At the Dyno my A/F reading was 11.2. This did not occur throughout the run. This only occurred around 3200-4500 RPM. When I am driving around town if I punch the gas I get what sounds like detonation inside the exhaust pipes. Are these two problems related. This started occurring following the following mods which were done at the same time: SLP 1 5/8" headers, 3" Random Technology catback, Crane AFPR, underdrive pulleys. See sig for additional mods. What could be causing this and how can I get rid of it? Chip?

 

the detonation sound in the pipes is probably from a leaky header gasket or other exaust leak. The fresh air causes the mixture to burn when it encounters fresh air. Mine does the popping in the primaries as well because the air is encountering a rich hot mixture of exaust and causing it to combust, except it does that crap all the time. Have the stock chip and its rich all over except for around 3k where it starts to go lean. I wouldnt worry too much about it slipping into the 11.2 range. Try to get it up a little if possible.

 

Could a faulty ignition coil or anything else with the ignition system cause this problem or would a ignition problem cause this problem all the time and not just at a certain RPM range?