Stop bad fuel economy, eliminate idle and off-idle surging, regain that stock feel

[bullygoat]

This has got everything you wanted. Also got the closed loop status bit in there.

Tim

[MNR-0]

bullygoat,

Try disabling your ltfts by setting their enable limit to 140*C. Other than that, I cant see anything that stands out to me. I dont thionk that will solve it. You should also try reflashing your stock tune, and just playing with getting into open loop.

[OldSkool69]

MNR-0

Sorry for the dealy, to much work yesterday. Anyway, I have a log of the idle and off idlle and even when it dies on a fast stop.

It a 5.3L with cam (232,230, 580, 580 110LS) and StgII heads

Thanks

[Russ K]

Bullygoat, I looked at your scan log. I'm out of ideas at this point. The car should be in open loop at idle with your set up. On my 2001 ZO6 with a 234/228
cam, the car idles in closed loop. I tried open loop using your set up and there was no improvement in idle quality (yes, my car would idle in open loop)
Try this file, I set up alot of the O2 tables, over & underspeed timing tables,
Pe and added idle speed & running airflow. Also added base timing, check your main spark tables as you have less than stock timing in some low load areas.

Russ Kemp

[OldSkool69]

Heres the idle log guys, did not attach before

[MNR-0]

OldSkool69,

The log file config you used is not the one I attached in this thread. Nevertheless, from what I can see, you are running open loop at idle. However, it doesnt seem to be stable to me.

Remember this, Idle tuning in open loop is not a panacea for all symptoms. It must be followed up by other standard and accepted methods for idle tuning, like running ariflow, timing advance and VE/MAF for airflow. Also note that if you already have a good idle tune in closed loop, there may be no gains going open loop - apart from the fun of it. I did it in an effort to reduce fuel usage - first and foremost. Luckily for me there were other beneficial side effects.

Your log, OldSkool69, shows a lot of surging and goign by your O2 sensors, you are not rellay much leaner than closed loop. You have similar vacuum to me so you kmust be running a reasonable cam. The first thing I would do is try to lean it off more.

You really need to log the equivalence ratio to determine why you are going rich at 2000RPM. Also note that if you HAVE NOT zeroed out your LTFTs (which it seems you have not) like PE at WOT, you will get erratic fuel dumps as the VCM compensates for what it thinks is a continual lean condition. This could help alleviate your surging and off-idle problems.

If you wish to presist with this method, I would restart it, following it word for word, making sure you reset your fuel trims in the process. Log the results using the config file I attached. You have too many PIDs in your log - its not terribly high resolution and you dont need to log all those PIDs anyway.

1. Make sure your main spark map has identical timing values for all cells 0-0.28g/cyl and 400-1200RPM. Ramp up the timing from there at no more than 4* increments. You need 20* idle advance minimum.

2. Make sure your VE map around idle, which shoudl be 60-75kPa and 800-1200RPM conatins VE values within 2-3% of each other to eliminate large fuel swings.

3. Your idle advance fluctuates from 16* to 35*. This is singularly the largest contributor for your on-off idle problems. My recommendation would be to run a singular 28* idle advance and remove the 40* advance logged at 0.08g/cyl.

4. Add some airflow for your fans. 0.37/0.75 Fans 1 and 1+2

5. Zero out your cracker 400-1000 and 0-32mph

6. Keep your Follower settings stock. Just bump up the decay values 0-3mph by 100%.

7. Zero out all your adaptive idle delays. This will ensure adaptive idle control as soon as idle conditions are met.

8. Zero out your adaptive idle RPM err. time. No sense in waiting for an idle update to occur if you know its already off-scale.

9. Blend in your VE map at 1600RPM. Its too much of a cliff from 1200 to 1600RPM. Just use the smoothing functions to blend in from 1200RPM to 2000RPM. You will get surging from 1200-1600RPM with that VE MAP of yours.

10. Copy over your main spark table to both your idle spark tables, drive and park. Make sure you have smoothed and flattened out your spark to 28* as per recommendation #1 beforehand.

11. Halve your idle overspeed and underspeed corrections up to 50RPM, then blens in to 300RPM. You want to eliminate over-corrections and move timing around as little as possible.

12. Check your running ariflow and adjust to suit.



What we are trying to do here is two-fold:

1. Maintain a steady idle advance with as little idle advance corrections as possible and...

2. Maintain a steady AFR with as little VE variations as possible



I do not have a licence for your vehicle type so I could not just make the changes to your bin file. As you can probably guess by now, I dont think the issue is runnign open loop with your idle and off-idle tune, rather the idle tune itself.


