Can't nail startup RAF
02-10-2006, 08:48 AM
#1
Can't nail startup RAF Maybe I'm going about it the wrong way.
My long term idle trims are pretty close to 0% and my short term idle trims look good except for startups...especially hot re-starts.
My short term idle trims are in the +2 g/sec at hot restart even though my LTIT are low. What affects this more? Idle Airflow Parked Position {B4308}? Startup idle airflow correction {B4303}? Startup Friction Airflow Correction {B4343}? FWIW, my values are raised above stock for B4308 and B4303.
Does the positive number mean I'm not getting enough airflow and the PCM is needing to add more? Thanks in advance.
My long term idle trims are pretty close to 0% and my short term idle trims look good except for startups...especially hot re-starts.
My short term idle trims are in the +2 g/sec at hot restart even though my LTIT are low. What affects this more? Idle Airflow Parked Position {B4308}? Startup idle airflow correction {B4303}? Startup Friction Airflow Correction {B4343}? FWIW, my values are raised above stock for B4308 and B4303.
Does the positive number mean I'm not getting enough airflow and the PCM is needing to add more? Thanks in advance.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2018 Cadillac Escalade 6.2L A10 Pat G tuned.
LS1,LS2,LS3,LS7,LT1 Custom Camshaft Specialist For custom camshaft help press here.
Custom LSX tuning in person or via email press here.
02-12-2006, 11:17 AM
#5
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Mine does the same thing. The value is coming from the Startup Friction Airflow Correction {B4343} table. As soon as this value zeros out it is transferred to the short term idle trim in drive and park/neutral. Leaving the car in park it takes the short term idle trim about 30s to return to “normal”. When I put the car in drive the IAC numbers and idle jump up responding to the high number in the short term idle trim and within 30s the short term idle trim return to “normal”. All is good until I turn the car off and restart it.
John
John
Last edited by JNorris; 02-12-2006 at 11:24 AM.
02-12-2006, 11:57 AM
#6
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Have you tried adjusting the decay and delay rates for the Friction Airflow Correction? I changed mine and this seemed to help on both hot and cold start ups.
02-12-2006, 12:10 PM
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I have played with the decay rate. The issue is after the Friction Airflow Correction value has decayed to zero the original Friction Airflow Correction value is placed in short term idle trim for drive and P/N.
