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Ross
06-06-2005, 06:58 AM
A year ago or so, I installed DR's UD pulleys. I like the results, but of course, the idle speed of the engine was lowered a little bit. That's not a problem, except when idling in hot weather with the AC running. The compressor needs a couple of hundred more RPM's to work properly and blow cold air at idle.
This has been discussed before, and it's a known phenomenon. I went through last summer with this situation, but I have decided to do something about it this summer. As you may know, summer lasts from early April to early November in Houston!
To me, the best way to increase the idle would be some sort of computer reflash, since everything is controlled electronically. In the old days, I would have just turned an idle screw on a carbuerator, but I am very hesitant to do that on such an electronically sensitive modern engine.
OK, here's the problem:
I have spoken to several local wrenches, including a Ford speed shop. The speed shop said to just adjust the idle mechanically by turning the screw. I'm still afraid to do it that way.
A couple of others said that the idle can't be adjusted through the computer.
What's the story? How have others who have UD pulleys handled this?
Also, if I can get a computer reflash, will that mess up the aftermarket chip that I have?

crom
06-06-2005, 07:03 AM
You should be able to have the chip reflashed with a higher idle setting. I have the xcal from DR and he sets the idle higher on his custom tune. This is for the undies just as you have stated to alleviate the low idle problem irt the accessories turn speed.

MM03MOK
06-06-2005, 07:04 AM
A couple of others said that the idle can't be adjusted through the computer.
What's the story? How have others who have UD pulleys handled this?
Yes, the idle can be adjusted through the computer, and we did just that at Indy last year....brought our PCM and Dennis raised the idle rpm (100 I believe) while he adjusted for our 4.10 gears.


Also, if I can get a computer reflash, will that mess up the aftermarket chip that I have?The aftermarket chip overrides the computer. You need the chip reburned or the tune on the chip flashed to the PCM directly, with the idle adjustment.

:bunny:

RF Overlord
06-06-2005, 07:07 AM
The speed shop said to just adjust the idle mechanically by turning the screw. I'm still afraid to do it that way. You should be...don't do it.
A couple of others said that the idle can't be adjusted through the computer.They're wrong.

Having underdrive pulleys doesn't actually lower the idle speed of the engine, it just reduces the rotational speed of the accessories. The best way to offset this is to raise the idle speed by having your tune modified. If you have a chip, you'll need to get it back to the tuner to have him re-burn it with the new idle specs. Or you can get one of the new X-cal2 boxes and do it yourself, and sell your chip to someone else...or keep it as a back-up.

Also note that the idle speed actually has two steps...idle in neutral/park and idle in drive...I had the idle in drive raised by 100 RPM (IIRC) and my A/C problem was gone...

*EDIT*: Dang, the Bunny Lady beat me to it... :P