At the risk of my neck, consider a few more things. First, the BHR coils do not have the same dwell (~5 msec) as the stock coils (~3 msec). Without changing the dwell tables (as yet impossible to do with the Series II cars), they will not be making the power they are capable of, nor, quite possibly, make as much power in certain ranges as the stock coils with the stock dwell settings. Some report longer start times with the BHR and stock dwell, since even with a modded dwell table in the Series I, the starting dwell times are not not adjustable with Race Tuner. I noticed a lot of the idle burble I had went away when I changed the dwell tables to match the BHR coils. Second, you have modded the car somewhat with the exhaust and K&N. While it seems like a small change, in principal, without a change to the tune, there will be changes in the AFR's through the rpm range as a result. I have noticed that well-maintained dead-stock cars do seem to idle more smoothly than modded ones. MM tunes increase the idle rpm slightly to get a smoother idle. Also, I've noticed my idle improves on those rare occasions when I can fill with no ethanol fuel.

I'd suggest that your experience is normal for this car, differing only in that you're picky about getting a silky smooth idle. It may also be in your driving profile, that the stock pig-rich mixtures during acceleration are slightly fouling the plugs more rapidly than others experience.



YMMV.

 

Ok thank you .... a lot of that made sense, appreciate that. We actually changed the dwell tables when i had this thing running on the haltech for a short period of time but we had to return it to stock because of some issues we ran into. That did improve it a lot from what i recall . Thanks again for the info,

B

 

YW. There's a little experiment you can do if you like. Somewhere I read that in steady Closed Loop operation, the feedback from the front O2 sensor is not targeted directly at Lambda = 1.00, but alternately a little high, then a little low, like 0.98 - 1.02 - 0.98 - 1.02, etc. This keeps the feedback loop "alive" and avoids math errors that can occur with 'divide by zero' events. If you're on an edge this oscillation may generate occasional misfires. When I force my car into Open Loop using the AccessPort, I have the impression that it idles and runs smoother at low rpm. You could force OL by disconnecting the front O2 sensor and see if that makes a change in smoothness. It won't solve the problem long term since you don't want to leave it disconnected, nor run with a CEL, but it would be interesting to see. (The rear O2 sensor also provides feedback to the system - but no one seems to know exactly how that works.)