Hi Grady,
My sig combo is another Mustang I have. I have five cars.
This one is the $600 Vert, '94 GT 331, Cobra intake, 24#, 65MM TB, 76Mm C&L, Stage 1 cam, GT40Y heads, 1.7:1 Crane rockers.
I'm not sure, with the T4MO, how to influnce idle A/F ratio, unless you run OL all the time. I know the engine will idle, at 600 RPM, with a rich idle.
My K's are running near 1. I data logged a typical stall, if you want me to e-mail it.
Another thing I have wondered about:
When I come up to a stop, idle will come down to 900RPm, until I get almost stopped. Then, I see the RPM blip up, about 100RPM, and then come down to normal 800 RPM. Why does the idle blip up? Why doesn't it just go down to 800 RPM?
Eric
Eric
So many things can influence the idle on a 94-95 Stang and the frustrating part of it all ... some of them are most likely not causing a problem what so ever.
But ... one or more of them may be the guilty dog causing you to be an unhappy camper here.
You end up just looking at all those various things to see if anything looks outta whack I guess you could say.
I'd start off with mechanical adjustments first.
You want the tb blade stop screw just barely holding the blade off the side of the tb bore ... Really ... that is its main function as opposed to setting the idle anyway
As you know ... the idle is really set by the pcm.
The bleed screw on the tb can cause the famous hanging idle if open too far. I have seen peeps have good results in a range or two to three turns out.
IIRC, I've seen the most stable idle with an isc duty cycle at around 35
You are supposed to have a slight increase in idle speed until you almost come to a dead stop ... but not anything like 500 rpm or more like you see if that bleed screw is too far out.
Dizzy at 10 with spout in place of course.
Now for some pcm discussion
First thoughts are a surging idle is usually a sign of being a bit fat
Since you got those 24# inj's ... I'd move to the j4j1 file faster than a heartbeat
It really works nicely with modded Stangs that have moved away form OEM inj's and meter.
That TFS stage 1 cam ... while I would not call it radical ... it ain't no super wide valued lsa or milk toast cam if you ask me. IIRC ... its like 110 lsa ... or ...
am I not remembering correctly
anyway .......
The more narrow the lsa ... the more you may have to work with various adjustments is what I've seen be the general all around rule of thumb.
I looked to see if you were running LT's as they can sometimes cause a bit of grief
with idle issues.
I gave a fellow some help in a very round about way about a week ago who like you was dealing with idle issues. I've heard nothing back from him so maybe it worked out for him.
He was running the j4j1 file like me so I looked at my values and a couple other files of similar combos and just gave him some percentage of change values.
These are based upon an unmodified j4j1 file btw
TB airflow scalar ... add about 70%
ISC Neutral Idle Airflow points ... add about 10%
Now ... There are procedures you can go through to get closer but you could easily try these to see if you find some help.
You have loaded in the offsets for those 24's ... Correct
If not ... Go over to the Tweecer site for the values and load em up.
You say your K's are running near 1
however
Here is where you can't be talking in a ball park kind of way as you use the values to determine if your fat or lean at idle from an adaptive perspective.
Values < 1.00 means the adaptive is pulling fuel cause you're fat
Values > 1.00 of course are opposite here
You could certainly + or - the maf cells (depending on what your K's are telling you) at idle and like 1 above and 1 below to see if you find some relief.
Man ... I almost forgot ... You have loaded in your new cubic inch size ... Correct?
If not ... your load at idle could be a bit off.
Try some of this stuff Eric
and
If I didn't make sense with some of this ... holler back
Grady