Still Working on a "Smokeless" tune....

[GMPX]

I need some help with pilot. I have reduced the pilot duration table, but only smoothed the pilot timing table. I'm really not sure how much to reduce the pilot duration and timing. Since I have reduced the pilot duration 10%, should I reduce the pilot timing table roughly the same amount?

Just my opinion (keeping in mind I don't tune every day), but I would suggest not changing the pulse tables, instead change the commanded mm3 amount for all your injection events. The ECM keeps track of commanded mm3 rates for all the injection events, if you zero the commanded mm3 then it knows there was no fuel injected for that event, if you still have say 15mm3 commanded but 0uS pulse time, it still thinks there was 15mm3 of fuel injected.

[DoghouseDiesel]

In most cases you DO NOT want to reduce the quantity of the pilot, you need to adjust the timing of it.

With larger injectors or higher commanded fuel, you often need to INCREASE the pilot quantity.

Reducing pilot events doesn't reduce smoke, it'll increase it in the daily driving ranges and you'll see higher EGT's as well.

[TexasCummins]

Subscribed.

[TexasCummins]

I mainly use {F0502} to control smoke down low as that's when my tunes seem to smoke or haze the most during take-off, low load acceleration and when it's in fourth gear locked up between 48-65mph.

I've also messed with the pilot quantities and timing to get the turbo spooling better in those situations, once I hit 10psi+ it mostly clears up.

[CIDRAUGHN]

In most cases you DO NOT want to reduce the quantity of the pilot, you need to adjust the timing of it.

With larger injectors or higher commanded fuel, you often need to INCREASE the pilot quantity.

Reducing pilot events doesn't reduce smoke, it'll increase it in the daily driving ranges and you'll see higher EGT's as well.

So you are saying to slightly increase pilot. Tell me if I am thinking correctly here but would I want to retard the main timing then to keep from having so much fuel put in BTDC? I have found my max timing limit for the uS that I am currently running on main injection. I am assuming you would retard the pilot timing then as well? Im getting pretty close to making a smokeless tune, but Im very interested in cleaning it up that much further, and possibly making it stronger as well.

[Dmaxink]

I have not had luck with increasing pilot on any of our big and some BIG injector trucks...our most positive results were from decreasing. Considering main uS has to be pulled for big sticks, so does the pilot in my experience. If a 245uS pilot before was ok, lets put 100s on it.and that becomes a 490uS basically...that's a big squirt...we lowered the pilot uS which in turn lowered the timing, and then went about our business and this has worked best for us.... maybe I have freak trucks ;-)

Pilot timing is a necessity to be modified once the main has been advanced...

[CIDRAUGHN]

Dmaxink, that has been my experience as well with 100% overs. I am about to throw in some larger ones and I was hoping to clarify that a little before I start tuning them in.

[2007 5.9]

I agree..I've seen better results from decreasing pilot timing and amount....

Not that I think your wrong Rich, but my results are not the same. And I've spent lots if time with 2 specific trucks that are running 70lpm and 90lpm injectors respectively.

Maybe ill try it in my personal truck and see if my results differ.

[Dmaxink]

Step 1.)

120,000,000
-----------= uSec/cycle
RPM

Step 2.)
add pilot pulse and main pulse then

pilot uS+Main uS
---------------= X*720(which is a full crank revolution)= Total Duration (on time)
uSec/Cycle

The total duration can be split divided by 2 or whatever you wish (50% timing)... This is how timing works in case anyone was wondering past the calculator :-)

EDIT: If you are using a post event, make sure you add the pulse of that event to Step#2.

Try this formula out on a 5.9 cummins running 140mm3@2600RPM and 23k PSI.. Stock timing comes out to start the injection around 50%BTDC afterall... The Main uS is the "power" shot so to speak... this is why in upper rpms many folks will rid pilot and post to utilize the Timing of the "power shot"..

LAST EDIT I PROMISE :-)
I hear some guys say "OMG 58* of PiLoTtT??" Well actually when we think timing we are thinking main timing which is dealing with main (big pulse) on time..so say you used the calculator and your working with 40* total on time with a 50% split (50btdc and 50%atdc which is 20* in tune tool).. Ok that was 40* total ON TIME (BIG PULSE)... the 58* of pilot is actually just saying its 58* away from the main, with a 245uS Pilot at 2600RPM, that is actually only 3* of pilot on time which a small amount... So there is another way of looking at it... Hope im not running everyone in circles...alot of times the way things make sense to me or a little wild. lol

[DoghouseDiesel]

It's like anything else, each truck is a different combination of parts.

This is one reason I don't do the mail order tunes or specific tuning advice.

When it comes to the smoke output and engine noise, the pilot is critical. It's a lot less so in the upper RPM ranges when all you're looking for is max power.

Over the last week, I've been doing nothing but testing different pilot combinations in different situations, specifically for smoke control, engine noise and throttle response.

If folks aren't tuning that pilot shot, you're missing out on a lot of untapped drivability.