LS1_Dragster
June 21st, 2009, 07:26 AM
I have a '98 L-29 454 with a ZZ502 cam and ported heads using the 0411 computer with 01270003 OS, vic jr intake with holley throttle body and I have some questions regarding the B3702 Injection timing.
I've tried off and on the past few months when I get time to tune this in the garage before it's first road trip and I've had a terrible time getting rid of an exhaust backfire when zinging the throttle quickly. Logic told me that it's either rich, bad valve or an ignition problem so I eliminated the last two items and started looking at the way the injectors are firing.
I figure that with the larger cam the exhaust/intake timing event has changed enough that maybe the fuel is being injected while the exhaust port is still open so I messed with the B3702 and added 20% to all the values and the exhaust pop was instantly gone! Also, the WB showed a lot richer at idle so I had to reduce the idle MAP by 3% and also the idle average jumped 150RPM. Why would I have to mess with that? And is adding 20% advancing or retarding the injection event? Is this just band-aid solution to a problem elsewhere?
Lee
I've tried off and on the past few months when I get time to tune this in the garage before it's first road trip and I've had a terrible time getting rid of an exhaust backfire when zinging the throttle quickly. Logic told me that it's either rich, bad valve or an ignition problem so I eliminated the last two items and started looking at the way the injectors are firing.
I figure that with the larger cam the exhaust/intake timing event has changed enough that maybe the fuel is being injected while the exhaust port is still open so I messed with the B3702 and added 20% to all the values and the exhaust pop was instantly gone! Also, the WB showed a lot richer at idle so I had to reduce the idle MAP by 3% and also the idle average jumped 150RPM. Why would I have to mess with that? And is adding 20% advancing or retarding the injection event? Is this just band-aid solution to a problem elsewhere?
Lee