Any GM techs here, HELP ..fast idle problem nobody here can solve
#1
Any GM techs here, HELP ..fast idle problem nobody here can solve
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
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
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#8
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
#10
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