I've read where pre Sept 04 engines should be reflashed. I have 8,000 miles on it now and noticed my mileage dropped off around 4,000 miles, from 19 to around 15 or 16. THIS WAS IN WARMER WEATHER. This is bone stock and treated with TLC. I will be going on a 5,000 mile trip the first of January and scared of opening a can of worms. Truck runs fine just drop in mileage. SUGGESTIONS PLEASE (newbie to diesels)

SSGREG, Howdie neighbor...It's been getting cold lately. I've heard the same complaint from other diesel owners about wintertime mileage. I've dropped from 17mpg to 15-16 in the last tank. As for reflash...I just rec'd 3 updates today at Bowman Chev. The only problem that I knew about was the low RPM pulsing surge between 5 and 10MPH. Why not get it?

If your truck is eligible for it and you have not gotten the flash, GET IT. As for the mileage it will drop with winter blended diesel.

Eric

In addition to blended fuel, another thing I've notice that affects my mileage is driving in temps below 32deg F without the winter cover in place. Mileage picked up as soon as I slipped on the front grill cover for the first time. With outside temp at about 14deg F my mileage was 13-14mpg w/o cover, it returned to normal 16-17+mpg with cover installed. It's very important to keep a diesel engine running warm to achieve efficient fuel combustion. The winter cover should be taken off whenever the weather warms back up > 32deg or it can cause a reverse affect in mileage and possibly even hurt the engine (overheating).

BTW- I think my outside temp readout (on the mirror) seems to register several degrees higher when I have the winter cover installed. Has anyone else seen this? Is it normal, or is it my imagination?

-AJ

I would say go get the update because the longer it is left the worse the symtoms will get and eventually you may have to replace injectors. if you have no problems now then you shouldn't have any after the flash. Most of us with the symptoms end up having bad injectors while others just get the flash and it fixes it. Mine started dropping mileage, then there was teh smoke, then the surging..blah blah.. I would get it done before your trip.

just my $.02

ssgreg .. Your note does not say if your 2004 is an LB7 or an LLY. You probably know this already, but if not, the reflash is for the newer LLY engine.

I had the reflash done recently and the engine is noticably quieter than before and it just seems smoother overall. I have not driven it much since the reflash, but so far so good. I was not having any MPG issues like you before the reflash, so I do not expect much change in that area for my truck.

Seems like there are more notes posted by people that are happy about the reflash than those who are having problems. Many of those reporting problems have other issues (injectors, etc.) unrelated to the flash. If you are having problems now, then the reflash is the first step in getting the problems resolved.

BTW- I think my outside temp readout (on the mirror) seems to register several degrees higher when I have the winter cover installed. Has anyone else seen this? Is it normal, or is it my imagination?

-AJ[/QUOTE]

The winter cover may be causing the sensor to pick up some heat from the engine. Just a guess.

QUOTE: ajarthurBTW- I think my outside temp readout (on the mirror) seems to register several degrees higher when I have the winter cover installed. Has anyone else seen this? Is it normal, or is it my imagination?

Its because the temp sensor is located behind the grill in front of the radator, when you put the cover on it holds the heat inside.

Bingo... Thanks!

So I just drive up to the dealership and ask for a reflash?

Mine is running fine. I have noticed the surge everyone complains about but it only surges for a couple of times at low speed then it smoothes out no matter how slow I drive it


Mark

I would get it, runs a lot better.

tHANKS FOR THE SUPPORT, WILL GET IT NEXT WEEK AND REPORT BACK, gREG