H/C/I Auto Idle help

[Tigre_loco]

Hello everyone. I just finished up a build and the combo is as follows:

2002 Chevy Camaro A4 stock bottom end
PRC 227 heads 62cc's
TSP MS4 cam 239/242
Fast 102 with Nick Williams 102 TB
4l60e w/ shift kit and a Yank ss4000 converter

I believe that sums up the relevant info on the car.

I finished up the build and got tuning. I began with the VE tables then moved on to the MAF tables everything went fine. I finally began to attempt tackling the idle tuning. I ran into some issues.

To accomplish the idle tuning I adjusted the spark tables main advance as well as idle advance. From there I loaded the tune and proceeded to attempt to tune the RAF tables using the RussK Idle-Air config. I input the numbers I got from the config and the car began to idle worse and worse. I could not start the car with out giving a little throttle and it would not hold idle on its own. I ensured the TB blade was opened up enough to achieve decent counts (20-40ish) at hot idle.

I could not make any progress on getting the car to idle using the values from the russK configs. So I began to add to the RAF tables until i was able to get the car to start and idle on its own. From there I got a cruise control effect when driving and the idle hangs when off the gas and rolling at speed. It does not return to my desired idle speed until a complete stop has been made. A quick blip of the throttle will result in a hunting idle and at times the engine will stall while at others it will hold idle again. I adjusted throttle cracker and follower slightly to try and correct the issue but no luck.

I'm not sure if I need to make any changes to the IAC steps vs. effective area table for the enlarged TB and if that may be what is messing up my RAF numbers? But that's just a speficic thing I was unsure about.

I am still learning and have read through many stickies, tutorials, guides etc,. I also have the GM EFI tuning book by Dan Maslic. I would appreciate any help, advice and instruction that you can offer me. I have the tune that is currently in the car, two logs one driving and the other parked idling with a blip of the throttle and the car dying. I also have the config I used while logging the car. I logged a lot of things in hopes to provide any necessary info to get me pointed in the right direction. If any other parameters need to be logged or any specific scenarios need to be logged I can provide those.

So please help me figure out where I am going wrong on this tune as well as how I can correct it! Let me know if you need anything else to help me. Like I said I am also learning so please don't be too harsh on me for any Nooobie mistakes I may have made in the tune. Thank you in advance!

[ns158sl]

Is your scaling correct for the throttle body? If you have to pedal it to start.. you need for startup airflow.. If it cruise controls.. you have to much running airflow.. whether its cracker or base. log log log.. create tables, histograms, and graphs....

Eric

[Tigre_loco]

I'm not sure I will look into that and see what I can come up with. Would it be the IAC steps vs. effective area table that I'd need to make changes to?

[Russ K]

Tigre_loco, try this tune, never had to change the IAC steps vs. effective area when using a larger TB. Do another cold start idle scan in P/N till operating temp, then repeat in gear. Just copy the idle desired airflow (last value) histogram & paste into the RAF table of the editor. For the colder temp cells you didn't get data, just make those cells the same difference from stock as the next warmer cells.

That MS4 has a lot of overlap and will be a challenge to tune, and will never be very driveable at lower RPM/light throttle.

Russ Kemp

[Tigre_loco]

Russ,

I replied to your post on ls1tech before I seen this here. I'll get the car back this week and load this tune and run the scanner. I'll post back with my results as soon as I get them. Thanks for your help!

[Tigre_loco]

Tigre_loco, try this tune, never had to change the IAC steps vs. effective area when using a larger TB. Do another cold start idle scan in P/N till operating temp, then repeat in gear. Just copy the idle desired airflow (last value) histogram & paste into the RAF table of the editor. For the colder temp cells you didn't get data, just make those cells the same difference from stock as the next warmer cells.

That MS4 has a lot of overlap and will be a challenge to tune, and will never be very driveable at lower RPM/light throttle.

Russ Kemp

Hey Russ,

I got a chance to get over to the car and load your tune and run the scanner. The car started and idled great with the tune you provided (final-2). I ran the scanner while in P/N and copied the values from histogram one (last values) into the RAF tables of the tune. Loaded the new tune (Final-3 p.n.raf 1) started the scanner and started the car. The car started right up then died after a few seconds. Started right up again and died again. I reloaded the final-2 tune and the car started right up and satyed running. I gave some throttle blips and it came right back down to idle as it should. Put the car in Reverse and blip the thottle and it wanted to die but caught itself and idled again.

