start-up/idle issues...imagine that?

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08-19-2008, 07:39 AM
Superado

start-up/idle issues...imagine that?

start-up issues since new build install...
this is after ALOT of idle tuning...

LS1, Procharger P1SC, Patriot Stage III heads,
218/230 .605”/.604” 112LSA +3, longtubes

mornings...fires up on first turn over and usually catches itself and idles...
however, after several minutes of warming up @ idle, putting it in gear its fine but usually cuts off when I turn the wheel to exit the driveway...

rest of the day it MAY fire up on first turn over but will not catch itself and idle...
sometimes on the 3rd or 4th attempt it will catch if I don't decide to go ahead and pedal it...

if I pedal it for a little while, it idles fine...still wants to cut off when I start to leave the parking space though...this is after noticeably going into closed loop...

once I'm on the road...its all good...morning, noon or night...

tried adding more air at start-up...worked for a day or so...
tried adding a couple seconds to delay @ start-up...worked for a few starts, then right back to same issues after driving 15-20 minutes, parking and attempting to restart about 30 minutes later...

only SES code active is TPS performance range...I assume this is due to idle screw adjustments made during idle tuning...could this also be my catching @ start-up issue as well?

what specifically to I need to be looking at?
thanks in advance!
08-19-2008, 02:29 PM
Superado

also...
As of yesterday...I have a hesitation @ WOT...meaning...
when I mash the pedal to the floor...instead of it going WOT, it hesitates for a couple seconds...then goes WOT...
This has never happened before...where should I look?
08-19-2008, 03:19 PM
RedHeartbeat

TPS, MAP sensor and wiring or fuel pressure
08-20-2008, 09:43 PM
ChevyLee

What fuel pump do you use? As Greg said check fuel pressure. My truck wouldn't start on the first try similar to yours, because the fuel pump wasn't holding pressure.
08-21-2008, 05:27 PM
Superado

made the following changes this afternoon...found on efilive forum...so far...so good

Quote:

Increased the Startup Friction Airflow Correction table for better starts. Although this doesn't really have to do with idle swing, I thought I'd include it because it seems to be a common problem. I increased this table by 4 grams/second across the board. Now, my warm start issues are gone. It was stumbling right after startup, barely running because there wasn't enough initial airflow. Adding air in here is a good, temporary way to add in the airflow, which will be decayed out after the first 30 seconds or so.

Quote:

Changed the Learned Airflow Correction table by zeroing out the 0-20 absolute rpm cells. This means the car won't correct the learned airflow values (STITs/LTITs) until it's more than 20 rpms above/below desired idle speeds. With cam'd cars that have a choppier idle, the STIT/LTIT settings can be too aggressive. This softens them up a little.

Quote:

Changed the Direct Airflow Correction table for High and Low RPM scenarios (Drive, A/C on, etc.). IMO, this was also making very aggressive airflow corrections. By zeroing out the 0-40rpm cells and reducing the remaining cells, I was able to prevent the idle from over-correcting and swinging up & down.
08-22-2008, 09:07 AM
SCIV

Not related, but Super how much boost are you going to try and run with the P1?
08-22-2008, 10:15 PM
Superado

Quote:

Originally Posted by SCIV

Not related, but Super how much boost are you going to try and run with the P1?

was running 10+ #'s on the stock 5.3L w/ the 4.0" pulley...
on the new, forged, lower compression motor w/ the 3.40" pulley it seems that it is going to be about 10 #'s again...maybe a bit more when I get this tune dialed in better...