Need serious idle tuning (227/241 - 109Lsa)

[02Ls1]

What else can i do to make this cam to idle better?

I've try everything i can and got to the point that i think i went to far on the RAF table.

When i accelarate and let go the gas pedal fast the rpm's drops to 600 800 and then goes back to idle.

I know i need to tune my VE but i want to fix this idle problem.

its a 6.0 with bolt ons on a 227/241 563/546 109lsa

First cam to tune with a big split on duration and a low lsa, any help would be appreciated.

[printmanjackson]

use timing to catch the idle

[02Ls1]

Which timing table should i use? Main spark, idle advance spark?

[WS6FirebirdTA00]

Somewhat, most of your improvement is in the over and underspeed correction tables. Also check out throttle cracker and follower as some OSs need them and others like them zero before the idle cells.

Idle airflow looks way, way too high. You need to fix the spark tables, starts high then goes low then back up just off idle. I would also not run that much timing as you don't leave much room to catch it.

[02Ls1]

Ok i will fix the timing table. I got like like that because whenever i let go the gas timing was going negative eight or so and that was making idle worse.

[WS6FirebirdTA00]

That is your adaptive spark control doing that. Are you sure you aren't looking at the idle advance?

[02Ls1]

No i half the adaptive spark control overspeed and underspeed.

What else can i try to fix it up?

[WS6FirebirdTA00]

Half is going to make it worse. Spark is the #1 thing for idle control and not enough will cause over and undershoot.

[JamesLinder]

Look at ALL of the spark/timing tables and ALL of the air flow and ALL the PID tables in my tune for ideas for your tune. Let me know if you have any questions.

[WS6FirebirdTA00]

Be careful with PID changes. That should really be a last resort doing some of those changes (like making the under idle airflow 2x the over idle). It may work now but it could cause more issues as seasons change again. You basically trick the idle air trims to be more positive, good or bad it has it's own set of issues. Sometimes though you have to do some oddball things, but it is quite rare from everything I have done. My worst headache is my own car and that came after a light clutch swap which made the car not want to hold a good idle at lower RPMs.

I also think 20 deg in the adaptive spark tables is extremely high. I would not want my car to try and have 50 deg of idle timing.

Another key item is trying to bring an idle down smoother. -20 deg on the overspeed tables may at times cause it to come down too fast.

Be aware that each OS responds differently to these kinds of changes too. What works on one may be the worst thing to do in another. Example, my 2000 OS wants throttle cracker zeroed, a 2002 OS I tried needed it or it would try and stall.

[david_viny]

First thing I would do is numb/slow down the IAC valve moments.

Then I would lean out idle some, I'm guessing its rich but cant really tell. Cant go by WBO2 or NBO2 as there useless with a big cam at idle. My car idles with about 3.5-3.8ms injector pulse width, but I have slightly bigger injectors (30vs25lb/hr). I needed to take a ton out of the VE table for my cam in the low rpm area and my cam is a little smaller then yours.

I would lower the idle timing, totally my opinion though, I run stock 22*. Higher timing is tempting as the idle does sound better, but it also ends up being more unstable with any tiny changes to anything else.

engine specs on first tab show a 5.3L, you say you have a 6L, might want to update that. IDK if this will even effect anything but wouldn't hurt.

*Engine>General>Engine size> Actual motor specs, shows 5.3L

This is what I did to slow down my IAC valve from over correcting

*Engine>Idle>RPM>Proportional>Enable RPM Error> 75
*Engine>Idle>RPM>Integral>Enable RPM Error> 22
*Engine>Idle>RPM>Adaptive Idle RPM>Update RPM Error Max> 90

Hope this helps.

[JamesLinder]

No doubt there are various combinations of parameter settings that work well together and if you change any one of them then this could require changing quite a few of the others.

I was shocked at how much the idle settings had to be modified for my build just because I eliminated the PCV valve. The first stroker build used oil (low tension rings from Wiseco are terrible) and this required a lot more timing for optimal performance compared to the set up I have now where the motor does not have any blowby with the Total Seal rings and the crankcase vacuum pump. Evidently oil getting into the cylinders slows down the rate of combustion enough to require noticably more timing.

I highly recommend reading Don Maslic's book cover to cover for tuning tips. IMHO the most difficult task is getting a big cammed motor to cold start without any surging like an OEM tune on a stock motor. Dialing in WOT, VE and MAF curves are not that difficult with the right tools and a little time, however cold start tuning seems to involve trial and error and a little luck.

[JamesLinder]

Idle tuning is difficult because running base air flow, parked IAC start-up air flow, start-up friction air flow, start-up airflow, idle timing, cranking FA ratios, priming fuel, PID settings, IAC position and curve, and other parameters must represent a "compatible" combination and one that gives the motor what it needs. A single parameter being set too high or too low for your specific motor can completely screw up the result. Making things worse is that every modified motor is unique and the same identical settings will not work for any two even if they have identical builds. As WS6 pointed out, each version of PCM operating system also seems to react differently to the settings you choose for some tables. The good news is that there are multiple combinations that will work if the net result is to give the motor the air and fuel it needs at the various operating conditions of air and engine temperature, etc.

[02Ls1]

Look at ALL of the spark/timing tables and ALL of the air flow and ALL the PID tables in my tune for ideas for your tune. Let me know if you have any questions.

I will take a look and try it and copare it to my file to see what changes can i do to make it idle better.

[02Ls1]

Half is going to make it worse. Spark is the #1 thing for idle control and not enough will cause over and undershoot.

I bump the timing on the underspeed and overspeed, i still need more work.

How the timing should look in the scanner at idle? When it the overspeed and underspeed was half down i had almost a smooth line on the chart for the timing, Now is going up and down. What should realy look like?

[Maxwell Power]

what throttle body are you running?

On BIG cam cars, I start by opening up the idle bleed hole in the butterfly if we're using the stock throttle body. Some people think that's cheating, but the idea is to get the IAC in its most efficient range. At the far end of the open scale, changes in position don't have as large of an effect on airflow so idle control can be a bit unsteady. By opening the hole, you get more base airflow and bring IAC down into it's most effective range.

[WS6FirebirdTA00]

It should be going up and down to control the idle, spark control is where it is at, IAC is too slow.

[02Ls1]

What a good timing at idle? Mine is jumping from 26 to 36 some what around that.

[WS6FirebirdTA00]

It is all off your base spark table, looks like you are commanding 30 deg which I think is too high. I would drop that back in the 20s, try around 24 and play with it.