Well, at first, i couldnt have a conversation in my truck at highway speeds because the exhaust was too loud - swapped the flows and put on magnaflows. great move - love the sound - hella quieter on the highway.

Then i decided to get a lightning sized upper pulley - swapped that out, now my truck sounds funny and i am getting detonation at higher rpms. also, one of my O2 sensors has already crapped out after 16K+ miles.

Can anyone help?

 

I have not had that type of problem on my truck, but I can point you to a few directions.

1) Plug a code reader to determine if there are any codes that the computer is recording.
2. How much boost are you getting? How are your A/F readings?
3. I think you had your chip already burned to a certain program and then swapped the upper pulley. Your program might not be the best tune for your current setup now, it could have been the best before the upper pulley swap.
4. Although the noises are sometimes hard to distinguish, sometimes it could be the S/C with too much rpms.

Hope this helps in your troubleshooting.

 

why would my supercharger be over -revving if it just has a lightning sized pulley on it (for a 2 lb increase in boost)?

 

Again, I'm not an expert on this subject. Depending on your chip program, whether the rev limiter has been totally removed or moved up on the rpm range, or your shift points bumped up higher may contribute to what you are experiencing. The later your shift point are, the higher the rpms on your engine and S/C. You mention that you are getting detonation on 'higher rpms' so it sounds logical to check those areas.

Also, did you change belts when you did the pulley swap? The L upper is smaller in diameter than stock(correct me if I'm wrong), so you may need a shorter belt. Not sure if it is related, but it's safer to double check.

 

the belt stayed the same - the tensioner provided more than enough - and as far as i know, the belts are the same on both the harley and the lightning.

 

Did you reburn your chip for the changes? Change in exhaust and 2lbs, you should. If you can hear the detonation, you're only hearing part of it. You need to follow up on that or risk toasting your motor.

 

Your chip definitley needs to be reburned. I would aslo recommend dyno tuning to acheive an A/F less than 12