help! 383 stumble putting in gear...got some Tech II scanner info included
 

hey guys....

just got my new forged daily driver 383 setup on the road and am looking for any ideas of what might be causing a stumble just after putting it in gear. i've got a very mild cam in it for a 383 so i don't think i should be having the issue i'm having and am hoping somebody might can give me some suggestions on what might be causing it. i have already increased my idle by 100 rpm's in the pcm to 850/825 (park/gear) but doesn't really seem to help and from what i've read, i should be able to idle at those numbers pretty easily with my setup.

basically, when i drop it in gear from park, it stumbles and almost acts like it wants to cut off for a bit. if i give it time to settle down, it ends up idling pretty decent, but then if go back to park and in gear again, it stumbles again. from what i can tell, it's much worse after a cold start than it is when it's good and warmed up. but i still think there must be some adjustment that needs to be made because it acts much worse than i believe it should with the relatively mild setup i have....just doesn't seem to like the transition from park to in-gear at all. i put a Tech II scanner on it this weekend and thought i would include some stats i jotted down after it had warmed up and was idling. i don't really know what they mean, but maybe they will give somebody a clue.

Throttle position - 0.60 volts
Throttle angle - 0
BARO - 5.00 volts
BARO - 103 kPa
IAC Position - 46 counts
Learned IAC - 47 counts
Spark Advance - 28 - 31 degrees (varies between there)
Short term FT Bank 1 - 137 counts
Long term FT Bank 1 - 160 counts
Short term FT Bank 2 - 143 counts
Long term FT Bank 2 - 160 counts
Fuel trim cell - 16
MAF Sensor - 7.5 gls
Injector PWM Bank 1 - 3.0 ms
Injector PWM Bank 2 - 3.0 ms
KS activity - 12 counts
MAP - 1.96 volts
MAP - 44-47 kPa (varies between there)

my mechanic said that it smells like it is defiantely running rich to him, and from the little i know about it, it does to me too. i wouldn't think that this would be causing my stumble, but wanted to throw it out there just in case. in a previous thread, "TQdrivenws6" had suggested that i check my IAC counts and TPS voltage at hot closed loop idle, but according to him, it looks like my IAC counts are right about where they should be. he was having a similar problem and found that his IAC counts were pegged at 160 and the engine wasn't getting enough air to stay alive.

thanks in advance!

robert

Re: help! 383 stumble putting in gear...got some Tech II scanner info included
 

The 160 IAC means the IAC couldnt open any further to meet the air demands of the motor which is why it died.

THe Long term values are also maxed out at 160. The computer thinks the motor is running lean and dumping in as much fuel as it possibly can to compensate. The question is... is it actually lean or is there another reason like a large vacuum leak after the MAF sensor.

Re: help! 383 stumble putting in gear...got some Tech II scanner info included
 

turbo,

how could I check for such a vacuum leak?

i have checked the rubber elbow coming off of the TB for a good seal and at one point over the weekend actually found where it wasn't sealed up good at the point where it connects to the MAF. i thought i had possibly found the issue when i found that, but even after fixed that, it didn't seem to matter.

Re: help! 383 stumble putting in gear...got some Tech II scanner info included
 

Just crank on the idle screw until it idles. Mine idles a 1200 in neutral but who cares it's what it does in gear and the air on.
Set the parking brake,turn on the air,put in D and set it where it will idle by opening the blades with the idle screw. Take it out and drive it to let it learn then reset idle if it's to much.