Need help with getting the idle right.

[haulinit]

I'm having a heck of a time trying to get my idle corrected. I have been trying to compare between the stock tune and the 02 x van tune but as you know the 0411 has just a few more options:help2:. The truck pops off nicely but then starts stumbling and usually throws a p0300 code, it then starts smoothing out. I have modded the b4304 table by adding 15% more air that seemed to help but hasn't really solved my problem. I'm lost I don't know where to go. I have read the idle tuning tutorials but still have no idea, most of the stuff I have found are related to fixing idle swings and surges. Once the truck has warmed up it doesn't do it as bad. I don't know how the cam is affecting this either, its not like the cam has a choppy idle. It idled fine with the black box. Sorry for the long post :fluffy:. I would appreciate it if someone would point me in the correct direction.

Thanks
Shawn

[odd boy]

what mods does it have?

[Taz]

Hello Shawn,

Tuning a consistent idle in a modified vehicle can be very challenging - it’s an area that doesn’t come naturally to me - and I sometimes struggle with this part of a tune. The idle thread by WeathermanShawn is an absolutely excellent resource to help understand “how things work”.

The ZZ4 cam you are using is not that aggressive - if memory serves it’s around a 208 / 221 grind on 114 degree lobe separation angle.

I would recommend reading the thread below - regarding V8 Vortec camshaft position retard - this will affect the idle quality.

http://forum.efilive.com/showthread.php?14762-Camshaft-Position-Retard.


After confirming your camshaft / distributor is properly synchronized, I would then recommend the following:

begin with a completely “stock” tune
in B4603 (Desired Idle Speeds) add 250 RPM to the in gear idle, and 200 RPM to the park / neutral idle
this will help “stabilize” the idle, and make the tuning process less frustrating
after you have tuned your idle, these idle speeds could be reduced somewhat to give you a more “muscle car” idle sound

Then apply the techniques as described in the idle tuning thread by WeathermanShawn (and associated threads). Approach this process slowly and methodically, and attempt to only make one change at a time - to evaluate the effect of the change (if any) on the idle quality.


Regards,
Taz

[Taz]

My apologies … I forgot to comment on the misfire issue.

In the short term, until you get the tune / idle sorted out, try the following:

set C5602, C5603, C5604 - to 140 degrees F
set C5606 - to 950 RPM

This will “soften” the misfire detect protocol when the engine is cold or at idle. This may help separate a true misfire issue from mere camshaft effect - at idle or when the engine is cold.


Regards,
Taz

[haulinit]

what mods does it have?

ZZ4 cam shaft 208/221 on 114 lsa, roller rockers, shorty headers, 0411 PCM swap and other small bolt ons.

[haulinit]

Taz, last time I checked my timing it was set correctly at +2* from zero at 1500 rpm. I will have to try your steps and some more reading thanks. I was getting frustrated and not seeing the results I wanted.

Thanks for the helping hand
Shawn

[haulinit]

After some testing If I shut cylinder 4's injector off it made no difference in how the engine was running, but once we took the injectors out cylinder number 6 was not working :wtf1:. I swapped out the injector, but now it wont hold FP it worked just fine before we swapped the injector. The truck now runs better but im still getting a miss fire code of P0300 and a lean bank 1 code. I also reset my CMP retard, it was boincing around -4 to -3, spec is +/- 2 from zero.

What would have caused shutting #4 off and not making a difference and it really being injector #6?

I'm attaching a snap shot of my LTFT's im assuming that its telling me that im pretty lean.

http://s419.photobucket.com/albums/pp278/squeaksmith/?action=view&current=LTFT.jpg