Installed DDP1 50hp injectors in a 180hp 1996 4x 2500 with Banks Power Kit, HTT exhaust, ATS transmission, GV overdrive. I can controll smoke and pass the snap throttle test but it smokes excessively with full throttle accelleration. I have moved the Fuel stop plate (Banks Ottomind) .030 forward of the OEM position to contain full throttle smoke with no apparent effect.

I have tried all the TST springs to no avail and am back to the OEM spring which seems to work best for my condition

Got any ideas on how to contain the full throttle smoke?

 

Have you ever touched your smoke screw?

 

hummm, the TST AFC springs are supposed to do a decent job in controlling smoke.

 

more air

 

I have been working with the AFC trying to control smoke. Using a Bicycle strut pump/gage hose and fittings I tested the AFC to determine how the different springs effect the AFC operation. I purchased the TST springs to see if there were any effective smoke control measures which would address my problems. I also tested the springs to determine what their spring constants were for comparison purposes. I found the following.

TST Light(K=39lb/in, L=1.48"), Medium(K=68lb/in,L=1.48") and the OEM(K=72lb/in, L=1.16") springs. The spring constants(K) for the Medium and OEM springs are roughly the same. The difference is in the spring length(L). The longer TST springs provide for a greater spring preload to offset the intake manifold pressure where AFC fueling starts. This contributes to turbo lag as the turbo has to overcome the preload tension of the AFC spring so it can start increasing fueling. There is a bootstrapping action with fueling providing greater exhaust pressure/heat energy to get the turbo going to feed more pressure into the intake manifold.

The AFC movement vis manifold pressue deflection curve shows that the star wheel spring tension adjuster just moves the spring curve up and down the pressure axis. This is a pretty rough way to achieve smoke control during fueling and maybe adequate for static fueling. Unfortunately engine loads cause fueling to lead the engine capacity to burn the fuel leading to lots of smoke during accelleration. With a rapid increase in turbo speed and manifold pressure during accelleration the AFC moves the fuel injection pump to the fuel stop plate limit at about 15psi of manifold pressure for the OEM spring. Then running under a static load manifold pressure drops back so the fueling then is determined by the AFC control spring as it balances fueling against load. So it appears that smoke control for accelleration under load has to be done using the fuel stop plate.

Unfortunately tailoring a stop plate is beyond my capacity.

If some one out there has gone through this process and has come up with a fuel stop plate which would address my problems I would sure appreciate an input. I could use a good P7100 pump man if there is one here is southern California.

I am looking for good low end HP/torque and maximum fuel efficiency. I have a 10K 5th wheel which I pull with this rig and we also use this truck for our long trips out of town.

 

Unfotunately this is a bit beyond my knowledge so I dont know what to tell you. Im not real sure pump mods will bring the results you are after. Going with a bigger/badder turbo (as whitmore said) should clean the smoke up nicely.

Can you pass a smog test right now?

What are you running for a plate?

 

I dunno which plate will do ya best but they certainly arent hard to tune up.................I build a 100 plate for my sons 94

some where here is some plates to gander at .........I will see if I can find em

 

here is some plate info

https://www.dieselbombers.com/12-val...-profiles.html

 

I think the smoke screw you are referring to is the stud screw on the back end of the AFC housing. I checked the set point of this screw and it was set at the limit of the AFC diaphram movement back. This should be the most lean setting. This is also the fueling at the idle point of the engine. If I were getting allot of smoke during the throttle snap test this would be a good adjustment to use. However, I don't have any problem with the throttle snap test just accellerating under load.

Thanks for your input.

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The AFC OEM .030" orifice, which delays onset of fueling, should allow the turbo to spool up before onset of excess fueling with accelleration. When I had my timing set the well meaning pump man drilled out the orifice fitting to 1/8" effectively removing the orifice. I subsequently machined an "O" ringed orifice to replace the .030" orifice and that didn't help. I also tried a .040" and .025" orifice thinking one of these would help. Neither did. It seems that you can't get more air without more fuel and if you get more fuel you get more smoke. I suppose that the other approach would be with a turbo with the ability to build manifold pressure faster than the the PDR HX-35/14cm I now have. I still have a 12cm housing which might help but then I would be having problems with exhaust temperatures during towing. Unfortunately selecting a turbo is somewhat like going forward blind folded because there is little data on on most of the turbos being published. Most turbo/housings run to $1,000 to $2000 so cut and try would break the pocket book.

Thanks for your input

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If the only road smog test is the Throttle Snap Test which is the diesel smoke opacity test of 40% opacity I shouldn't have any problem. This no load test includes the following:

The engine is held at full throttle for approximately two seconds, the released. This is done 5-6 times, with the first 2-3 times being considered invalid, as built up carbon being blown out of the exhaust may show darker smoke. The initial burst of smoke from the next several accellerations is simultaneously compared with a tinted plastic sample while viewed against a white background under daylight conditions.

However, I understand from postings that the highway patrol also is monitoring smoke produced under highway driving conditions. This may be a problem for all who generate smoke during accelleration and that is my concern.

I am running a Banks Ottomind fuel plate which came with my Banks Power kit.

Thanks for your questions.

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That is an excellent posting of fuel plates. However, there is a problem of matching the right fuel plate to an engine load profile. Do you have information on what fuel plate would work best for pulling a 10k 5th wheel? Steady load and accelleration loads. Using a 3.54 dif, ATS transmission and converter, Banks Power kit equiped engine with HTT exhaust manifold and ATF air intake.

Thanks for the great fuel plate site.

 

I dont know how you guys live with all the laws and rules in California.

I hope you can get it figured out. All I can suggest is a more appropriately sized turbo for yours fuelling mods. Good luck - I hope you can get it figured out - most guys want more smoke and you want less...