Regards

[OldSkool69]

MNR-0

Thanks a lot for ur instructions. I was feeling so do tire triying to get the off idle right. I was giving up. A Truck that I love, was turning the way around, and not wanting to dirve it to the corner. Right know I'll change and follow ur instructions and test it and log the results.

As you might notice, I'm kind of far from any dyno or tuner, kind of the first in this around here (Guayaquil, Ecuador) ANd your forum is all I got.

I really am grateful for your help.

P.S.

I have no electric fans, palning to install some flexilites as soon as I make the truck driveble. I follow ur tip on the stall converter, but didn't find the brand you state, so I bought TCI 3600.

[OldSkool69]

MNR-0

As an Ozzy, you might understand that I also have installed a LPG multipoint injection system for the daily drien issues and on the strip I use 110 Octane fuel only.
The system system is from technocarb. But all the main components are maid in Australia

now for the tuning whish me luck

Gabe

[OldSkool69]

MNR-0

Dude, those instructions totally rulezz.

The on off idle came down peacefully. My idle issues where never on a stop, where on and off.

I have one question, and sorry, but I'm new on HPtuners software, How do I adjust the running ariflow? In which tab?
On what paremeters do I base my changes?

Other than that the idle smooth a lot and the only problem I have now, is specifically, when I floor the gas and took it off rapidly, and press the brake pedal, it dies.

But on a normal driven, the idles return normaly to the desire RPM.

Theres no issues off idle hard or soft.

Every time in heavy trafic, if I hit the gas pedal to hard and let it go as fast, and brake, the car dies too. Smae as before but not to hard on the gas, just to 2000+rpm, remember my converter.

Thanks a lot MNR-0, at least tonight I'll be driving it with more pleasure than before (just making sure it will not die) and looking out a few sick stangs to hit on

Gabe

[MNR-0]

Base Runnign airflow is critical to maintaining a good idle, as well as returning to idle under severe conditions like what you mention. Base running airflow is like a LTFT for fuel, except its for air.

Find it under "Idle|Airflow". As a general rule, your STIT (short term idle trim) and LTIT (long term idle trim) should not be trying to compensate by adding or subtracting much more than 1g/sec when warm.

There are heaps of therads here describing how to tune your idle with Base Running Airflow. I can't add much to what has laready been posted before so I recommend you do a search for "Base Runnign Airflow" and "Idle Tuning".

I would start by adding 5 to your BRA table and work from there.

[OldSkool69]

MNR-0

I'll do that search now, and read and will try to undertand everything.

On the down side, last night I run across a Porsche Caiman S. Sadly I was with NOS bottle empty. Anyway the guy was roaring the car next to mine. Could not take the rush, on a roll from 40 km aprox. we hit the gas, but on 3 gear changes the Caiman was 4 cars length front of me.
My peace of mind was that I was on my street trim (LPG tank 500Lbs) and no NOS, no slicks, just the 315/35/20 dimaris michellin that on the roll pas on smoke

Next time gadget, next time

[OldSkool69]

MNR-0

Problem solve. no hunting no nothing, just pure satifaction, and just add 2 to the Idle air flow.

Thanks again mate, promisse u rule. Special thanks to 1slowsilverado, your help was awsome too.

[JIM]

MNR-O

Hey, thanks for the imput, I have a 2002 TA, have been tuning the VE table and was nearing 0, (exhaust still smells rich and still have idle surging and dipping) have a 224 cam, LT's and duals, I think followed instructions, disabled closed loop and found the sweet spot (scaled the VE by the ammount) idle better, not cured, smell not as bad but still there, re-enabled closed loop, drove and let learn and LTFT's positive by almost ~ 20, anyone else having this happen....what to do?
thanks in advance for any help

[98A4LS1]

What does turning off the "Spark Idle Control" actually do in the VCM Controls? The reason I ask, as soon as I turn it off, the idle stabilizes (dead stable). As soon as I turn it back on, the up and down idle hunting starts again. This is on a cold startup.
Still running MAF sensor. 224/228 cam w/ LT headers. 50-55 kPa MAP at idle.

No success here on increasing the AFR to try to get engine to stumble. I went all the way to 17.5 and could not detect any change in idle quality.

