GL1800 intake & exhaust

[haddont]

I tried to find something about this in a thread and maybe didn't use the correct search phrase. Anyway, please bear with me.
I have recently added a Kury air filter and iridium spark plugs to my engine. Then I added Torque Loops and V&H Monster mufflers. I'm happy with the changes but I don't feel like the computer has adjusted to the changes very well. I get a bit of backfiring when I decelerate and my gas mileage has dropped from a pretty steady 33mpg to 28-30 mpg. Is it possible I may have a busted O2sensor or something? I'm not very mechanically minded but it seems like these changes should have helped my gas mileage, not hurt it. I did gain a very noticeable amount of power with the changes but I don't want to damage my engine.
Has anybody got any ideas on what, if anything, I can do about this? To me, the small backfires are embarrassing as I consider it an indication of an ill-tuned engine.

[Gold Rush]

Two thoughts....

First, have you tried the ECU calibration. From full cold start the engine but never touch the throttle. When the engine reaches full operating temperature shut it off and restart. In all honesty, I don't think that will fix your issue.

My second thought is a fuel system management system. I don't know if one is available for the GL1800 but I expect your fuel/air mix ratio is way off. One of the effects of major exhaust changes......

I hope that helps

[msocko3]

If you would have a broken O2 sensor I would think it would throw a code. The trouble with fiddling with increasing the ability of an engine to take in more air through a more efficient air cleaner and exhaust can cause some issues. The factory ECM will only compensate so far for the changes, this can lead to lean and even rich spots. To the best of my knowledge there is no tuners on the market for the GL1800 at this time. I have heard rumors Dynojet is working on one, don't know when it will be to market if ever.