LQ4 with 04 computer timing issue
Thread Starter
Teching In
Joined: Dec 2011
Posts: 48
Likes: 3
From: Dimondale, MI
LQ4 with 04 computer timing issue Hi,
I have a LQ4 with a cam (224/228 @050 571 lift), LS3 heads and LS3 stock intake and injectors. The rotating assembly is rebuilt stock LQ4. The trans is a 4L80 with a 9.5 inch 3000 stahl converter. The throttle body is a 92 mm cable Holley. I got the computer for a normal IAC, not a drive by wire. The starting cal is a 04 6L truck. For normal driving, the car runs, shifts great. The problem I have is that when I mat the pedal, the car takes off and then for some reason, the computer starts pulling out all the timing. As you can guess, the car then falls on it's face. I have looked at the spark removed from knock and it is always 0. I thought the PCM may be trying to torque limit to protect the trans. All the torque values in the cal have been maxed out at 640 if I remember right. I initially had some misfire counts at idle, but changed the RPM at which it ran the test and that eliminated the problem. The reason I bring this up as I was reading the post about converter lock up and issues with misfire. Will misfire take all the advance out to protect the engine, or maybe the cat that would have been there stock? The other thing is that the initial cal is a drive by wire that is modified for the IAC throttle body. The IAC does correctly control idle and works fine. There are no DTCs set.
Mike
I have a LQ4 with a cam (224/228 @050 571 lift), LS3 heads and LS3 stock intake and injectors. The rotating assembly is rebuilt stock LQ4. The trans is a 4L80 with a 9.5 inch 3000 stahl converter. The throttle body is a 92 mm cable Holley. I got the computer for a normal IAC, not a drive by wire. The starting cal is a 04 6L truck. For normal driving, the car runs, shifts great. The problem I have is that when I mat the pedal, the car takes off and then for some reason, the computer starts pulling out all the timing. As you can guess, the car then falls on it's face. I have looked at the spark removed from knock and it is always 0. I thought the PCM may be trying to torque limit to protect the trans. All the torque values in the cal have been maxed out at 640 if I remember right. I initially had some misfire counts at idle, but changed the RPM at which it ran the test and that eliminated the problem. The reason I bring this up as I was reading the post about converter lock up and issues with misfire. Will misfire take all the advance out to protect the engine, or maybe the cat that would have been there stock? The other thing is that the initial cal is a drive by wire that is modified for the IAC throttle body. The IAC does correctly control idle and works fine. There are no DTCs set.
Mike
I don't know the exact term, but you need to load up ( in the scanner ) all Spark & torque reduction tables due to Torque management as well.
Torque Management -> General -> Spark retard vs Torque reduction.
As well as removing any ( or properly tuning in) Torque management. Seen lots of cars pull timing but not be knocking. They were makin too much power =) Gl. Post a log or a tune if you need more help.
Torque Management -> General -> Spark retard vs Torque reduction.
As well as removing any ( or properly tuning in) Torque management. Seen lots of cars pull timing but not be knocking. They were makin too much power =) Gl. Post a log or a tune if you need more help.
