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Discussion Starter #1
Maybe I am thinking wrong.

My mods are listed in my sig line. I have adjusted the afc with shop air and have it set for full foot travel at 35 psi. My smoke screw is in some (about 1/8" of thread beyond nut on outside) as it seems to like a litttle more fuel on the bottom, clears up when boost comes on. The truck runs great if I give it not quite full throttle with just haze. Boost runs up to about 37 fast and egt's are manegable. Here is my question - if I WOT from the start, I can roll coal all the way and egt's will spike up to 1600 if I let them. Is this just typical of a mack plug mod? I have no problem driving accordingly and even rolling coal, the truck is rippin. Are my expectations unrealistic or should I be able to get this thing to runn WOT without smoke and temps?
 

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sounds like you need to back off on the preboost and transient fueling a bit (preboost screw and starwheel). or just drive it the way it is!
 

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Discussion Starter #3 (Edited)
I had the star wheel backed off completely where the afc foot would achieve full travel at about 18 psi and it did the same thing. I have had the preboost screw all the way out to where it just barely touched the plunger and although it didn't puff smoke as bad on take off, it wasn't as quick to spool up either.

I am actually ok with driving it like it is but was just wondering if this is what others have found or if it is abnormal and I need to keep looking.

I have pressurized the system and I have no air leaks so that has been ruled out.

Any other ideas?
 

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you want to tighten up the starwheel, not loosen it, to decrease transient fueling (fuel VS boost). you could even try different springs to try and get it to your liking

Try sliding the AFC housing all the way rearward. this will also decrease preboost and transient fueling without changing the spring rate. If its pretty lean on the bottom end and spools slow, you can compensate by tightening up the preboost screw a bit.
 

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Discussion Starter #5
I have the afc spring kit in it with the heavy spring and the star wheel is currently cranked tight enough to take 35psi to move the foot full travel, much more and the spring will be completely compressed. If I go any tighter I would assume that stopping the foot from achieving full travel is defeating the purpose of achieving full rack travel with the mack plug, no?
 

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try the light spring


sounds like you need to do some more tuning bud
 

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yea, lighter spring first. then back the preboost screw out til it barely touches, then slide the afc housing back til you have NO smoke and it spools a little slow. then use your preboost screw to slowly add more fuel (by ajusting it in) until you get good low end fuel. then ajust the starwheel for the fuel curve you need.
 
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Discussion Starter #8
So where do I start with the star wheel set at for this process?

Is sliding the afc housing back restricting rack travel?
 

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So where do I start with the star wheel set at for this process?

Is sliding the afc housing back restricting rack travel?
Start with just a little pressure on the spring, easy to set it with the afc off the pump.

if the afc is modded for full travel then sliding the housing back wont cause any limitation of full rack travel, just better pre-boost smoke control
 

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Discussion Starter #10
the afc is modded for full travel. I will start with the star wheel just a couple turns off full out and see what happens. Report tomarrow, thanks.
 

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Discussion Starter #11
OK, slid the afc back some (can't go too far or the throttle linkage or something does wierd **** and you can floor it with no response) and got just dark haze when flooring it but still have a heavy puff when you first take off (pre-boost). I have adjusted the star wheel to about half on the clicks and haven't seen a change. Should I keep tightening the spring more? I have to be getting close to maximim on that long spring.

Could this be a result of besides grinding the barrel on the arm I also ground some off the foot (about 1/8") and made it flat instead of at that angle. Would this cause heavy fueling on pre-boost?
 

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^^^^^^^^^^ that was a bad move



that is EXACTLY your problem......
 

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Could this be a result of besides grinding the barrel on the arm I also ground some off the foot (about 1/8") and made it flat instead of at that angle. Would this cause heavy fueling on pre-boost?
 
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Discussion Starter #14
^^^^^^^^^^ that was a bad move



that is EXACTLY your problem......



Yup, did it when I was new to the truck and reading all the BS people say. Know now that it was a bad move, will find a stock arm somewhere and just grind the barrel this time.

Thanks for all the help (and patience) guys.
 

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Oh well.

For better or worse we tend to learn better from our own mistakes rather than from the experience of others...
 

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Sorry for my ignorance but does that truck have a 215 or a 180
 

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Discussion Starter #18 (Edited)
180 pump with 215 injectors (5x.010)
 

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And you guys were screwing him all up on the AFC adjustments!
Bad advice!:spank:

You don't slide the AFC housing back. That DOES limit rack travel, by however many MM's you slide the housing back.

You mod the AFC arm so it slides further FWD... why?
To increase rack travel. You slide the housing back, you remove rack travel.

Der...

And with the pre-boost.
Sorry mtncountrykid, you never got the pre-boost right not only because you ground the AFC foot (which can be remedied by backing the pre-boost out the same amount you ground the foot down) but because you never patiently (and methodically) went about finding the sweetspot.

It's 1/4 turn at a time.

If I were you, I would slide the damn AFC housing forward, switch to the light TST spring, the heavy one is for huge power setups.

Then re-read the last few pages of my "bogging/slow-spooling" thread and you'll find the hints on getting those pre-boost & starwheel settings dialed.
Your problem was the pre-boost. The starwheel won't affect spooling time.

And you're wondering about 1600º EGT's. What S300 do you have?
 
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