High idle issue after ECM swap

[Austin.]

Hey everybody, ive got an 07.5 Silverado with a BTR cam, milled heads, long tubes, Etc. it had a custom tune in it and it ran great for years until this week the ECM randomly went out on it. so i just put a junkyard ECM into it but the new ECM has a different OS so some tables are different. i did the tune compare for the majority and then manually transfered over some of the tables that are different. when i first started it it idled great but the first time i touched the throttle it revved up to 2k rpm and now the idle wont go below 2k rpm. ANY TUNING HELP WOULD BE AMAZiNG i am a very novice tuner. thanks.

[blindsquirrel]

Attachment 132595

[Austin.]

I did everything with the throttle learn,I did the reset with my scanner,let it idle on and off forever,and drove it and its still high idling. When it's cold if I start it it will idle normally forever but as soon as I touch the throttle then it hovers 2k rpm idle. If I stuff it into gear and hold it back with the brakes for 20 seconds it'll finely kick out of high idle and then idle normal and it'll continue to idle normal until I touch the throttle again.

[GHuggins]

It's most likely the background OS that's still in the ecm. Two options are to flash it with tis then reload your tune which due to OS changes may still require some tweaking of things or rework the current tune. You're really better off to have the OS right and tweak if need be vs the latter. It's all up to you at this point as the reflash "may" require re-licensing again as well.

You can even try the long idle relearn - I'm not sure if it still works on the 4th gen or not - you let it idle to full temp - hold foot on brake and pull into drive - wait 5 minutes - put in neutral - wait 5 minutes - put in reverse - wait 5 minutes then back to park. It helps, but I've never had it fully "learn" one.

[blindsquirrel]

What the actual fuck is going on here?

Attachment 132626

[blindsquirrel]

AND, you have the wrong ECM. The junkyard one is for VIN 2GCEK19C681310091, which is a 2008, which should make it a 12612384 ('08-'09). But your file from the original ECM is 3GCEK13387G550483, a 2007, which is a one-year-only 12603892 or 12597121. So you won't be able to program the junkyard ECM with the calibration correct for the truck, if you even had the right tools to do that.

[GHuggins]

Yeah, something was really screwed up on the VE transfer. Good catch on the ecm Blind.

[Austin.]

Ok so sounds like I'm gonna have to scrap the 08 ecm,get an 07 ecm that matches my serial and then refresh onto that one. I was just in a hurry to try and get the truck back on the road so I got the first ecm I could get my hands on. Thanks for all the help guys I've never dealt with any of this before.

[blindsquirrel]

Go to Ebay, search for your correct Service Number plus 'programmed-to-your-vin' (and/or 'vin-programmed'). Sellers on there will SPS a used ECM and mail it right to you most of the time for less total cost than one from the junkyard costs with the wrong calibration in it.