Yukon Hybrid/Strange Cold start issue

[YWGBrid]

Hey guys,
I have this odd issue on my yukon hybrid. When its super cold in Canada my truck will not start. What i mean by this is i turn the key (or remote start) truck goes right to wide open throttle and shuts off as it hits the protection. NO matter what i do it will not start. At first i thought the remedy was that that block heater was not plugged in ( but it was and is working ) There are 0 codes on the truck, there is nothing odd. I checked the throttle body learning etc. its ok.Once the temperature outside increases there is no problems all. Truck starts will idle at around 1200 ish and no issues . I am truly stumped.

I found this thread

Engine Revs to Redline on Cold Start 6.2L

www.gm-trucks.com

But no one seems to know the issue including the dealer. ITs honestly bizzarro.

 

[Foggy]

You will need a data scanner to give you live data
Check your coolant temp sensor and your TPS values - throttle position sensor
You may have a stuck throttle motor.
IDK squat about electric vehicles ....

 

[Foggy]

That article refers to the newer gen 5 engines and different systems in the
newer trucks... Would not relate to our gen 4 stuff at all.
Although I don't see any info in your signature or post on what year etc you have

 

[B-train]

I would look at the throttle body to see if it's coked up with carbon. Maybe it's getting hung up as all the components shrink due to the cold.

 

[j91z28d1]

yeah, you're going to need a scanner forsure. at least one you can see the throttle position on. but honestly, these hybrids as they are getting older like anything start to have some issues, most are probably simple but you just don't know.. dealerships are useless with these, you might find a local tech that cares enough to actually follow troubleshoot tree on his software. but mostly you're on own with them. I have 3 different scanners for this truck I keep handy, cheap 30$ Bluetooth one and torque app with some extra pids just for super eazy of use. another 70$ Bluetooth one that is a bidirectional one, it's more clunky software wise but does a lot of stuff that's handy to keep in the truck. and then a tech 2. if I was going to pick just one, get a 300$ clone tech2. I joke they should come with one in the glove box lol. that and a 20$ access to diy all data and you can basically trouble shoot 80% of these trucks on your own with Google searches and bouncing ideas off guys on the boards.

does your tach on the dash actually hit redline or could it just sound like it. I've seen quite a few threads where people think the engine is running and racing, but it never even started. Just the electric motor spins the motor over so fast for about 10sec before it shuts off, that people think it's running when it's not.

 

[YWGBrid]

You will need a data scanner to give you live data
Check your coolant temp sensor and your TPS values - throttle position sensor
You may have a stuck throttle motor.
IDK squat about electric vehicles ....

Thanks will try to do that. Its just super odd issue. I found guys had it with the 6.2 alot but there was no deffinate result as to why it was doing it. I did change the coolany temp sensor as this made the most logical sense. ITs somewhat kicking me trying to figure out what it is as when the car warms up there is no issues what so ever. I do not think its hybrid related as the hybrid system is fairly basic.

 

[j91z28d1]

only hybrid related thing and revving up that I've found any posts about is if they battery is completely shot like been throwing codes for a while, after a crank the engine will have to Rev up to try and keep everything running and get the batteries back to a usable voltage. if you don't wait a bit, guys complain it will try and push thru the brakes when coming to a stop because it's reved up.

but that doesn't fit your's at all. for it to max Rev and die out. that's an odd one. does it keep. doing it if you restart? a scanner has a target or desired rpm. which should atleast tell you if it's something the ecm is commanding for some reason. if not, the only way for it to Rev up is air getting into the intake, either by a bad throttle body, or something else. maybe a crazy intake manifold leak when the rubber gasket is cold, but seals up when it warms up?

 

[BG1988]

only hybrid related thing and revving up that I've found any posts about is if they battery is completely shot like been throwing codes for a while, after a crank the engine will have to Rev up to try and keep everything running and get the batteries back to a usable voltage. if you don't wait a bit, guys complain it will try and push thru the brakes when coming to a stop because it's reved up.

but that doesn't fit your's at all. for it to max Rev and die out. that's an odd one. does it keep. doing it if you restart? a scanner has a target or desired rpm. which should atleast tell you if it's something the ecm is commanding for some reason. if not, the only way for it to Rev up is air getting into the intake, either by a bad throttle body, or something else. maybe a crazy intake manifold leak when the rubber gasket is cold, but seals up when it warms up?

bad oring on the snorkel tube ...