Dealer not honoring warranty work..2018 5.3 Yukon issues

[kbuskill]

Dmitry, are you saying that your catalytic converters are up over 1200 degrees after idling for say 20-30 minutes after the engine has reached temperature?

I have sat in a passenger seat and watched my cats before. Accelerating on the highway they easily climb up to the 1500s and then begin to slowly cool and at around 70 mph settle into the 1200-1300s on level ground. They'll quickly heat up going over a hill (bridge) and then begin to slowly cool down again.

Myself and @kbuskill have talked about cat temps before and posted our findings somewhere on this here forum.

I can't recall the exact temps but if I remember correctly the cats should be somewhere in the 700° range after idling for an extended period of time... I haven't looked at mine in a while and I didn't commit it to memory.

 

[smokey_mountain]

Just to make sure we are talking about 700 degrees Celsius or Fahrenheit when they are in idle? I did not wait for 20 mins to measure them but when I drive on the even flat surface they are in 1300-1480 F (705-770 degrees Celsius). I will let them idle for 15-20 mins and measure.

I found a correlation that shaking in D at a stop is much worse immediately after driving hard (e.g. on a highway, up the hill) and then coming to a stop while in D. Somehow engine gets much hotter in those driving conditions and that causes distinct rough idle immediately after that. Am I correct that it points more to fuel supply related than ignition related? I read somewhere that ignition issues usually improve as engine get hotter, and fuel is opposite?

Thank you James and Ken for your data on cats!

I can't recall the exact temps but if I remember correctly the cats should be somewhere in the 700° range after idling for an extended period of time... I haven't looked at mine in a while and I didn't commit it to memory.

Dmitry, are you saying that your catalytic converters are up over 1200 degrees after idling for say 20-30 minutes after the engine has reached temperature?

I have sat in a passenger seat and watched my cats before. Accelerating on the highway they easily climb up to the 1500s and then begin to slowly cool and at around 70 mph settle into the 1200-1300s on level ground. They'll quickly heat up going over a hill (bridge) and then begin to slowly cool down again.

Myself and @kbuskill have talked about cat temps before and posted our findings somewhere on this here forum.

 

[swathdiver]

Just to make sure we are talking about 700 degrees Celsius or Fahrenheit when they are in idle? I did not wait for 20 mins to measure them but when I drive on the even flat surface they are in 1300-1480 F (705-770 degrees Celsius). I will let them idle for 15-20 mins and measure.

I found a correlation that shaking in D at a stop is much worse immediately after driving hard (e.g. on a highway, up the hill) and then coming to a stop while in D. Somehow engine gets much hotter in those driving conditions and that causes distinct rough idle immediately after that. Am I correct that it points more to fuel supply related than ignition related? I read somewhere that ignition issues usually improve as engine get hotter, and fuel is opposite?

Thank you James and Ken for your data on cats!

My pleasure Dmitry. Comments on cats are in fahrenheit. Overall your temps don't seem out of line compared with mine, which is a different generation. However, one side of your engine was hotter than the other when you posted that data log.

 

[kbuskill]

Just to make sure we are talking about 700 degrees Celsius or Fahrenheit when they are in idle? I did not wait for 20 mins to measure them but when I drive on the even flat surface they are in 1300-1480 F (705-770 degrees Celsius). I will let them idle for 15-20 mins and measure.

I found a correlation that shaking in D at a stop is much worse immediately after driving hard (e.g. on a highway, up the hill) and then coming to a stop while in D. Somehow engine gets much hotter in those driving conditions and that causes distinct rough idle immediately after that. Am I correct that it points more to fuel supply related than ignition related? I read somewhere that ignition issues usually improve as engine get hotter, and fuel is opposite?

Thank you James and Ken for your data on cats!

Yes, as James already said... that is 700° F and that is after idling for an extended period of time... if my memory serves me.

 

[smokey_mountain]

Oh, if 700 F I have never seen this temp when engine is running. I will warm it up and let it idle for 15-20 mins tomorrow. Thank you.

My pleasure Dmitry. Comments on cats are in fahrenheit. Overall your temps don't seem out of line compared with mine, which is a different generation. However, one side of your engine was hotter than the other when you posted that data log.

Yes, as James already said... that is 700° F and that is after idling for an extended period of time... if my memory serves me.

 

[smokey_mountain]

I am trying to fix the issues on my own. @Bob2C had some success with his truck and CRC GDI cleaner. I found a thread on the gm-trucks and they recommend using this line here: https://www.gm-trucks.com/forums/uploads/monthly_03_2016/post-129450-0-16852400-1458543187.jpg

Any advice from anyone on that place to spray CRC GDI Intake Valve Cleaner? Manufacturer on the can recommends vacuum brake booster line to spray into.

 

[wjburken]

I am trying to fix the issues on my own. @Bob2C had some success with his truck and CRC GDI cleaner. I found a thread on the gm-trucks and they recommend using this line here: https://www.gm-trucks.com/forums/uploads/monthly_03_2016/post-129450-0-16852400-1458543187.jpg

Any advice from anyone on that place to spray CRC GDI Intake Valve Cleaner? Manufacturer on the can recommends vacuum brake booster line to spray into.

I’ve heard of going through the brake booster line but I’m skeptical of how well that gets the cleaner to all the valves that are upstream of where the vacuum line connects to the intake manifold. I have used the Seamfoam product with a throttle body adapter for the can. Here is a link to what that’s all about.

 

[smokey_mountain]

Looks like my link did not work for what they are trying to do https://www.gm-trucks.com/forums/topic/184906-crc-gdi-valve-cleaner-spray/#comments

 

[BG1988]

Dmitry, are you saying that your catalytic converters are up over 1200 degrees after idling for say 20-30 minutes after the engine has reached temperature?

I have sat in a passenger seat and watched my cats before. Accelerating on the highway they easily climb up to the 1500s and then begin to slowly cool and at around 70 mph settle into the 1200-1300s on level ground. They'll quickly heat up going over a hill (bridge) and then begin to slowly cool down again.

Myself and @kbuskill have talked about cat temps before and posted our findings somewhere on this here forum.

checked ascending 2000ft Cat temps ranged from 350C to 680C mostly 550-590C

Decending 2,000 ft air temp 31-33F 140C to 633C @ 50mph quick peak temperature

140C@ 35mph @ 37F


(mostly 140-400C range )



everything was reading 0 values on the cat and fuel trims....etc.. the engine was running and @.35mph... when the cat drop to 140C..


no pending or 131/420/430 code..


just a sloppy guess honestly i kinda surprised as a California certified models have Tighter threshold...

 

[swathdiver]

checked ascending 2000ft Cat temps ranged from 350C to 680C mostly 550-590C

Decending 2,000 ft air temp 31-33F 140C to 633C @ 50mph quick peak temperature

140C@ 35mph @ 37F


(mostly 140-400C range )



everything was reading 0 values on the cat and fuel trims....etc.. the engine was running and @.35mph... when the cat drop to 140C..


no pending or 131/420/430 code..


just a sloppy guess honestly i kinda surprised as a California certified models have Tighter threshold...

Mine has/had California Emissions too.