Stock TBI 350 with Headers

[Kitch]

​​As the heading says, I have basically a stock 94 TBI 350 in a G20 conversion van, but I have fitted Headman 6941 (yep, had to cut off the air injection tubes) ultra duty HPC coated full length headers to it and a free flowing 3" single exhaust system.
I'd appreciate any advice on some of the items I could look at changing in my BDTZ bin $OD PCM to improve of the stock values that it currently has.
I think I read somewhere there is a time delay I can change to compensate for the fact that the new heated narrow band O2 sensor has moved from near the engine to down past the header collector, does that sound right?

Dave W, I've attached my .bin for your library.

[Kitch]

The "similar threads" links that appeared on the bottom of this post helped with some info. I looked a my "Integrator Delay vs Airflow" settings, the values in there seemed quite a bit larger compared to the only other ones I've seen in this post:
http://www.gearhead-efi.com/Fuel-Inj...ng-for-headers

What should the values be approximately?
Is this one of the first things I should look at changing or are there more important items I should address first?

[dave w]

​​As the heading says, I have basically a stock 94 TBI 350 in a G20 conversion van, but I have fitted Headman 6941 (yep, had to cut off the air injection tubes) ultra duty HPC coated full length headers to it and a free flowing 3" single exhaust system.
I'd appreciate any advice on some of the items I could look at changing in my BDTZ bin $OD PCM to improve of the stock values that it currently has.
I think I read somewhere there is a time delay I can change to compensate for the fact that the new heated narrow band O2 sensor has moved from near the engine to down past the header collector, does that sound right?

Dave W, I've attached my .bin for your library.

Thanks for posting the BDTZ.bin file. It's $OD

dave w

[Roadknee]

The "similar threads" links that appeared on the bottom of this post helped with some info. I looked a my "Integrator Delay vs Airflow" settings, the values in there seemed quite a bit larger compared to the only other ones I've seen in this post:
http://www.gearhead-efi.com/Fuel-Inj...ng-for-headers

What should the values be approximately?
Is this one of the first things I should look at changing or are there more important items I should address first?

Like Dave mentioned, you need to use a $0D XDF to read this bin. In the pic above you were using something else, and that's why the numbers are so high.

For your longtubes, I'd recommend 750 at zero, draw a straight line to 350 at 64, and draw another straight line to 150 at 128. That should get you in the ballpark.

If you experience any part throttle surge the other fuel trim parameters will need some work. Visit BLG355's Idle BLM thread for more info.

[Kitch]

Thanks for the reply, I should have figured that out myself.
When my friend first set me up for data logging he wasn't sure what the PCM's MASK ID was so he wen't with a $OE XDF/ADX. Once I managed to get my actual .bin file I was able to read the ID so I had been using a $OD XDF but wen't back to the $OE to see what some of the difference were and forgot that I had done that when I posted the screenshot.
750 at zero makes sense but you have lost me with "draw a straight straight line to 350 at 64, and draw another straight line to 150 at 128" could you expand on your description a bit for me?

Screen shot is now with $OD XDF :-)

[Roadknee]

750 at zero makes sense but you have lost me with "draw a straight straight line to 350 at 64, and draw another straight line to 150 at 128" could you expand on your description a bit for me?

Input 750 ms at zero airflow and 350 ms at 64 airflow and use the graphing function to draw a straight line between the two. Do the same between 350 at 64 and 150 at 128. Your table will look like this.

0 750
16 650
32 550
48 450
64 350
80 300
96 250
112 200
128 150

[Kitch]

Thanks for showing it in table form, I get it now. Start at 750ms then decrease in 100ms steps from 0 to 64 and then 50ms steps from 64 to 128.

After a test drive, what visible changes should I be looking for in the TunerRT logs to indicate it's made an impovement? Less swing in the closed loop narrow band O2 sensor output and my wide band fluctuating less?

[Fast355]

Input 750 ms at zero airflow and 350 ms at 64 airflow and use the graphing function to draw a straight line between the two. Do the same between 350 at 64 and 150 at 128. Your table will look like this.

0 750
16 650
32 550
48 450
64 350
80 300
96 250
112 200
128 150

That is exactly opposite of how I tune that table. Headers naturally make the 02 sensors cycle richer than stock at low flows and the scavenging action leans out the mid-upper flow range. I don't go under about 350mv or above 650 on that table.

0 450
16 475
32 500
48 525
64 550
80 575
96 600
112 625
128 650

My way runs a little fatter but also gives more torque at part-throttle requiring fewer power enrichment events. Being able to accelerate without having to floor it and kickdown saves a ton of fuel in something as heavy as a van.

My Thorley headers designed as a replacement for the manifolds of my Express van are designed and have a CARB EO# for use in California with the stock tune set at 450mv across the board. 02s are roughly in the stock locations though.

[brian617]

Fast, that table is airflow vs msec, not mv.

[Fast355]

Fast, that table is airflow vs msec, not mv.

Sorry I thought that was the mv table. On a G-Van (The 95 I pulled my 7427 and BJYN memcal out of) I would not expect the delays needing much change. The 02 sensor on the newer G-vans from the factory is after the Y merge right before the cat. If anything the delays need to be shorter than stock because the 02 will be closer to the cylinder head if it is in a header collector. I had Thorley Tri-Ys, Vortecs, mild 114 lsa cam and did not experience any surging due to 02 placement.

[PJG1173]

I take it this is another setting that just needs to be played with? I know when I put long tubes on my truck the NB went all out of wack since it moved about 16" or so from the stock location.

[Fast355]

I take it this is another setting that just needs to be played with? I know when I put long tubes on my truck the NB went all out of wack since it moved about 16" or so from the motor.

Seems like it! I have also had to play with this setting when I switched intakes from dual to single plane and again when I went to TPI.

Playing with proportional duration can also help in some situations.

[Kitch]

I've made the changes Roadknee suggested, burn't a new chip, installed it and took the van for a test drive. Once the vans warmed up low speed cruising has a noticeable surge, more so than before and the way the O2 sensor reacts on the dashboard display has changed.
Could there be some other things going on I need to address before changing the Integrator delay vs airflow?
I've attached the .bin, xdf and a xdl log of my last test drive if anyone would like to take a look. The first three quarters of the log is mostly motor way running, idle and low speed driving are in the final quarter.

[Fast355]

I've made the changes Roadknee suggested, burn't a new chip, installed it and took the van for a test drive. Once the vans warmed up low speed cruising has a noticeable surge, more so than before and the way the O2 sensor reacts on the dashboard display has changed.
Could there be some other things going on I need to address before changing the Integrator delay vs airflow?
I've attached the .bin, xdf and a xdl log of my last test drive if anyone would like to take a look. The first three quarters of the log is mostly motor way running, idle and low speed driving are in the final quarter.

Try putting the integrator delay back stock and putting my 02 MV target values in the lean/rich/median 02 sensor values.

[dave w]

Attached is a screen shot of the BLM averages from the data log posted.

dave w