Wierd block heater issue

[Kelle]

Hi. I recently purchased a 2008 silverado 1500 5.3l and I'm trying to solve a very bizarre issue. So when I dont plug the truck in, it starts great no matter what the temperature is. Even down to -35 it still starts fine. The issue is when I plug in the block heater. If I plug it in overnight and try to start it, it chugs and misfires like a diesel on a cold start. It'll even sputter and die sometimes. Doesnt throw any error codes. I've never seen any vehicle have issues starting by plugging in the block heater. I had a 2009 4.8 that would think the engine was overheating if you plugged it in. It would turn the ac off and turn the electric fans on. I feel like it has something to do with a wacky temp sensor or something. Anyone experience something like this before?

[riverbanks]

The i.a.t. and c.t.s. are not telling the same story to pcm, confusion,if it is before 6 hrs,no problem,after,that is called the "soak"they should be telling the same story,parameters are set to close in pcm,I think 30° is the worry point

[CamGTP]

Yeah, I've run into that a few times but nothing that bad. My 2012 truck would fire right up, then bog and catch itself before returning to a normal idle. Having my trucks block heater on a timer helped because it still kept the coolant warm but didn't let it stay on the whole entire night.

[riverbanks]

Smart, not to much heat, just a scooch

[sefiroxx]

Heaters are probably putting the ecuv into closed loop. Try disconnecting the temp sensor on start up to force an open loop

[ACE12345]

I have a similar issue with an 07 volvo S80 V8.

I use a timer and run power to the block heater (BH) for 2h from 3:30 to 5:30 I start the vehicle between 5:31 - 5:45, outside temperature is anywhere from 15 to 30F. On start up the engine chugs like I have an after market cam but never dies. My intent of using the BH is for better engine life and a quicker warm up time. My morning commute is only 7mi and I imagine I get heat just a little quicker with the BH. Starting without the BH I have no audible engine hesitation.