I'm not sure if I am doing something wrong still while running the scanner that I am getting the wrong values? I ensured they were both in g/sec.

[Russ K]

Is your car in closed loop? As if the fueling is out, it will take a while for the fuel trims to learn. Looking at the final-3 scan, you need to lower the RAF as your LTIT & STIT are negative. But you increased the RAF yet the car stalls? That doesn't sound right.

Russ Kemp

[Tigre_loco]

Yes, the car was in closed loop. Should I put it in open loop and reset the fuel trims while running the scanner? For what ever reason the LTIT are steady at -3.00g/sec P/N and -2.86g/sec Gear. And with your tune (final-2) loaded the STIT were less than 1g/sec from 40*C and up till I hit the 104*C table. As you can see in this screen shot of the compare files, I actually removed some from the RAF from your original tune. (Final-2)
screenshot1.jpg

I feel as if the values from the scanner are still leading me in the wrong direction.

[david_viny]

I think you were going in the right direction, its just that the massively negative LTIT remembered from the previous tune caused it to stall.

IMO this is what id go with for RAF>PN

F*______46____68_____90___111___133___154__176___1 98___219
g/sec __17.8__15.80__13.10__9.55__8.20__7.20__6.25__5.55 __5.00

[THE CHAD]

fellas what about the max/min in gear/p/n adaptive idle airflow I do think for that cam/manifold/throttle body I would lower them ie I do think they are abit aggressive for a cam that size....very similar cam to my new custom comp and I did zero out my max tables....102 nw does take a lot of logging to get right and I made changes to my throttle follower airflow/multiplier and also cracker and decay to suit and it did fix my throttle blipping/dipping/stalling issues and drivability....before making changes to those make sure your RAF tables are spot on and try to aim for your STIT/LTIT to be within +/- 0.75- 1.0 g/sec I do like my trims to be on the - side a tiny bit....also it isn't a ETC so don't touch the ETC area scalar leave it at 0.0255 cheers Bret

[Tigre_loco]

Thanks for the input everyone, I will try and get over to the car soon and try some of the suggested changes and see where it gets me. I'll keep you guys posted.

[Russ K]

Leave the adaptive min & max values the way I set them for you. I just gives them a larger range if your RAF table is out a bit.

Russ Kemp

[JamesLinder]

Your idle VEs are too high, which means you are running rich and this will lead to idle hunting big time.
Go with these and see if you get a more stable idle.

Labels 400 800 1,200
15 20.37 29.65 34.04
20 22.09 31.78 37.72
25 23.74 33.91 42.51
30 26.00 36.12 43.54
35 27.37 37.80 44.96
40 28.42 37.36 43.48
45 29.65 37.82 43.86
50 31.91 40.14 44.57
55 33.76 42.00 48.40
60 37.07 43.43 48.33
65 37.81 44.41 48.25
70 38.31 44.92 49.05
75 38.76 45.66 49.84
80 39.42 46.42 50.71
85 39.77 47.17 51.51
90 41.35 48.28 53.58
95 42.40 49.79 54.86
100 43.92 51.36 56.20
105 44.06 51.36 56.20

[JamesLinder]

MOST IMPORTANT thing for good idle if you have a throttle cable set-up is to get the throttle blade position screw adjusted properly.
You want enough air at warm idle in neutral so the IAC counts are in the correct range. ALSO, must have the throttle position sensor
set to ZERO when the car is starting up - anything above 0.4% will simply not work. If TPS is not reading 0% at idle, then must unplug
the electrical harness from TPS and IAC with ignition key turned off, then turn key on and leave on for about 20 seconds. Then plug
harnesses back onto TPS and IAC and this should reset both of these to correct zero calibration. The TPS 0% can be lost after loading
tuning changes and is also most usually lost when adjusting the throttle blade screw. If you do not have a 0% TPS at idle then any
other adjustments would be wasting your time. TPS seem to go bad way to often, and if you do not have reasonable TPS % readings
through the entire scale as you push the pedal down then get a new one because yours is crap.

