Extremely odd cold Startup

[ns158sl]

The truck is a 2000 Silverado
with a 212/212 112 cam
Heads shaved .020
Otherwise stock




Well I realized I was threadjacking so I figured I would start my own. I can't seem to figure out what is going on with my truck at startup. It seems to only have a problem at cold startup and when put into gear when still cold. I just installed a new cam and trying to get my Base Running inline. I have already tuned the VE table and MAF, and played with timing as well as idle timing and idle AFR. What happens is the truck will pull timing at idle when cold. I have logged as much as 30 degrees pulled. It does not knock, or throw a DTC. The timing retard is also TQ MGMT Retard which is really throwing me for a loop. I have zeroed out and maxed out a couple TQ MGMT tables and nothing changed. I finally 0'd the Spark Retard Vs. Torque Reduction, and it still seemed to idle extremely bad, and still was pulling timing but not as much. I'm wondering if I am missing something basic, or is there a table lurking somewhere that I am not able to tune. The first log is without the Spark Retard 0'd out. The Log labeled weird is the Spark Retard 0'd. Thanks a lot

Eric

[printmanjackson]

I don't think an engine likes much timing when cold. Why don't you try using the VCM controls and play with timing and fueling to see what it likes. Then find the tables that affect it in that temp range.

I have been cold start tuning for a while and it's a slow process. Not only di you get one chance a day but it seems the weather around here changes all the time too.

[ns158sl]

It definitely likes more timing. Its weird because i havnt found a tq mgmt table that is vs ect. Unless its another table that is affecting it and it isnt considered tq mgmt.

[printmanjackson]

go to: spark >advance>ECT spark base

this might be what's pulling spark advance when cold

[ns158sl]

Thats the weird part. If anything it should be adding timing based on that table. The other thing is when im logging, the pulled timing is comeing from tq mgmt spark advance PID.


Eric

[printmanjackson]

try zeroing out the torgue loss table:

Torq mang>general>torque loss% vs spark retard table

mine is zero

[ns158sl]

Thats what i did for the second log labeled weird. It seemed to not pull as much timing but still acted weird. Its also weird if I let the rpm stabilize before i put it into gear, that helps or if i blip the throttle then it seems not to retard the timing as much. It almost seems to be on a timer of some sort but my cat lightoff is zeroes plus i cant find a table that would pull 30as degrees at that ect.

Eric

[printmanjackson]

you got me .....

[ns158sl]

Lol i know right! Yah i guess thats why i had to start a thread because ive ran out of ideas. I appreciate the input though. I only found around one to two threads on here with the same problem but there was never a fix for it.

Eric

[ns158sl]

I guess now my thoughts are maybe for some reason something is triggering the ecm to have tg mgmt come into the picture and try to slow down the idle or try to reduce power, because it retards the timing and dam near enough to snuff out the engine ... Or some table that isnt unlocked maybe.

Eric

[ns158sl]

Well after some more zeroing tables I am back with another log showing no improvements.. It is the same thing as before. Cold start and put into gear while holding the brake. This time I held it a little longer and it actually surges as the timing comes up and down.

Eric

[gn2beatu]

Do you have a ported TB? The computer will pull timing if there is too much airflow to try and reduce the idle. I have seen as much as -14 degrees on an overported TB.

[ns158sl]

No its a stock tb but maybe my desired airflow is too high? Ill try reducing that and see what happens.

[ns158sl]

Well I tried a little lower RAF where I am having issues and it seems that nothing has changed... I don't know if I should email support and ask if there is a table that is somewhere lurking in the ecm for this issue or what. I can't believe I am the only one with this issue and with no resolution yet.

Eric

[printmanjackson]

contact Ed and see if he can help. He is here on the forum

EFI specialist
Advanced diagnostics, tuning, emissions
Tuning all GMs, Ford, Mopar, Nissan GT-Rs, Evos, WRXs, Euros
[email protected]

[ns158sl]

This seems odd. Im starting to wonder if its a transmission table that is affecting it? I already tried abuse mode and desired torque... Or it could be mechanical, but I doubt it. It only did it after upgrading to a cammed 5.3

Eric