tuning for opacity

[6.6l eater]

I was wondering if anyone has any tips for tuning for opacity snap throttle test. I live in az and have to go through this every year. Truck has always been pretty dirty since the smarty and can't figure what i can change to blow clean.

Mods
bbi stage 1 injectors
80% over II cp3
dual disc
afe cold air and air horn
63/68 .7ar with spool valve

I took a log of snap test reads 68% load and commanding 69mm3 fuel. What are some tips to change to make this right so I can pass smog? The tune I went through with this morning is basically stock with pedal map backed down to 100mm3.

[Jim P]

Move outside of the valley where smog test isn?t required? Lol. I dunno the requirements for smog test other than it must meet the standards for the year manufactured. Stock 5.9 will blow a puff of black smoke snapping the throttle like that. My 12 valve has always done it and my previous 3rd gen did it stock.

[Jim P]

Reduce your max commanded mm3 to half of stock maybe?

[Dom_c13b]

Timing will help a lot. You need to drop your timing into the ATDC range. try -3 to -6* of timing in that snap range. That will keep the smoke to a minimum and also help spool the turbo. Negative timing is a huge help in getting these trucks to drive clean.

[6.6l eater]

I wish Jim p. Lol. The spec for opacity for my truck is 40, I blew a 52. Are you talking about pedal map in half?

Dom I thought I would need more advance timing? It's not on rollers, neutral/park 3 sec 100% tps then back to idle, 3x. With the turbo and spool valve it will free Rev to 8psi.

[Dom_c13b]

At low load and rpm ATDC timing will run cleaner. On the top end you need BTDC timing to keep smoke down but not at idle and snap throttle..

[6.6l eater]

Hmm.... It's an early 03. Maybe reduce pilot pw or pilot timing?

[Dom_c13b]

I run 18* btdc Pilot at idle and low load on 03/04.

[Jim P]

I wish Jim p. Lol. The spec for opacity for my truck is 40, I blew a 52. Are you talking about pedal map in half?

Dom I thought I would need more advance timing? It's not on rollers, neutral/park 3 sec 100% tps then back to idle, 3x. With the turbo and spool valve it will free Rev to 8psi.

The White Mountains is a beautiful location to live and doesn?t get anywhere near as ridiculously hot as the valley, plus no smog check lol. But yea could try reducing the throttle to fuel in half, limit the max fuel output and like Dom said, reduce timing, timing does play a large role in smoke. With post I?ve never noticed any real difference between stock post and no post but if using post and tuned correctly it can help reduce smoke, tuned incorrectly it can easily create more smoke. Only need to do it for the time it takes to do the smog check.

[Orange Stroker]

Negative timing in snap area will help some. Higher rp in snap area usually helps as well as I'd play around in the Boost limit table and start somewhere in the 30-50mm3 at the botom of the map depending on your pw table and phase up as you go up towards full boost. I've had most success with limiting fuel based on boost on the bottom end for cleaning up trucks. That table is extremely helpful. Here is a screen shot of how I did one on a truck with 100% injectors and a peak pw table of 1400us and the rest of the table cut by 25% linear to the 1400us. Hope this helps

[6.6l eater]

Thanks orange, I'll make some changes tonight or tomorrow and see what happens

[6.6l eater]

Ok here is my adjustments I made. I adjusted 3 tables in the notes section, all in the 30-65mm fuel range and with pedal map at 100mm. I can't load tonight, tablet battery is dead. I'll load it tomorrow and see if it will work. Am I on the right track or do I need to rethink this? Just a quick question, does table 7420, pilot timing, I assume it is based off of a 20* main injection off set? Pilot in the log is at almost 50* in the snap area. Thanks for all your help guys.

[Dom_c13b]

TIM 125's 1600uS Boost Fueling Adjustments.hpt

Take a look at this file. This is a 2003 truck with a stock turbo and 60%over injectors. Truck is relatively smoke free. When looking at your file, your boost fueling table is going to hurt you if your truck will in fact make 8psi on a free rev. If that's the case it will be fueling way harder than you want it to, causing smoke.
Also take not of the timing tables in this tune and the ATDC timing.

[6.6l eater]

Thanks Dom. I'll have a look at it tonight.

[6.6l eater]

I think I finally got where I need to be, except now have a stutter during snap throttle in neutral 2200-2500 rpm. I don't think it's timing pop and it's not showing up on the log. Any ideas where I need to look? Here is what I'm working with. I should mention I only noticed the stutter when I disabled misfire correction.

[Dom_c13b]

Did you adjust the pilot correction tables? That is where the pop usually comes from on these trucks.

[6.6l eater]

I did not adjust those. I'll have a look. Thanks Dom