2004 6.0 NV4500 Tahoe

[Dantheman1540]

Ok @randeez I need help.

Since I switch cams I've had a weird issue whereupon startup the truck runs crazy lean for a good solid minute. It doesn't matter whether it's idling or driving it runs crazy crazy lean and I can't seem to find any solution. I've search HPtforum and posted on PT.net but no luck so far.

Well, I was gonna post logs on here but idk how to.

 

[randeez]

what os? P01?

i pm'd you my email address, dont know the tables off the top of my head.

does it run bad? or you just see it in the log?

 

[Dantheman1540]

what os? P01?

i pm'd you my email address, dont know the tables off the top of my head.

does it run bad? or you just see it in the log?

Email sent to [email protected] I hope you get it.

Anyway yes at startup when it's running super lean it drives like crap and will sometimes get jerky and then fix itself seconds lager and drive totally fine. It doesn't matter if its a warm or cold startup.

 

[pwtr02ss]

Email sent to [email protected] I hope you get it.

Anyway yes at startup when it's running super lean it drives like crap and will sometimes get jerky and then fix itself seconds lager and drive totally fine. It doesn't matter if its a warm or cold startup.

I thought his email was [email protected] ? Now I know why I only got nudes when I needed help with my “going fat at WOT” email...tuning advice is a totally different address.

anywho, have you cleaned the maf and Tb? False readings up front can lead to dry or wet tailpipe

 

[Dantheman1540]

I thought his email was [email protected] ? Now I know why I only got nudes when I needed help with my “going fat at WOT” email...tuning advice is a totally different address.

anywho, have you cleaned the maf and Tb? False readings up front can lead to dry or wet tailpipe

Oh you are silly! Had me nearly spit my smoothie

 

[randeez]

did you recently clear/reset the fuel trims or something?

not sure if all the channels youre scanning are coming across right to me, but also log whether its in closed loop mode or not. if BIG IF the VE table is right and its doing it im not sure what table to use to correct it...would usually be something like "startup/runtime vs ect" and you can adjust what afr it targets after startup for a couple minutes - but your OS doesnt look like it has anything of that sort.
to me it looks like the VE tables are way off and it takes a while for it to enter closed loop, when it enters closed loop it takes care of it.

looking at engine>fuel>o2 sensor> ECT vs IAT table , you dont enter closed loop with 57* intake temp until coolant temp gets to 131*

 

[Dantheman1540]

did you recently clear/reset the fuel trims or something?

not sure if all the channels youre scanning are coming across right to me, but also log whether its in closed loop mode or not. if BIG IF the VE table is right and its doing it im not sure what table to use to correct it...would usually be something like "startup/runtime vs ect" and you can adjust what afr it targets after startup for a couple minutes - but your OS doesnt look like it has anything of that sort.
to me it looks like the VE tables are way off and it takes a while for it to enter closed loop, when it enters closed loop it takes care of it.

looking at engine>fuel>o2 sensor> ECT vs IAT table , you dont enter closed loop with 57* intake temp until coolant temp gets to 131*

I was looking at that how it doesn't go into CL until 131* I just never messed with that personally therefore I didn't think it was the problem but it's certainly something to try. I'll probably put it back into OL and do some VE adjusting again, it's been a while and I only tuner it in summer. The biggest PITA is I have to hook the truck up to a bench harness every time I make adjustments because it fails every damn time I try to load a tune without being plugged into a wall.

Referring to a stock Gen3 truck shows that table exactly that same having 131* before going into CL.

 

[randeez]

what i would do is start it up as it is, let it get up to temp. you can knock it out of closed loop with the "vehicle controls and special functions" button next to the engine diagnostics. leave it running and restart the log with it in open loop and see where the fuel trims are. wouldnt worry about the dfco being on that much just make sure its in open loop when you log to make changes to VE

 

[Dantheman1540]

what i would do is start it up as it is, let it get up to temp. you can knock it out of closed loop with the "vehicle controls and special functions" button next to the engine diagnostics. restart the log with it in open loop and see where the fuel trims are

Didn't know I could do that with the special functions button I'm gonna try a log now.

 

[Dantheman1540]

Sure as shit your right @randeez. got up to temp and it righted itself to 14.7, Commanded CL off and boom back to lean as fuh. Saw as high as 22afr . I guess I have some VE table tuning to do.