When running Russ K's idle config do you zero out the startup and frictional airflow tables along with the adaptive idle tables? Can some give me a complete run-down on what needs to be done to run this config correctly. Thank you.

 

 

If you do the logs as described above, when you get to fully warmed up temp, check your dynamic air vs commanded idle air. If they don't match (within reason of course), it means your IAC (assuming cable throttle) effective area table is out of whack. When your IAC table is out, you can log desired idle air until the cows come home and not get any better. I had one I did, set it up, thought it was great (early learning days), and then re-ran the log, and everything was 2-g/s lower. SO I copied that into the tune, and the next morning reran it again to make sure nothing changes, and it would barely run AND the thing was trying to cut 2 more g/sec. So to get the car running right, I quick edited the histogram for dynamic airflow instead of desired airflow, pasted the dynamic air numbers into the tune, which worked. Then I worked on the IAC area table until dynamic air and commanded air matched within reason.

The IAC area table is NOT easy to do. There is nothing you can directly log and paste into the IAC table. I ended up logging IAC position vs dynamic air and IAC position vs commanded air, and then used the dynamic air to "calibrate" the commanded air. I had to use excel and do it manually. There is no way you can log the effective idle area, which is one of the axis in the IAC table. But after doing that, I was able to log commanded air and paste into the tune and reach stability.

PS -- I thought I saw you had posted a tune, but I was on my phone. Now I can't find that post now that I'm at a computer

 

Idle Airflow Config is pretty much exactly like Darth said.

Getting the IAC area table right is a bit of a bitch. If you have a stock TB, it should be close. If you have a 90 or 102... well then yeehaw. Time to tune that first.

And that tuning can send you in circles.

 

 

 

Thank you for the quick replies and yes please post the pics of how you have it setup. I had my current tune posted in another thread but didn't get any replies so I deleted the post. If you need it i will re-post it. Do I need to zero out the air adders like follower and startup? My problem is at startup only. The first few seconds it idles low (500-600rpms) at first startup even thou the coolant temp is at 70+ degrees.. I ran Russ K config several times with the adaptive idle zeroed out and O2's off. I'm just wondering if I'm missing something. I can use all the help I can get.

 

I think ima try the way you enter yours manually.

 

Well, if you drill the passage in the TB, you need to adjust the IAC counts. But you have to open your TB and drill holes to keep it below .70V or else it will never read 0% TPS. And then it never goes into idle routines. Which, if your idle is set right, it doesn't need. My car idles without adaptive spark. But on decel or coasting, if your TPS is reading above that, your follower will always try to add airflow unless you zero it out. And that's not advisable either.

I know Darth and I both have idle air counts and dynamic air counts that are within 1g of each other pretty much all the time. I have a NW 102 and I drilled out the hole. The amount of bypass air means that almost half of my IAC table is zero'd out. So I get 30-50 counts hot still. But the commanded air matches the dynamic air - and that's the key to a solid idle airflow.

Point is - running idle air config only gives you what the PCM thinks it needs. It may not be actual. First time I ran it on my setup, I think it was 4g/sec off. Low. So the car stalled out when I went for a drive. I ended up just adding 2-3g to make it work, but the STIT were always at -3g/sec until I corrected the IAC table.

 

 

Try this for Idle Startup Airflow... add a few g there. If it spikes up on startup, especially when warm, bring this down.

g/s -40 -4 31 67 104 140 176 212 248 284 °F
Airflow 4 4 4 3.22 2.80 2.32 1.5 1.5 1.5 1.5


Also try 20 or 50 camshaft revs for Friction Airflow Decay across the board. That will keep decay from happening.

