Have an 07 Yukon Denali with 220k mi. An issue has arised that has stumped 5 yes 5 GM specialists. When you do a cold start in the morning the truck fires right up and sounds great will high idle for a few seconds then drop into a steady idle then about a minute later the truck shuts off and a stabilitrack, traction, reduced power lights come up but with no codes. If you try to start right back up will not crank. Turn off key for a minute then try again fire right up with no lights until it stalls again. It will continue to do this until the engine hit 210 degrees then it stays running and runs very good all day even if it cools down. Next Morning same thing. You can start truck on first cold start and hold throttle at 2k rpms until it heats up to 210 degrees and it will not shut off. NO CODES!!! Replaced all negative grounds and added some with no change. Replaced MAF Sensor and TPS with no change. Replaced battery and alternator with no change. Replaced radio interface module with no change as that was a no-start problem before with Sony Radio. Runs extremely well once the 210 degrees is reached upon 1st morning cold start. Even idles well and revs well before its warmed up but will shut down after about a minute of idling as if you turned off the key and there is no hiccup, it just shuts off. There is over 10 hours diagnostic time between 5 mechanics and all of them said the same thing....there is nothing wrong they can find. Maybe someone else has had this problem and can help. Thanks in advance for any help.
07 Yukon Denali won't stay running till warm then fine all day?! Till next morning...
- Thread starter ironeater
- Start date
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Are you saying that it won't crank (the starter doesn't turn it over) after it initially stalls? Or are you saying that it does crank but doesn't fire up?
How long has it been going on (miles and days/months/years). Did this problem start soon after any work was done on the truck? If so, what work?
You'll probably need to be looking at some live data. For starters, when it's cold and bound to act up, before starting it compare the Engine Coolant Temp and the ambient or engine temp (the engine block temp can be read with an infrared temp gun). Watch them as it starts to see if the ECT reports properly.
Has the throttle body been cleaned lately?
Yes will not crank when stalls till you turn off key and wait a min then starts fine. Has new Throttle body and throttle position sensor and that did make it run better(rev cleaner) at high rpm but did not change problem. The old throttle body was pretty clean when removed. This problem showed up about 2 months after fixing the radio interface module which was 3 months ago. Changed all the grounds, battery, throttle body, throttle position sensor in the last 4 days.
