SSlow 4.8

iTrader: (4)

Car is a LME 408 iron block
Trick flow 215 heads
Cam motion 244/250 .643/.645 112lsa
12:1
Fast 90/90
nick williams 90mm tb
slp 85mm maf
255lph walbro
42# inj and 61psi fuel pressure
Kooks 1 7/8" headers
th350 trans



here is the thread from hptuners w/ the idle file attached.
http://www.hptuners.com/forum/showthread.php?t=24630

they arent chiming in over there and i need help w/ this.

I modifed airflow tables, cracker, follower, played w/ idle timing/fuel. Cant seem to get it right.

It'll cold start decent, surge and die. If i play w/ the throttle it'll run. But then sometimes it will idle great for 5 minutes and suddenly hunt for the idle again and fall on its face. When putting it into gear hot or cold, dies.

Car has zero miles on this build, try to see if maybe it just needs to learn the idle longer. Owner wont take the car out w/ it surging like this. Im pretty confident i can two-foot it.. but its his baby.

If you want the file i can send it, but its on that hptuners link.

thanks!

SSlow 4.8

iTrader: (4)

ttt...

Frost

iTrader: (45)

Here's what I see:

VE is not tuned, changes made, but not tuned
MAF curve is stock
Idle Airflow is set VERY high.. should tune it rather than trying to open up LTIT limits
startup airflow is very high
Many changes to PID idle control were made before VE and idle airflow were established, they need to go back to stock until the VE and idle airflow are correct
All short pulse and offset table(s) for the injectors are still at OEM values.
Commanded idle values are too wide to cover with the IAC, cold/hot need to be closer together.

finish the injectors, un-do the PID changes, tune the VE, tune the MAF, do the idle airflow tuning

Mike454SS

iTrader: (4)

Steve, do you ever play much with the PID control itself? Do you have a method? I spent the better part of last week trying to hunt a surging idle on a big cam in a friends car with a stock 346 bottom end. I've gotten it idling decently with the idle airflow, VE and MAF tables dialed in...as well as the cooling fan airflow numbers...but once in a while it still surges a bit more, and it makes drivng it a little less than pleasant.

Frost

iTrader: (45)

Once everything I mentioned above is right, it is VERY seldom that I have to tune the on the PID side... Once in a blue moon I will need to slow it down a shade or reduce it's response level but it is really is not often. Does your car do it in SD mode also?

SSlow 4.8

iTrader: (4)

alrighty.. thanks for the response Frost! Helped me once again. I also refered to Krambo's idle tuning.

Check this out, i'll attach it if i can. If not i can email it to you frost but it idles really good now.

Im not sure if i corrected PID in everything that i changed OR if i even addressed the injectors... can you point me in the right direction on that?

But i went back to stock to start over with all this.. bc that tune is a damned hack job. idk who messed with it but that base airflow was like 10-11g/sec too high. Its really still too high, but i'll calm it down once im done.

Can you help me with the short pulse and offset tables when you get a free minute. I just need to locate them and figure out which direction they need to go (42# inj w/ 61psi fuel pressure if that helps).

Oh and the reason why VE is played w/ and not tuned for is because of a couple reasons. One; it was so badly idling that we were scared to drive it around bc it would die in gear etc and two; we cant really drive it like i want
anyway bc of the lack of tag and insurance, lol.

thanks Frost

SSlow 4.8

iTrader: (4)

can a mod delete this please?