Thread: Custom Tune Installed
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Old Mon, June 8th, 2009, 07:56 PM
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Jackpine Jackpine is offline
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Originally Posted by DarrenWS6 View Post
Well let me better explain the idle issue. Coming to a stop at a slow speed ( 30mph to 5mph ) basically approaching a red light or stop sign, from the Gryphon readout it drops down to near 480 then varies in the low 500 - high 500, then acceleration is perfect, but it seems quite low for an idle in gear. I tried raising the idle before but it only let me increase it to 300rpm? Does that mean 300rpm overall? or 300rpm over the normal 600rpm? I dont understand how this works.

Thanks again Jack for the clarification, much appreciated
Good questions, Darren - don't stop asking them. I think you're seeing an RPM dip as you apply the brakes while you're still rolling? And, if this is the case, I've not seen it (probably because I haven't looked) and I don't have a clue if this is normal or not. Back in the bad old days we used to have a damper in the carburetor to prevent sudden drops like that (which could stall the engine).

However, it sounds like maybe your idle RPM is fairly normal (in the 600 range) when you are just sitting there stopped? And, when you step on the gas, everything increases normally? If this is the case, then I don't think there's anything to worry about.

About the only thing you need to worry about in the idle setting is: "Is it charging my battery?" If you see voltage (on the Gryphon, which I monitor) in the 13.5-14.0 volt range in idle with lights and accessories on, you're OK. Underdirive pulleys can reduce the alternator output and may require you to increase the idle speed. And, in case you wondered why I monitor voltage, it's because I sometimes pull a trailer with two batteries and a refrigerator on board. So, that's a pretty heavy electrical load.

The adjustment in idle in the Custom Options menu is plus or minus from the "baseline" RPM. So, if Bill set your idle RPM at 600, and you adjusted it to +100, you should see 700 RPM (approximately) when stopped. I say approximately, because I suspect the drag of the TC will have some effect on the final result.

- Jack