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 :frown:

[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 (http://s27.photobucket.com/albums/c185/BlackGMC/Truck/Exhaust/))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.

http://i27.photobucket.com/albums/c185/BlackGMC/Truck/Tuning/Log1.jpg

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

http://i27.photobucket.com/albums/c185/BlackGMC/Truck/Tuning/Log2.jpg

[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?

[BlackGMC]

It just needs time for the trims to learn, but definately needs some tuning... IMO unless you have a cam I would not mess with the idle stuff until after you tuned the VE table, you might needs to add a degree or two of timing in the idle regions..

[Dale]

Well I had been messing with the idle because I didnt know I had a bad sensor. I have correct sensor on order and will fix that after its in. But I had it working before and would not stall. Now it stalls after new exhaust.

[cmitchell17]

How does it run with the new headers?

[Dale]

Feels a little faster reving. Maybe a little more pull power.

Just installed new IAC, EGR, and found 2 of my spark plug wires are damaged already. Swapped my O2 wires to what I think is correct sides. So fixing all that then we will log it and see what she does.

[cmitchell17]

I just put mine on and it runs fine but dosent have any more power.

Im going to add a little to the ve table.

I get about 1% fuel trims and about -1,-3% at closed throttle.

I also get no knock according to my knock sensors but since the headers are so loud and noisy I can hear knock anymore.

[cmitchell17]

Comparing my old logs with the header logs maf airflow is lower(20-40g/sec) with the headers. But delievered torque is higher(20ft.lbs.) and it looks like MAP pressure is also higher with the headers.

[cmitchell17]

Here are my logs:

[Dale]

I had to remove fuel on mine (main ve). Still slowly removing.

I noticed my Kpa is higher (same as you found)

I'm still working on my stalling issue for when I come up to a light and push in the clutch.

I'm not sure my gains were worth the cost :shrugs:

[BlackGMC]

I would suggest both of you AutoVE again, and tune your MAF. I noticed quite a bit of difference when I installed mine. However I decided to remain in OLSD because I was having a hard time dialing in my MAF. My truck runs totally different now. When I first installed mine I had a few exhaust leaks that really killed my tune, but now it is runing great!!! Also CMitchell17, you need to remove a couple of PIDs from your list to get better resolution.... What year and size motor are you running?

[cmitchell17]

A 2000 Ext cab 5.3.

Sorry I dont have a wideband, and I know I should get one.

I have 24 PID so it should be faster right? Its in the fast scan mode I think?

I don't see how you would have to take away fuel, shouldent headers add volumetric effiency?

Im going to take my y-pipe tommarow and reinstall it to make it fit better along with a little o2 safe silicone.

Can you tune the sensor for its new position in the exhaust? Becuase its now probably about 6inches away from the stock O2 location.

[BlackGMC]

When I put in my headers I completely redid my exhaust, I had the WB located after the Y-pipe, which gave me some rather strange readings also mixed with a few exhaust leaks it really made it hard to tune. I removed all my exhaust and check all the welds (magnaflow Y-pipe weld cracked) and put in some new manifold gaskets. I also moved the WB right after the header collector. Works much better there!!! Anyways the values in my VE table increased after the headers....

[cmitchell17]

Why would you need to tune the maf. I thought you only needed it if changed to a aftermarket maf or moved it in some way.

[BlackGMC]

the maf inputs in the airflow calculation, especially after 4000rpm (if you have not changed that parameter)... So it directly affects your AFR...

B0120 is the threshold for airflow calculation... Above this value the MAF is directly responsible for the airflow calculation, below it is a mixture of MAF and VE....

IMO you should start from the begining... The following are small steps, each one builds off the other... If the previous is wrong, then the next will be off...

1. AutoVE with PE disabled, filter on 95 Kpa <
2. AutoVE with PE enabled, mainly just WOT passes, filter on 95 Kpa >
3. Log Dynair vs MAF freq to get a MAF baseline. Mixture of regular driving and WOT passes
4. Enable MAF and use BEN correction factors to fine tune it.

any other questions?

[cmitchell17]

I wish I could do auto ve but I don't have a wideband.:mad:

[BlackGMC]

where are you located?

[cmitchell17]

north florida

[BlackGMC]

ahhh, I was going to say if you were local I would let you borrow mine for a little bit.

[cmitchell17]

Thanks for the offer though. Ill probably end up buying one soon.

[cmitchell17]

Ive got everything back on after putting copper sensor safe gasket on the clamps.

I guess everything is screwed up the fuel trims were all over the place.

Im going to run it in open loop and see how it feels although it feels normal right now just fuel trims are all over the place.

[cmitchell17]

These are also long term fuel trims. I forgot to log short term fuel trims.

[Dale]

I didnt get any notices that there were new responses tell now. WTF?

Anyway, found out my maf was dirty due to oiled air filters, got it cleaned. Got my speedo kinda working(it was wired wrong).

Just waiting for some dry pavement to go re-scan mine. I know my ve is going to be WAY off due to maf signals.

[cmitchell17]

Yeah ive cleaned my maf before.

I tunred my LTFC and STFC off so ill go see how it runs.