 

Hey, I'm no pro either. I just get a kick out of the puzzle side of this. You're right to drill out the IAC passage to match stock. Many aftermarket TB have a super narrow IAC passage and it can't control very well. I THINK you said something I also seee, which is that the idle correction needs to be minimal or return to idle goes wonky.
I also see that. ON a stock-ish car, 60 is fine. On larger cams, I aim for 30. I think my process is a bit diff than yours, but it sounds like we get to the same place. I will run the car to get to warm idle. Then, play with blade position to get it to hold warm idle with approx. 30 IAC counts. If I get to 0.67V, I start drilling. Then, after all that is done, I look at the commanded idle. Typically, I find that the commanded idle air is far lower than the dynamic idle air. Many solve this by just moving the factory curve to the right by ten cells. That's a decent starting point. I've also found a good rule of thumb is 16 counts is approx. 1 g/sec. So, if it's off by 2-g/sec, I can sometimes just subtract 32 counts from the whole table, and it is close enough. Other times I have to do it the hard way. but it's always my last step AFTER I get the IAC counts down.
Please do repost. It might be something absurdly simple that a fresh set of eyes sees. I wish I could have replied to your other thread. Just wasn't in a position to be able to.
Well said, Jake. This is very often exactly what I see on cammed cars -- especially big throttle body cammed cars. They just need a ton more idle air, because the manifold vacuum is higher. And since the IAC will only flow so much, you have to open it somehow - either by drilling or blade position. both of these mean your IAC error gets bigger, so you end up with more zeroes in the table. In fact, I tend to think the reason the smaller throttles work better for most has nothing to do with finer air control, but rather the calibration more closely matches stock, so it's a closer starting point.

 

 

That's a good way to find how far open the blade needs to be. Shut the IAC all the way and crack open the blade until it runs without dying. If it doesn't, then you drill. That way, your IAC won't kill your car and stall you out. But it allows for more load for A/C or secondary fans, etc. Also, it allows for enough bypass air on cold starts. You're IAC will probably be open 15-20 most of the time like that (once you account for the proper amount of bypass air in the IAC Effective Area table). And now that it's in the 90s here, I'm actually seeing IAC counts around 17-20 when driving with the A/C off.

 

Jakefusion, I've had that table as high as 8g from -40 to 68* which is my problem area with no change in initial startup idle.

 

There's a lot of good info here. I will repost my tune tomorrow (at work now). Honestly, I never paid attention to my IAC's after setting them at hot idle and they are usually around 55-60. My TSP voltage sits at .04 with an occasional dip to 0 but the idle remains very stable for the type of cam I have (Brute Speed Blower Cam). To add to my previous post, I have added over 4gs of air to the Frictional air flow initial table as well with no change in initial startup. I also tried adding fuel thought the OLFA table but it seemed like it was flooding out. Before that I took fuel out of the 'VE table in the startup region (85kpa and up from 400 to 800 rpms) and that helped a lot but didn't fix the issue. BTW I'm using a Edlebrock 90mm TB.

 

If it applies,, I have a Jeep Wrangler,, its a 94, which uses a lot of GM sensors, interesting detail, the 2.5 and 4.0 liter engines, use the same mounting flange for the IAC valve but the housing is different in bore size for both engines, You can use the same solenoid unit on both, but the housing is cast with a ID of either 2.5 or 4.0. The only difference is there is a area about 1/8 in thick that has the hole the pintle for the valve goes in to. the 2.5 housing has a hole about 1/8 of an inch smaller than the 4.0. If you swap the housings between a 2.5 and 4.0 the 4.0 won't idle, and the 2.5 idles at 1500 rpm's.

Wonder if you could machine the TB to accept the jeep IAC housing, and bore it out till the idle got stable. My 2.5 is running the larger 4.0 TB with the 2.5 housing bolted on it.. Thats kinda how I fell down this rabbit hole.. The bigger TB is due to the cam I'm running in the 4banger.. It just needed more air.. The housing is fairly small and its a pretty simple layout.. I think it would be fairly easy to adapt..

 

 

Hello, I added my tune file to the first post.

 

I have played with those tables for a LOOOOOONG time with no noticeable effect to my startup idle condition. They do affect the idle in the hotter regions thou. I have a lot of air in my Base Idle table from -40 to 68*. I got those number by running the Russ K config when the ECT was around 60ish then I just kind-of gussed at the colder temps. My issues occur at startup when the ECT is between 65 and 75*. I don't know if it would have during colder weather cause its put into hibernation during winter time.