need to idle to get oil splashed around inside, unless you're dealing with extreme cold. When it's cold out, I just idle until the coolant temperature gauge starts to move. It might be longer than necessary, but it guarantees that is warm enough. The engine is going to warm up a lot quicker under load anyways. Getting the needle to move ensures that there's no load on it when it has the least lubrication.

 

[The shuggs]

I found this picture of one of the rentals I was using for work. Idling for the better part of 12 hours in -30°C does a number on the estimated range.