Lastly, what is the best way to get instantaneous fuel usage w/o a guage readout, by calculation? Log inj flow rate....
Inj flow rate (g/sec) * 8 inj * 3600 sec/hr * 1 lb/454 g * density of fuel (lb/gal)

I'm running the following in "Idle Spark Advance" in "Park"
0 rpm = 20
400 rpm = 21
800 rpm = 22
1200 rpm = 23

I have a slow switching B1 O2 sensor. I guess I need to replace the Bosch 13111 after only 2 months use and try this procedure again. Gas mileage is horrible.

BTW, nice writeup!

Edited: In the instructions to this procedure, which tables are you specifically referring to in the following comments:

7. Zero out all your adaptive idle delays. This will ensure adaptive idle control as soon as idle conditions are met.

8. Zero out your adaptive idle RPM err. time. No sense in waiting for an idle update to occur if you know its already off-scale.

[LS1_Sounds]

Spark Idle Control should refer to the Idle Overspeed and Underspeed spark correction tables. Basically, your computer uses spark advace/retard and IAC movement to control idle. The spark reacts much faster than the IAC, and with larger cams tends to OVER-react. This causes the idle to drop too low, or jump too high, which then causes the PCM to try to correct it back the other direction again. This causes the idle oscillations.

[redhardsupra]

4. Add some airflow for your fans. 0.37/0.75 Fans 1 and 1+2

is there a way to measure how much airflow the fans add?

[98A4LS1]

^^^ Good question!

[LS1_Sounds]

Measure desired airflow, then use the VCM controls to turn the fans on/off.

[MNR-0]

What does turning off the "Spark Idle Control" actually do in the VCM Controls? The reason I ask, as soon as I turn it off, the idle stabilizes (dead stable). As soon as I turn it back on, the up and down idle hunting starts again. This is on a cold startup.
Still running MAF sensor. 224/228 cam w/ LT headers. 50-55 kPa MAP at idle.

No success here on increasing the AFR to try to get engine to stumble. I went all the way to 17.5 and could not detect any change in idle quality.

Lastly, what is the best way to get instantaneous fuel usage w/o a guage readout, by calculation? Log inj flow rate....
Inj flow rate (g/sec) * 8 inj * 3600 sec/hr * 1 lb/454 g * density of fuel (lb/gal)

I'm running the following in "Idle Spark Advance" in "Park"
0 rpm = 20
400 rpm = 21
800 rpm = 22
1200 rpm = 23

I have a slow switching B1 O2 sensor. I guess I need to replace the Bosch 13111 after only 2 months use and try this procedure again. Gas mileage is horrible.

BTW, nice writeup!

Edited: In the instructions to this procedure, which tables are you specifically referring to in the following comments:

7. Zero out all your adaptive idle delays. This will ensure adaptive idle control as soon as idle conditions are met.

8. Zero out your adaptive idle RPM err. time. No sense in waiting for an idle update to occur if you know its already off-scale.

Adaptive idle delays are the Adaptive Idle PID Delay values under the main Idle tab. Default, they are 1.3s. This stopped my car from momentarily dieing before catching idle immediately after a start.

Adaptive Idle RPM err. time is similar to the above, but controls the delay before each consecutive idle advance RPM adjustment is made. The intention here is to make spark idle corrections as needed without delay. I recommend countering over-advance corrections by reducing the values in the Idle Overspeed/Underspeed tables. Keeping the Idle RPM watermark at 60RPM stops advance corrections from occurring too frequently anyway.

20* idle advance is OK. I run 22* at idle. I also have a habit of copying my main spark table over my base Idle advance tables to there is no idle advance difference when coming to an idle state. This can also lead to surging.

Ultimately, you want to reduce as much as possible any idle or low speed surging. Some cams won't respond no matter what you do and as a last resort upping the idle RPM at the cost of fuel economy is the only solution.

[98A4LS1]

MNR-O, I really appreciate you sharing this method to improve idle, gas mileage, etc. and your subsequent replies to our questions. Some of the suggestions in this method/procedure I incorporated in my last tune and it has eliminated some of my idle problems.
My '98 has ONLY one Adaptive Idle PID versus a 2001 Z28 I just looked at which has 5 or 6 Adaptive Idle PIDs.
I have one Adaptive Idle - Startup PID Delay which is set at 1.5 sec. Should I decrease this to 0.5 sec or perhaps permanently zero it out?