Nathan Plemons

Hey guys I've got a strange little quirk with my car lately. Actually it's not all that strange, I know exactly where it originated. I tuned my idle a little lower than it had been previously and now it doesn't like the A/C so much at idle. Here's the strange thing though. If I am moving with the car and turn on the A/C it will run perfectly. If I just sit at idle and turn on the A/C or start the car with the A/C on it will want to run rough and try to die. All I have to do is give it a little gas and it will settle down into a nice idle, it just doesn't like that initial engagement.

Is there anything I can adjust that would help this along short of just raising my idle back up?

The car is a '92 and I have all the chip burning capability and software.

Alvin

Try moving the IAC park counts up a bit.. that may help a bit

DVNCI

Hey Nathan, I was having the exact problem after lowering my idle down to the 750 we talked about (if I remember that's where yours was), it was just too low for the A/C and I even had it virtually die a time or 2 when coming to a stop and turning at the same time.

I took it back up to 925 tonight and that helped a lot. It also seemed to smooth out my take offs as they were a little rough.

I put in your timing map tonight and I think I could tell it helped. Then I tried the ve tables as well and that didn't seem to make much of a difference (as you thought) though I would still like to get it on a dyno sometime soon.

When you gonna have a chance to come over and drive my car? :-)

I really want to get your feel for how you think it's running. Something still seems off to me!

Later!

Alvin

DId you try what I mentioned? Too bad the 92-93's don't have a idle adder for ac request.

DVNCI

Oh, and I agree with Alvin.

I assume it's more or less the same with LT1 Edit, but on TunerCat there is an "IAC offset for A/C Anticipate vs A/C Pressure" table that just has steps in it. I'm thinking of bumping mine up a little as well.

-=Jeff=-

They Don't!!!! wow, my 91 L98 Code has it.. that is what I used

Alvin

Nope, strange isn't it. It would be really helpful in cars with big cams that arn't happy idling with AC on.

Nathan Plemons

Alvin,

I looked and my IAC counts are already a good deal higher than stock, I had to play with them a while back to get the car to behave correctly with the Holley TB. The real simple solution is just to raise my idle back up to what it was previously. I was more curious to see if there was some table such as the one mentioned that I was just overlooking. I guess it just really isn't there.

Alvin

Yes there is, the park counts

if it flys to the park counts, then realizes those IAC counts are too low and has to fly back up don't you think there would be a surge

Morley

Change the "Target Idle RPM vs Coolant Temp (in drive)". Stock is 525 at warmer temps...too low, try setting it to 650.
You'll alos want to change the "Target Idle RPM vs Coolant temp (in park/N)" to the same or a tad higher....say 700.

Nathan Plemons

The car is heavily modded, and it's a 6-spd. As far as I have been able to tell it only ever uses one of those tables. The idle is already set well above 525.

Morley

Ok, for a manual you should only be using the "Target Idle RPM vs Coolant temp (in park/N)" table.

STL94LT1

I'm having the same problem as Nathan. But, my car is a 94. How high should I adjust the steps.


-Mike

DVNCI

Your car will definitely have the table I mention above, there is only one IAC table relative to a/c

STL94LT1

I found the table, just don't know how high to adjust the steps.

DVNCI

I've got:

0
0
0
0
0
2
4
6
8
9
10
10
10
10
10
10
10

And that seems to work OK but I think mine needs to go up a little too with this new cam.

STL94LT1

Yep, those are stock. Maybe Alvin will chime in with how high to increase each step.

Alvin

I shouldn't tell you how high to increase each step. Use trial and error to find the best thing for your car. When it comes to tuning trust nothing you read on the internet until you try it yourself. If someone is giving you tables to load into the car your not really tuning it yourself are you?

Try bumping it up 15 counts and see where that takes you.

Nathan Plemons

Kevin, use Datamaster and see what kind of IAC position the car is holding when it is idling. That should be able to give you some idea of how to pre-set the tables in the computer.

STL94LT1

Thanks Alvin. I just needed a starting point.


-Mike