GTO Terrible startup, oscillating. H/C/I Headers.

[1BadSlug]

05 GTO 6.0L E40
Has a problem finding idle, would like some input on finding/repairing this issues.
Car runs and drivers excellant, its just initial startup. After 25 seconds in the attached log it idles like a champ.

Any questions please ask.
attached is the tune and the startup log.V1.00 Original Modded Tune.hptgto idle.hpl

[kevin87turbot]

You're running a few degrees too much ignition timing at idle and overall timing as well.
The Startup Airflow table was maxed out for some reason. The VE table was actually a little higher than stock at lower rpm, which sure doesn't seem correct.
I've made a few small tweaks and disabled the VE. Try this one and see how it does. I just tuned a similar combo a few weeks ago.

V1.00 Original Modded Tunekwmod2.hpt

[jpierro79]

heres what happens your trying to tune VVE o2 trims off stock settings and with headers the collector tends to recirculate exhaust at low rpm on front o2. Set starting with 700 in bank 1 and bank 2 o2 then each air zone down 50 mv till you hit stock. Then try to redo your trims. You've gone from a 2 inch opening to more than likely a 4 inch square is where your front o2's are sitting. By setting the transition higher at low airflow zones helps keep the trims inline. In truth headers means you NEED A WIDEBAND! hate to say it but its true. The ltft stft will ALWAYS take fuel out with headers as they do not react fast enough and are truthfully never placed in right position to work with factory ecu caibration. try this is might help dial in low rpm lean. You really need a wideband though.V1.00 Original Modded Tunekwmod header o2 adjust.hpt you will still have to tune it but start by setting youre vve back to complete stock. and you can never trust stock o2 for WOT

[1BadSlug]

You're running a few degrees too much ignition timing at idle and overall timing as well.
The Startup Airflow table was maxed out for some reason. The VE table was actually a little higher than stock at lower rpm, which sure doesn't seem correct.
I've made a few small tweaks and disabled the VE. Try this one and see how it does. I just tuned a similar combo a few weeks ago.

V1.00 Original Modded Tunekwmod2.hpt

Excellant, Thank you both for your feed back. Ill be sure to try this.

Also to add, would you guys agree the power enrichment ramp in rate should be increased from 1.0000 to 1.3000? This wouldn't harm anything, just increase the speed it enriches fueling?!?


Kevin, I don't see where you decreased timing? Maybe in the mid and top end...At 20% cylinder volume, 1000RPM if anything it looks to be increased. Please have another look at the file you uploaded. Let me know.
Thanks again.
Cheers.

[jpierro79]

by decreasing timing all your doing is burning fuel later and forcing more mixture later into the lt headers. I run a 2013zl1 lt headers with stock 02 no base timing adjustments for idle and have 18 percent overdrive along with rotofab intake rocker upgrades and fpcm programming along with x pipe and a few other mods and did not have to touch timing to get a correct smooth idle the VVE and MAF have to be correlated to function so that they will read accurate air flow. This is smooth idle only cams require timing change at idle. balance out your blended vve stop using maf it will run like stock sware im goin to start making videos on how my car run ice cold just to prove vve tuning. Yes there are some o2 offsets to be changed at low airflow modes. If you want it right pm me. theres a lot you havent corrected even down to post catalyst o2 testing. Im not trying to belittle you but pass on knowledge. Up to you?? PM me i will even contact via phone as o do this cause i love not try to swindle your pockets. i could very easliy e tune but i have little time left so i do it cause i love it