5.3 Swap funky start up idle

[scoop524]

Startup Idle spikes to almost 3000 rpm
Cold idle seems fine but after that it takes a crap.
Any help appreciated!
Cheers Scoop

[GHuggins]

Is the tb original and the mate to the ecu? Is the engine from a same yr model truck? It's most likely the tb not being right for the ecu/tac module, because that's exactly what they do. If it's an electronic TB...

[5FDP]

The MAP sensor is not reading correctly before the engine starts. It starts at 67kpa and goes to 72kpa while cranking. The key on engine off should be roughly 100kpa at sea level.

Your VE table is crazy rich, why did you add like over 90% worth of fuel in nearly all of it. Is your fuel pressure correct?

The over/underspeed spark correction tables are the same. One has to be -8, so go back and look at which one was negative before you made that change.

You didn't say if this was modded but your base running airflow is alot higher than stock from the looks of it.



The data log is missing lots of stuff and I noticed you turned off all the o2 sensor codes from the upstream sensor. Are you not running them?

[scoop524]

Is the tb original and the mate to the ecu? Is the engine from a same yr model truck? It's most likely the tb not being right for the ecu/tac module, because that's exactly what they do. If it's an electronic TB...

The TB and ECU are from different truck but same year and same OS. Cable TB.
Thanks

[scoop524]

The MAP sensor is not reading correctly before the engine starts. It starts at 67kpa and goes to 72kpa while cranking. The key on engine off should be roughly 100kpa at sea level.

Your VE table is crazy rich, why did you add like over 90% worth of fuel in nearly all of it. Is your fuel pressure correct?

The over/underspeed spark correction tables are the same. One has to be -8, so go back and look at which one was negative before you made that change.

You didn't say if this was modded but your base running airflow is alot higher than stock from the looks of it.



The data log is missing lots of stuff and I noticed you turned off all the o2 sensor codes from the upstream sensor. Are you not running them?

Thanks will try a different MAP sensor.
VE table has been corrected, wow crazy rich as you stated.
Fuel pressure has been monitored and is ok.
Sloppy stage 2 cam and headers
Just using post O2 sensors as no cats, complete exhaust
Thanks Scoop

[blindsquirrel]

The downstream O2s only work as catalyst monitoring, they can't be used to control fuel. Only the upstream sensors can do that.

[scoop524]

The downstream O2s only work as catalyst monitoring, they can't be used to control fuel. Only the upstream sensors can do that.

Thanks Change made
Scoop