Bink

Dang good point!

WS6FirebirdTA00

iTrader: (33)

thanks for the info man. with no ac its hard for me to test things and he is 5 hours away haha. if we figure this out soon we will post up what we had to do

Bink

Your welcome.
Mine ( Electronic Throttle Control - 90 mm Nick Williams) stumbled hard and STIT jumped 3.5+ g/sec when I turned on the A/C. Then when I turned the A/C off it would learn downwards the 3.5 - 4. g/sec....LTIT and STIT would go negative BIG time. Then the damn thing wouldn't restart if I shut it down ........took me weeks to figure out the mechanism and really screwed with my LTIT and STIT tuning!

Jimmyz

iTrader: (3)

Bink -

The "AC Offset Min - In Gear" - was set to -0.50. Youre saying I should try to add 1.0-1.5 g/se to that number/field?

Jim

Bink

I would try it at -1.0 or -1.5 g/sec. That way it will offset a reduction in airflow.

Patrick G

iTrader: (14)

Jimmy, I can tell you with confidence that your IAC effective area table is too steep past 100IAC counts. Make sure you get your idle with the AC off to be around 30-50 counts when fully warmed up and the IAC counts with the AC on to around 80-100. If yours are higher than this, then you already have a problem. The fix is either drilling the TB blade or cracking it open more with the set screw.

Once you have that done, you'll want to get your DES IAC airflow and Dynamic Airflow to match at idle with the AC off and the AC on. Once you get past the AC idle, you'll want to flatten the rate of increase in the IAC cells quite a bit. You really shouldn't be hitting 310 as early as you do. Mine max out at 260.

WS6FirebirdTA00

iTrader: (33)

from a cold start with that table he has (which is similar to mine) the dynamic and desired airflow match each other very closely. if they match i dont really see how the steepness of the curve matters, as long as it is set up properly. that is where i am getting lost, can you explain that? he ONLY has the problem when the car is moving which makes me think faulty STIT numbers are being kept in memory once he gets on the gas, or the odd throttle cracker airflow tables in the 2000.

Patrick G

iTrader: (14)

Problem is, once he is moving, the IAC will follow to try to match revs with the motor. Let's say at 0 mph, the motor requires 100 IAC counts to idle with A/C on. But once you start moving, the IAC counts will continue to rise with speed. As you're travelling 30 mph, look at the IAC counts. They'll increase as you gather speed. By the time you've hit 30 mph, they're probably in the 200 range with the steepness of the curve. If they are, then the motor will idle like it has a 200 IAC count when you let out the clutch (like if you were slowing down for a stop sign).

By flattening out the curve after the idle portion of the tune, you will not show as many IAC counts at speed. At 30 mph, the counts should only be in the 130-150 range. This way, when you let out the clutch, the rpm will not rise, nor will they stay high and hang there. Does that make sense?

WS6FirebirdTA00

iTrader: (33)

yeah but if you change the iac steps in the effective area it will no longer be accurate. it opens up with desired throttle cracker airflow when moving. so if anything that table needs to be reduced to get the counts lower. right now the curve is right, once its right the airflow tables need to be adjusted to make everything else ok. which is what i have him trying to see if it works. i get what you mean, but from my understanding the effective area table is there to match the dynamic and desired airflow so the car knows how much to open the iac motor for a particular airflow....does that make sense at all? sometimes im confusing haha

WS6FirebirdTA00

iTrader: (33)

ok well looking at the logs when he is driving and the rpms hang the dynamic airflow is WAY off from the desired idle. now the question though, why on a cold start will the dynamic airflow be fine at an IAC count of 200 and driving the IAC count with the ac on at 200 is off by that much.

my understanding of effective area tells the computer that at a given iac step the open area for air to travel through is in that table. well how come at cold idle they are right? only thing i can think of is going down the road it gets more air forced in there or something. kinda screwy if you ask me. ill redo the effective area table for him and have him try cause after looking at the log it has to be off by 50-60 steps now. i just want to know why, anyone care to explain how it can be ok at cold idle and not when on a hot cruise? ive got the logs and can post up screen shots if need be to explain it more

Steel Chicken

iTrader: (3)

he never sent me logs, id love to see them

Patrick G

iTrader: (14)

I sent Jimmy a revised bin file with some recommendations. He can elaborate on them after he's plugged them in. Basically he needs more timing at idle and low rpm cruising and lots less IAC once he gets past idle speed. No need for dynamic air and desired idle air to match at 30 mph. That may be part of the problem. You want the rpm to fall when you push in the clutch at speed. If the dynamic air and des. idle air are always matching, then the idle speed will always match the rpm that your cruising.

