A/C, Power Steering and idle

zenboy99 said:

I've talked to a few tuners and Ford people about this. I've been told that on a few vehicles, when the A/C is engaged or the power steering is activated the IAC will open to keep the idle constant for the slight increase in engine load. I haven't found any way to change this on my Tweecer, and how would the computer know the power steering is lowering the idle?

I ask because my car idles real nice and mean at 700rpm, but as soon as I turn the wheel or the A/C kicks in, it will flutter or die.

Click to expand...

Several things come to mind here Chad

If Ed cut your cam with a very narrow lsa like most of those I've seen
700 rpm just might be too low for a stable idle

Here are some areas in the tune for you to think about

1) tb airflow scalar
2) isc neutral idle airflow
3) inj offsets

1 & 2 are pretty self explanatory and we have discussed them a good bit
but
In a nutshell ... they really help the isc do it's intended job

With #3 you load down the batt voltage a good bit when you got the ac on
and crank on the ps thus the inj's are gonna deliver less fuel due to less
voltage available to drive them

IIRC ... You want around 35% isc duty cycle for fairly stable idle conditions

I'd bump up the idle speed to about 900 rpm and see how things go with no
changes other than a pcm reset.

If its good and you want a bit lower idle speed ..........
knock off 50 more rpm ... reset the pcm and see how that goes

Just down the value by 50 until you see things degrade

I can get my 95 to idle at 750 rpm for a fairly stable idle but ......
I just don't like how it draws so much attention at stop lights,
drive through windows, and the like

Grady

zenboy99 said:

Hey Grady, thanks for the reply.

My car has perfect driveability at 900rpm idle set, I was just seeing what I could do at 700rpm

I have a real cheapo battery in the car right now, wonder if I should redo inj offsets?

Click to expand...

Chad

As long as the batt and alt can play nice with each other ... I would not think
a bunch of reprogramming would be necessary if things have been stable
up to this point.

The offsets can really make a difference when you consider the difference of batt
voltage between running around with no accessories and a heavy accessory
load like ac and headlights.

Another thing I found out the hard way is

It can take as much as 30 minutes from a cold start before your batt voltage
will stabilize to a normal range of operation

I did not talk about obvious things above such as maf transfer points at and
around idle or inj low slope cause I know you are not a noob at this
self tuning stuff

Grady