If you seem to not have enough enough IAC air even though your counts are in the right ballpark (38 to 48 at warm idle in park or neutral)
then you can revise the front end of your IAC table to the following:

IAC Steps 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0 15.0 25.0 35.0 45.0 55.0 68.0 80.0 90.0 99.0 108.0 116.0 122.0 128.0 133.0 136.0 140.0 144.0 147.0 150.0 153.0

These are higher settings at front end of curve that GM used for the pre-2002 vehicles, whereas you are using
the ones now that were OEM for your car and should work if other settings are correct. I would only use the
above values as a last resort.

[JamesLinder]

Also, what is your MAF air reading during idle in gear sitting still? Should be around 2.0 to 2.2 lb/min. Also,
your dynamic air and your MAF air readings should be very nearly identical at idle because one is telling you
what your VE table is estimating and the other is what your MAF is reading. If after loading the new VE values
I gave you, check to see that your MAF reading and dynamic air are at least close to being the same. I believe
your ST Adapt values are way too high, as well as the adaptive idle max and min values. Find another tune on
the forum similar to your vehicle and use those. Or, buy a mail order tune from FROST because he is one of the
best.

Although mine is 408 stroker with slightly less camshaft and different PCM (2000 Camaro) you can get an idea
of what start up air, adapt air, max and mins, etc are reasonable for a modified motor. This is perfect tune on
mine and not everything is translatable to yours because you have a different PCM.

[Tigre_loco]

Thanks for everyone's input. I got the car back and have been working at the RAF tables. I've got the Idle trims nailed down and idling nicely now using Russ's base tune to start from. My IAC counts are ok I believe. I've adjusted the tps to ensure the voltages are where they are supposed to be and it seems as if the car is beginning to get where it needs to be. I have to run the Idle-air config a few more times in gear to get it as good as I've gotten the P/N table but it is pretty close now.

The only issue I seem to be having currently from a stand still idle is in reverse. In Drive I can blip the throttle and it will come back down and idle but if I do the same in Reverse it drops down and comes close to stalling out or will actually stall out sometimes. From what I noticed in the log of Drive vs Reverse, it seems like the throttle follower decays much faster in reverse than it does in Drive. I don't see any where to adjust the follower decay for reverse? Here is a log of what is going on. Any advice is greatly appreciated! Thanks.

If you use my config you will see when the car is in park/D4/reverse. Take a look at the follower when I blip in drive vs. in reverse. It drops much quicker in reverse.

[JamesLinder]

post your tune so I can take a look at it.

[Tigre_loco]

James,

Here it is.

[JamesLinder]

Took a quick glance and appears will need some changes in RAF and idle timing I believe. Will work on this tomorrow or Tuesday and post recommendations. Start
up air looks way high, throttle follower air way to high, target idle RPM at normal operating temps (warmed up) are too low, idle air at normal operating temps
too low. Quite a few changes will be needed. you may want to pay me for 2 credits or whatever it takes to license your file for me to make changes so you can take from me and load directly into your PCM. Might be easier.

[Russ K]

The only issue I seem to be having currently from a stand still idle is in reverse. In Drive I can blip the throttle and it will come back down and idle but if I do the same in Reverse it drops down and comes close to stalling out or will actually stall out sometimes. From what I noticed in the log of Drive vs Reverse, it seems like the throttle follower decays much faster in reverse than it does in Drive. I don't see any where to adjust the follower decay for reverse? Here is a log of what is going on. Any advice is greatly appreciated! Thanks.

Looks very good, I don't see any tables for the throttle follower in reverse. Not sure why you want to blip the throttle in reverse. Your idle speed is not too low for your cam. The RAF looks very good as per your STIT & LTIT. Don't touch the idle spark timing, or the start up airflow (that is used so that you don't have to hold the throttle open when starting the car). And leave the throttle follower alone, as that is to prevent the idle dipping or stalling when quickly lifting the throttle.

On this tune, I just make some changes to the idle underspeed spark timing. But that's not going to help much, as the adaptive idle spark is disabled until the throttle follower and cracker are at 0.

Like I said before, that cam will be a challenge to tune.

Russ Kemp