WS6FirebirdTA00

iTrader: (33)

my effective area is set up just like his and when i push the clutch in going down the road the iac counts are anywhere from 100-120 and the airflow overlaps perfect and the idle goes down to about 1000 rpm when moving (which is what i have the throttle cracker set up for that airflow for that rpm). i agree the timing needs to be bumped. after talking with rick it makes sense, the only thing is those timing tables were recommended from guys with similar set ups. i have not messed with high compression and more cubes so i didnt wanna take any chances. i think that will smooth his idle out but i dont know if the timing will fix the hanging idle. when he is at idle with the ac on there is no issue its just when he is driving and puts the clutch in. i just went out and logged my idle stuff at cruise with many different iac counts and when it was hot i could get them to go anywhere from 30-150 and the airflow stayed the same and it recovers with no issue, i wonder if the ac being on just throws that stuff out the window or what? like i said this is the first time i have tried any ac stuff before so i dont know what the proper changes are. i would imagine the torque needs to be scaled based on the ratio of the old vs new pulley diameters. smaller pulley means less torque transfered through the ac tension/belt. jim if you can measure the diameter of the pulley on the car now i can come up with a scaling factor to fix that table. and ill have to see if i can find my stock pulley and measure that. if it thinks it needs more toruqe when it really doesnt that will keep the rpms up, but i dont know about as high as they were but it woudlnt hurt to get this table right

Patrick G

iTrader: (14)

I can't say it too many times, the IAC Effective Area table is too steep past idle speed. Jim should not be logging IAC counts in the 200s while cruising with the AC on. The curve you made for him is great up to 100 counts. After that, it should get more shallow. The added timing works great with big cams as it will get the IAC counts down at low rpm and eliminate much of the need to have such a steep slope on the table.

I tried out the more aggressive timing tables on my car and they work fine with 11 to 1 compression. Jim's car should like them as well.

Jimmyz

iTrader: (3)

Only problem is my compression is 11.8:1...think it will still not knock?

Jim

WS6FirebirdTA00

iTrader: (33)

yeah i understand but what i am trying to say is that i have a curve i did the same way and it works perfectly in my car, i can go down the raod, set the iac to 200 yeah the idle goes up but my airflow lines overlap, his dont. if you lower the values there then it will not let enough airflow in on a cold start, then to fix that oyu have to compensate iwth the idle airflow. i just want to knw the reasoning behind what you are saying. Jim can crack open the TB and get the counts to be low without a problem. but by doing this you change the effecitve area so either way it lets the same amont of air in, the iac values doesnt mean **** really, it all depends how far open your blade is (which his isnt open far) there has to be some other reason for this. im gonna have him do a cold log with the ac on to see what it has for airflow at those iac counts on start up. our curves are the same profile.

how do you set the table up if you say its too steep? i just wanna know if i am missing something here. in the end, effective area is effective area and shouldnt change unless there is some outside factor effecting this such as airflow from speed. then i can see what you are saying because with the larger steps the increased airflow into the air box will increase the dynamic airflow, making the idle hang. only thing that gets me is i dont see this on my car with higher iac counts.

WS6FirebirdTA00

iTrader: (33)

Rick runs high timing table like that in 12.1:1 cars so i think you will be ok

Patrick G

iTrader: (14)

The problem is you don't need to have your dyamic air and desired idle air matching while you're cruising. It only works when you are at 0 vehicle speed. The increase RAF will add the correct amount of IAC. You've got your tables set well for running with no AC and a modified TB. Jim obviously doesn't need the high IAC counts when cruising. I repeat, once you get past the idle area of the tables (usually up to around 150) don't need the IAC's help as much once you're running. Any values in the 200s while cruising is going to cause problems when you push the clutch in.

WS6FirebirdTA00

iTrader: (33)

so if he opens his tb, and we redo the VE table, and drop the idle counts down about 40 or so to about 30 you think that would help the problem out then? i shot him an email over telling him about that, definately wont hurt to try to adjust the tb anyway to get lower counts. im also gonna fix the ac torque settings since with a pulley swap they shoudl be changed anyway.