2010 1500 Silverado 4x4 LC9 5.3 tuned by Blackbear
No codes .truck starts runs perfect ...Justin sees no issue with fast idle in tune
it does have headers and AirRaid CAI


Have this issue last 2 winters when it gets cold

Problem .... fast idle does not come back down to stock idle 525 in gear once truck warms up ...I understand once coolant temp at 143* idle should return to normal ie. 525rpm in gear ..... it only comes down to about 725

the colder the outside temp is the higher the engine temp needs to be for fast idle to come off ....sometimes it comes back to 525 at about 170* buy in cold weather it needs to above 194* to come off and even then be at 194+ for a long time ....... "if "I turn ignition key off once truck at 194* then restart it idles right down to 525 immediately and even if I turn off truck for an hour or so the fast idle works as normal comes off at 143* so only seems to be an issue on first start of day until fully warmed up

Changed T-stat .... changed coolant temp sensor in drv side head .... cleaned TB did TPS relearn ...... no change

I am told that only the coolant sensor controls this but it seems to me that outside ambient has something to do with it as only very cold day with wind it can stay on high idle even when truck at 190

Any chance the AIT sensor or even that outside temp sensor in grill effects the idle ....... or since I have the cai is the intake seeing too much cool air

Sori for long post .... driving me nuts nobody can figure out

 

Can you post your tune and a log?

What throttle body is on it, and has it been ported?

 

Stock TB not ported etc ........... not sure I know how to post a log but will try ........have the logs that I sent Justin @ BB

 

Find someone with HP Tuners (scanner) or a Tech 2 and have them do a TB Clean Reset. May not fix it but is a simple procedure to try. I've fixed a lot of GMT 900 trucks that idle high with it.

 

Done that a few times have access to Tech 2 ....... this is not a regular high idle ..its the cold fast idle not coming all the way off when engine warms up

 

I remember you having this issue, subscribing as I would love to hear the solution.

 

It would be very helpful to see the tune. Or at least know what operating system you are using.

 

Don't know if I can post the tune, sori......tune via EFI live Autocal from Blackbear .he has looked at it and did not see an issue ....or at least never was able to correct .........I have the log files on another laptop at shop will get them and try and post ........ have had the BB tune since truck new the issue only last two winters .......... does the ait sensor give input to control the fast idle ?? I have scan guage in truck can monitor most parameters

 

Does it idle down normally if you load up the stock tune? Don't have access to a PC this week, but you can download EFILive and get a stock 2010 5.3 tune from tunefiledepot. Then you can take a look at all the idle tables to see how it is brought down.

 

Yes I have thought about that and I do have the stock tune saved on my laptop just not sure how to save and reinstall my current BB tune ........ I agree it makes sense to do that before anything else .will have to figure out how to do

It appears that you folks feel its in the tune , ........ so it does not make sense that the ait sensor or the tps is causing the issue ........ as the weather warms up the problem does not happen the fast idle comes off at 143*f which is what the stock tables show it should