Re: 1997 Lincoln Town Car: engine surges

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Re: 1997 Lincoln Town Car: engine surges

Backyard Mechanic

30 Oct 2006 18:28

>> it to cover up an IAC problem, the IAC will not be able to
>> properly control the idle even if it is replaced. Setting
>> the base idle must be done "by the book".
>
> Isn't it necessary to recalibrate this after replacing the IAC valve
> anyway?

No... has nothing to do with the IAC, except to keep IAC air control
within proper range.
If they adjusted the stop screw to increase idle speed, the IAC might hit
the internal end of travel when starting in very cold weather. With
resulting hard to start symptom.

Once IAC is replaced, get a tach and check for approx 550-600 rpm when
engine is up to temp and IAC connecter off. If higher than that, adj to
550 rpm or the rpm stated in book.
That rpm is for v-8 only.

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zwsdotcom@gmail.com	30 Oct 2006 01:58
> it to cover up an IAC problem, the IAC will not be able to > properly control the idle even if it is replaced. Setting > the base idle must be done "by the book". Isn't it necessary to recalibrate this after replacing the IAC valve anyway?

lugnut

30 Oct 2006 01:36

>> One other pattern: the car only does this when I've got
>> the heater or A/C on.
[quoted text clipped - 6 lines]
>Dont know what else could affect the idle speed, its controlled
>electronically, no any adjustments,

As is the case with the OP, your problem is also likely an
IAC problem. If the IAC is working properly, you will have
to pay very close attention to ever know when the a/c
comprerssor is in or out. Many times, the IAC can be
cleaned by soaking the valve end overnite in a good solvent.
You can also just bolt in a new one from a dealer for about
$80 or aftermarket for about $50. Either way, the IAC is
the likely problem. You should never adjust the idle stop
screw. That controll the engine base idle. If you adjust
it to cover up an IAC problem, the IAC will not be able to
properly control the idle even if it is replaced. Setting
the base idle must be done "by the book".

Lugnut

tomasz.kk@gmail.com

30 Oct 2006 00:21

> One other pattern: the car only does this when I've got
> the heater or A/C on.

maybe its related to A/C compressor which obviously takes some power
from the engine.
mine 4.6 does the same, its normal i guess. Without A/C it idles
fine, i have new ignition wires, new spark plugs and MAF cleaned,
and air filter new too.
Dont know what else could affect the idle speed, its controlled
electronically, no any adjustments,

The Derfer

29 Oct 2006 20:16

I've got a 1997 Lincoln Town Car, Cartier Series.
I notice that when idling in the Drive Gear, the car sometimes
surges ahead, occasionally with force a bit stronger than
the force with which I've got the brakes holding it back.
And sometimes, the engine dips really low, almost to the
point where it seems like it's going to stall, which
thankfully it doesn't.

One other pattern: the car only does this when I've got
the heater or A/C on.

What could this be and how might I repair it? I took it to
Midas and they adjusted the idle, which helped but didn't
ultimately solve the problem.
TIA.

-The Derfer

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