After Header Modifications? And O2 Question

[Dale]

Just got headers installed on my beast. Havent scanned it yet, but I was wondering what should I see/expect?

Anyone able to adjust more timing into the motor, or have to pull some away?


Also, is Bank2 o2, is that to be on the side with even cylinders? I think I may have my sensors wired backwards

[cmitchell17]

Im about to get some headers too on my 5.3.

Im still trying to figure out what I need to do becuase I wont have a wideband.

All Ive heard is that LT headers usally show a 5-8% increase in the midrange and not much up top. And they make the 4200-5500 knock range knock a lot more. Im going to take my timing almost down to stock levels and increase my VE table a little before I put them on and see what happends.

[BlackGMC]

I just installed some Hooker headers LTs and custom Mandrel exhaust (PICS)on my 4.8. I started over from scratch (Stock VE) and blended my Optimum Timing table to the High Octance table. I added 15% to the VE table and 40% to the ETC as described in the tutorial. Did a logg and this is what it looked like.



Next I applied the BEN correction @ 75%, then I set the ETC back to stock and relogged and this is what it looked like.

[Dale]

So it does have some effect on the knock system. Guess I will just have to throw what I have out the door and start on it again.

Thanks for info!

[BlackGMC]

I got very little knock in a few cells, it was like < .05..

[cmitchell17]

Im also running a blend of my high octane table.
How do you like it.

Im starting to think ill take my timing down to almost stock levels in the lower g/cyl range. The more timing dosent seem to help part thorttle.

I think gm would have put about the best timing in too it at light throttle since theres not that much chance of detonation.

[BlackGMC]

Im also running a blend of my high octane table.
How do you like it.

Im starting to think ill take my timing down to almost stock levels in the lower g/cyl range. The more timing dosent seem to help part thorttle.

I think gm would have put about the best timing in too it at light throttle since theres not that much chance of detonation.

i am also thinking of putting mine back to stock and well maybe half of the difference, I still want a little increase. But I am going use B5908 to add my timing for PE.... I am going to the track this weekend to start some timing tuning then off to the dyno for some more tweaking.....

[cmitchell17]

Yeah once you blend your timing youll have to figure out what to do with the Fuel mixture spark correction.

I lowered mine to about 0-3 degrees and it looks good.

I set it to add no timing in the 3800-5000 range and then 1 or 2 degrees up from there. So the timing will drop 1-3 degrees at peak torque. I get knock on anything but 93.

With holiday shipping I dont think ill get my headers untill after new years.

[BlackGMC]

What kind did you go with? Do you ever go to www.PerformanceTrucks.net if not you might want to check it out!

[Dale]

Well, I drove it around today but still havent scanned it. I was still working on fuel, timing anyway. Was just wondering what I might see.

I have noticed that it doesnt want to idle for crap and when coming to a light it will die. Could it be that my old exhaust system was so restrictive it created back pressure that would keep the motor running? Guessing I will have to now look at the throttle follower settings and adjust them? Or just a new idle refiag?