HELP! 548whp and low speed issues
02-22-2007, 07:11 AM
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HELP! 548whp and low speed issues I have the LS2 Edit; my car is a 2007 Z06 tuned at 548whp SAE with filter, headers with cats and cam.
When I accelerate in a traffic jam to just move the car forward and depress the clutch to brake, the rpms go as high as 1700 then come back down to the set idle of 950rpm.
If I am either cruising or coasting under 2000 rpm the car make oscillating pulls.
I AutoTap it and the only thing weird I saw is during the pulls the timing jumps quickly from thirty-something to the teens back and forth. I also noticed the TPS never goes to less than 18% (I think this is normal) am I right?
I would really appreciate if someone could tell me the parameters to change with the LS2 Edit to fix this, I have read of people fixing this with other programs like HP Tuners and EFI Life.
Thanks in advance
F Alonso
When I accelerate in a traffic jam to just move the car forward and depress the clutch to brake, the rpms go as high as 1700 then come back down to the set idle of 950rpm.
If I am either cruising or coasting under 2000 rpm the car make oscillating pulls.
I AutoTap it and the only thing weird I saw is during the pulls the timing jumps quickly from thirty-something to the teens back and forth. I also noticed the TPS never goes to less than 18% (I think this is normal) am I right?
I would really appreciate if someone could tell me the parameters to change with the LS2 Edit to fix this, I have read of people fixing this with other programs like HP Tuners and EFI Life.
Thanks in advance
F Alonso
02-22-2007, 07:37 AM
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You need to log your short term and long term idle trims to dial in the base running (aka desired idle) airflow table as a first step. The timing is most likely the cause of the low-speed surging. You need to command one value in the base spark table in the area you're seeing the surgning. The trick is to adjust the timing for decel without affecting the timing at idle. The trick I'm experimenting with to avoid idle timing issues is to alter the Base Spark theshold (speed at which the PCM will switch from the Base Spark to the High/Low Octane tables). From the factory it was set to only pay attention to TP% on my car. So, I just lowered the threshold so that when the car is above 7mph, it's in the High/Low spark tables. Then, I could command 41* of timing for <=0.24 grams/cyl and 2000-1200rpms.
02-22-2007, 08:14 AM
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Originally Posted by SSpdDmon
You need to log your short term and long term idle trims to dial in the base running (aka desired idle) airflow table as a first step. The timing is most likely the cause of the low-speed surging. You need to command one value in the base spark table in the area you're seeing the surgning. The trick is to adjust the timing for decel without affecting the timing at idle. The trick I'm experimenting with to avoid idle timing issues is to alter the Base Spark theshold (speed at which the PCM will switch from the Base Spark to the High/Low Octane tables). From the factory it was set to only pay attention to TP% on my car. So, I just lowered the threshold so that when the car is above 7mph, it's in the High/Low spark tables. Then, I could command 41* of timing for <=0.24 grams/cyl and 2000-1200rpms.
Here's a little info on how it works with LS2/LS7's
http://www.hptuners.com/forum/showpo...18&postcount=4
02-22-2007, 08:55 AM
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Originally Posted by foff667
Idle airflow is completely different from what your used to on LS1's
Here's a little info on how it works with LS2/LS7's
http://www.hptuners.com/forum/showpo...18&postcount=4
Here's a little info on how it works with LS2/LS7's
http://www.hptuners.com/forum/showpo...18&postcount=4
Still, with his timing jumping around the way it is, it can't be helping matters much.
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02-22-2007, 09:47 AM
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Originally Posted by foff667
Thats why I didn't comment on timing or idle in general just idle airflow 
