WS6FirebirdTA00

iTrader: (33)

all i did was change the idle timing and now on start up the rpms shoot up to about 2k, hover there for a second and then go down. is this timing related or do i need to change something else now that i am getting the timing i shoudl be?

TXCAMSS

iTrader: (60)

I have noticed that bumping the base idle timing DOES create an over shoot and delayed drop. I can't tell you why, but that symptom is a result of too high of a base timing addition.

I guess it's good for some and bad for others.

WS6FirebirdTA00

iTrader: (33)

ill try to knock it down and see what that does to it, with the gas here, ill wait on that lol noone is gonna get my money becuase they are greedy bastards

WS6FirebirdTA00

iTrader: (33)

well i took out about 5* on start up and its still hanging on me, maybe i should pull some timing from the start up correction in the higher g/cyl and see if that helps? i took out 5* and only added about 7 so i dont know. any ideas would be nice, i havent really messed with any start up parameters after the cam install besides the timing on start up which i just mentioned

Buckshot

I had this problem on mainly cold starts on my C5 a couple of different times on my initial tune a couple years ago and recently after some other changes. I pulled my IAC (idle airflow table - gm/sec vs. ECT) down in the 8-68 deg. C section down until the cold-start settled down. Mine is an MN6 so I only needed to tweak the In-gear table. An auto may need the Park/Neutral table adjusted.

WS6FirebirdTA00

iTrader: (33)

well my idle airflow tables are set up right based on the trims. this just happened after timing changes but i pulled more timing on start up do i dont know what gives

Purrvert

There are calc formulas in EFILive, check their web site, to tweak your airflow at idle, RPM vs ECT. Tamed my idle, stopped low RPM stumbling, dying at will, allowed me to close the 3/32" hole drilled.
Hell, I think it even grew hair.

WS6FirebirdTA00

iTrader: (33)

guys, i dont have any problems with idle, it is ONLY start up rpms, i turn the key, rpms go to about 1800 and hang sometimes for a second and then come back down and are fine. that is all i need to fix. the idle airflow is set perfectly from 20*c and up, trust me i know a lot more than you will ever want to know about idle tuning seeing the last year that has been about 80% of all my logs/tunes.

i just need to get this start up under controll, i guess ill just go to my logs and tyr some things out until someone can come up with more ideas

Purrvert

Check B4512, here's the explanation.
"Airflow correction to be applied based on RPM rate of change which tries to dampen overshoot of desired RPM.
If RPM is increasing the value in this calibration is subtracted from the desired airflow,If RPM is decreasing the value in this calibration is added to the desired airflow.

The "rate of change" of the engine RPM is a ratio of two, filtered rpm followers. One is weakly filtered and tracks the rpm closely, the other is strongly filtered and lags the rpm.
"Rate of change" values closer to zero indicate that the engine speed is changing slowly.
"Rate of change" values closer to 0.15 indicate that the engine speed is changing quickly."
Also take a peek at B4515.
Good luck

TXCAMSS

iTrader: (60)

I wonder what B4512 is in HPTuners? I think that's what he has.

That sure sounds like the culprit and also a very usable table.

Good info, Thanks!

Purrvert

May be Throttle Follower on the Idle Airflow page. Make small % changes in the affected RPM area.

Slowhawk

iTrader: (12)

Sounds like the start up is too lean.I would add some fuel in the VE table and lower the IAC table.

WS6FirebirdTA00

iTrader: (33)

what i did was increased the startup flare to account for the extra 8* of timing i have at start up. i will see if that will help when i start up today, if not ill look into other things. i would think this would fix it though seeing this ONLY happened after i added timing. thanks guys

WS6FirebirdTA00

iTrader: (33)

looks like increasing spark dwell worked out, now i need to pull more timing from the start up correction so when i tap on the gas the rpms wont hang then too.