Big Cam Idle Issues

I'm working through a tune and am having the following issues:

1. In OL and CL the car idles fine. Once CL occurs and I blip the throttle it hangs around 1200rpm
2. Once CL occurs and I attempt to put the car in R, it will die unless I hold throttle
3. Is it normal for LTFT to creep to negative for 1sec and return to normal?

Any feedback would be greatly appreciated.

Log files attached

6.0L
FAST 102
42lb injectors
SNS Stage 3
3600 stall
Stg 2 243's

Only DTC is due to MAF being turned off.Attachment 83492Attachment 83493Attachment 83494

Im mobile atm so cant view logs until tonight but sounds like you need to get your base running airflow dialed in - the vehicle will always require more airflow in gear than park/neutral... the hanging idle I'd re evaluate once you get the idle airflow dialed in - throttle cracker is normally the culprit for a hanging idle but usually during coastdown but I guess it's possible
Define normal for fuel trims - i always shoot for a -5 average during summer so when cooler weather hits itll still be ok

No worries! Let me know when you can. I have about 10% more idle air in Gear than P/N. I have the cracker disabled. As of now I haven?t driven the car.

I can post the tune as well.

I'd almost say because it runs and idles just stop there and go straight to fixing the airflow model. This was it will make idle tuning that much faster.

Forget about closed loop right now and go open loop speed density to fix the VE table to get fueling dialed in with a wideband. Enable closed loop again once the VE is corrected.

yes, always post the tune so others can see as well but yeah the fueling is off quite a bit - it just pegs rich (ltft stops at -16% and stft peg -40) and resets so like 5fdp stated get the fueling inline - your going to need to remove fuel and maybe add like 10% more air for in gear idle airflow and see if it gets better putting it into gear

Quote:

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Originally Posted by TCSS07

yes, always post the tune so others can see as well but yeah the fueling is off quite a bit - it just pegs rich (ltft stops at -16% and stft peg -40) and resets so like 5fdp stated get the fueling inline - your going to need to remove fuel and maybe add like 10% more air for in gear idle airflow and see if it gets better putting it into gear

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TCSS07 Thanks!

Here's the tune for reference:Attachment 83538

You have waaaay too much under/over speed spark correction and looks like a pretty big cam (little or no vacuum) or a major air leak. Recommend putting spark correction back to stock (or even zero it) to see if it idles. If it does not, then your air models and/or PID settings are way off as well. One thing to remember is if you have the air (PID, VE and MAF) close, then your idle spark should be hovering around your desired which is 18 degrees...sometimes you have 18-20 but your rpms are well below the desired of 975 rpm which means you have driven the underspeed to its max....of 18 degrees! so you are starting with little or no timing which mean it is pulling it down to lower idle rpm (over desired)....

Also at operating temp you are looking for the IAC counts to be at 50-80 steps/<.7 vdc.....and enough room at cold to not not max out count (310) during cold start.

Also ETC (Electronc Throttle Control) plays no role in an IAC fitted platform so changing it is not required....the effective area vs IAC steps will determine the scalar for the IAC. What size throttle body do you have?

Use these channels, check for vacuum/air leaks firs, dial in the MAF and VE to idle rpm and even a little below, then go for the idle.

What cam are you running for the records?

Ed M

Ed,

Thanks for your insight and direction.

Cam: Tick SNS Stg 3
TB: 102mm

I'll work on the tune and report back.

This cam is similar to mine but different platform.
How do you go about getting a good idle. Surely this cam, you cant really depend on the wideband or O2s at idle.

How do you avoid cam reversion and split trims at idle?

Needs more air and don?t count on 02 sensors making the correct fuel adjustment

Quote:

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Originally Posted by Ben Charles

Needs more air and don?t count on 02 sensors making the correct fuel adjustment

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Yea kinda gotta give lt what it wants ..
I did away with O2s for now snd kinda like it