I purchased a new 2004.5 LLY in August 2004. I haven't had any trouble what so ever with it to this date. I do notice when going above 2500 rpm's the loud diesel sound. After doing alot of reading here at this site, I am wondering if I should have my PCM reflashed with all the latest? My truck get about 17 MPG
and runs pretty strong now. I do worry about the loud knocking noise above 2500 RPM's tho. My truch has 9,000 miles on it as of now. I have made an appointment with my dealer 6/6/05 for a reflash. I would like to get some of your opinions of what to do.

Thanks

The additional noise above 2,500 RPM is the pilot injection shutting off. It is perfectly normal. My truck too runs fine with no problems so I have not taken it in for the reflash.

If it ain't broke - don't fix it!!

If it ain't broke - don't fix it!!
:exactly:what I was going to say. I never got the re-flash and my truck runs fine with the stock tune.

15,000 on mine today, no reflash and not one problem.

I run with the "ain't broke don't fix it" train of thought as well.

For 99.9% of the time I agree that if it isn't broke don't fix it. But we are talking about a reflash. I have 33K on my LLY and had it the reflash done a month or two ago. Didn't hurt a thing and now I don't have to here that damn noise. JMHO.

Greg

We had this discussion several months back. IIRC we conducted a poll as to whether to reflash or not. I can't recall the exact numbers, but IIRC an overwhelming majority of those that reflashed posted positive results. :confused:

Best to do a search on the forum and judge for yourself. ;) With the advent of PCM's that control just about everything on these trucks reflashes are used to adjust operating parameters, fix problems, etc.

IIRC the reflash you are looking at adjust injector balance rates, addresses low idle surging and several other mods. :rolleyes:

Much like you my truck ran fine and I was VERY hesitant to fool with it. Based upon what I read on the DP and figuring GM wouldn't change something unless it needed it I had my truck reflashed back in December 2004. My SOTP impression was my truck seemed to get the power to the wheels better after reflash, the Ally seemed to like it to, low idle surging was gone, all plus's. It also seemed to tow better, more power to the wheels. :cool:

I'm happy with it. Some didn't have as favorable an experience. Your truck though, good luck! JJ :)

I will somewhat backtrack here to say that *if* my truck had the symptoms that the reflash addresses, then yes I would get it done.

Mine doesn't have those issues and if yours doesn't then stay with "ain't broken"

Mine was running fine, but I had the refash done anyway just to get the current calibrations. No regrets, the truck runs better and quieter. The difference is not huge, but noticeable.

Hell, good ole JJ sells it so good that I am considering getting it just for S&G's

took mine to dealer for the re-flash. Hated the low end surge. Now surge is gone and truck seems to run better than before.

Ditto what Zaza said! :) TxC, have you forgotten how dangerous following ol JJ's advice can be? :confused: ):h

Question you have to ask yourself punk is do you feel lucky! Well do you? :weld: :eek2: Ouch that hurts! ):h JJ

what are the symptoms of needing a reflash on the ecm? I have seen talk about
surging at idle. Does this occour when the truck is at idle and in gear?

My truck would lunge while moving at idle speed or at very low RPM's(under 1000). Would almost feel like it was bucking a little. After reflash it went away, engine ran smoother, just felt better. My .02 worth. JJ :)

just got truck back with reflash. cant tell the difference. say mpg and same power.

oteo125, since you have an 05 your truck may have the most recent reflash for the LLY. The 04.5's with the initial run of LLY's seem to benefit moreso from the reflash. ;) Does it seem to run quieter to you? :confused:

Please tell me you are not using your "DIC" to compute mpg's? Best done by hand using the DP MPG Calculation Method bro! ):h JJ :)

nothing seemed to change. its the same truck.

reflash it...my MPG went up and the truck runs better hands down. I thought it was fine before it was done but after it made a difference.

i just had mine done today so maybe i need to give it more time. i did drive about 50 miles and mpg didnt seem to change.

Does it cost to have the re-flash done and what should I tell the "sealer" to do when I take the truck in? It's due for PM anyway. It does have times where it has almost like a skip in it when going down the road.

oteo125, the results are pretty much immediate, no break-in time. IIRC most trucks that were built after Sept 04 came with the PCM updates the reflash provided. Didn't hurt anything though. :o:

Baron33, if your 2004 has the LLY you might update your sig to show 2004.5 since the LB7 was the initial engine for the 2004 model year. ;) No cost for reflash, just tell the service advisor you are having low idle surging and ask them to reflash it. If they give you a hassle just ask to see the service manager and go up from there if you have to. Later. JJ :)