apache

Great information here from all of you, anyone wanna breakdown the injector pump on say a first gen. It seems easy to up the HP by tuning the pump, but I dont understand how the 4 different adjustments play in. Say the full power screw, is that top end only well say? adding fuel at full throttle and boost?. I just see more fuel as more power and smoke if the fuel is burned, but I know its not that simple. How can you not over lean a diesel. Gassers run best at a 14.9% constant ratio of air/fuel. But it dosent matter in a diesel? My brain is going into overload thinking about this. better stop here
Will turning up the pump at any level within reason cause a shorter life for the pump from higher internal pressures??

David Oxland

Re your question 3:
It is most likely that the site you saw stating that "compressed air is blown in with the fuel" is referring to a very old form of injection called Blast Injection. Not used any more as far as I know. It was dreadfully inefficent and labour intensive. Old timers will know about this.

question 9: More power does not necessarily mean more smoke. Diesels run mainly clear as long as there is enough air to burn the fuel. They run in an almostly exclusively excess air condition; when more power is required more fuel is added and at the point where there is insufficient air to combust that fuel, smoke begins to appear (as carbon particles).

Hope this helps

98 2500

The edge ez and comp's are called fueling boxes. Which one is for milder app's, the EZ. How are they different than the ones like i saw on Trucks, where there was a little display and you could change power levels on the fly, forget maker of the product. Why do the boost gauges show no vacuum, its almost as if they don't have a vacuum in the intake. MY brakes seem to be proof of this. Also when i get a boost gauge should i get a 30 or 60 psi. Well, i will wait for the answer about the box because the one they showed on TV also had EGT and boost incorporated into the display. and the website showing the air injected with fuel http://auto.howstuffworks.com/diesel1.htm

BTW, i really appreciate the help here, i feel at home already

drafalske

A diesel also does not produce vacuum. Like I said, the intake is completely. With no restriction such as a throttle body or carburetor, it is impossible to create vacuum. Thats why your power brake booster is driven by the power steering pump. How that works is still a mystery to me though.

Lil Dog

Well Apache the first gen pump has its checks and balances to give you fuel at different RPM bands.

The full load screw you mentioned really just ups the fuel pressure setting in the pump so the fuel rail pressure per injection pulse is at higher pressure, more fuel for the same injection event. Problem is that the increase on that component is about 75% in the lower RPM band and doesn't give alot of increase in the upper RPM area. That is evident with the huge amounts of smoke and the elevated idle speed.

The second factor is the AFC spring and AFC cone adjustment. This tailors the fuel vs boost and allows you to let the turbo catch up, for lack of a better term, to the fuel administered before a higher rate of fuel is allowed. More spring tension, higher boost required for advanced fueling from the pin. The aneroid or smoke screw advances the AFC cone for low boost levels. So before the boost is created the fueling is advanced.

Thirdly is the governor. This allows the fueling at the higher RPM band. With all the other adjustments you work in the range of the governor, however the governor is only set to a certain speed by the factor of spring tension. If you can increase the tension, you can get more fuel up in the near red line area of the fueling curve.

I messed with my 89 and 93 for years and learned this all by feel and testing. Also by learning from the great group of guys here and on other sites.

With reguard to not over leaning the diesel, well you have to look at the combustion to get a feel for that. Basically with a diesel engine you are adding the fuel to the compressed air to create the pressure in the cylinder for power. Not having to worry about the combustion charactoristics of the fuel to ignite like in gasoline.


J-eh

MCummings

Diesel Fuel is very heavy, and is hard to pump, plus, the VP44 requires Alot of fuel, at low pressure.

We need 90-150GPH, at 15PSI.

Cam Upgrades are a good benefit for better drivability, and CAN make more power, but you have to be pushing the limits allready.

The Stock Cam Is Adequate, and there is really only 3-4 reasons to change the cam out.

Faster Turbo Spool-up
Better MPG
Less Smoke
Lower EGT



As the turbo spools up,, making more boost,,, that is the air going into the cylinders. Then,, just like a sprak plug would zap the A/F mixture,, what happens in a diesel is the injection pump pumps fuel through the injector, and the air is so hot, the fuel immediatly ignites, and that's where the powerstroke comes from, it is then exhaust like a standard 4-cycle motor.




On the 24V, it is mechanical/electronic. You cannot adjust it, but it has a finite adjustment of timing. I think it starts with low timing, idles with high timing, and WOT with low timing again. (It's all emissions related crap)

The P-7100 pump (12V's, from '94-'98.4) are mechanical, and have fixed timing. You change thte timing by pulling the pump gear off, and "backing up the motor" then tighten the pump gear back down.



It's been covered,, we have air heaters in the intake plenum (the part your dipstick attaches too), and the look like a fancy toaster overn, and get red hot when it's below a certain temperature that the ECM is programmed for. (Something like 60*)

When your Wait to Start light is on,, the grid heaters are warming up,, and pull a considerable amount of power. Something in the neighborhood of 2,600Watts. (Ever notice your headlights dimming after startup?)




You have an HX-35 with a 12Cm Housing Wastegated at ~20PSI.

There is no blow off valve, and boost is directly related to the amount of heat energy in the exhaust manifold.

The Holsets are Dual or Twin "scroll" turbos, whereas, they have two openings in the exhaust side, one side goes to drive the turbine blade, and the other to the WasteGate port.

At idle, and boost below 20PSI, the WasteGate is securely shut by a spring inside the wastegate actuator.,, once boost starts to approach 20PSI, there is a boost line running from the compressor side of the turbo to the wastegate actuator, and when the boost overcomes the spring inside the diagphram/actuator, it moves an arm, which inturn moves the wastegate "flapper" out of the way,, allowing extra energy to be bled off and put down trhe downpipe, instead of spinning the turbine wheel faster.

Not all turbo's have wastegates, but the purpose, and benefit of the Wastegate is to allow you to run a small exhaust wheel housing,, which makes the turbo spool quickly, and to keep you from overspeeding the turbo.
You Wastegate off the extra energy.
If you mathced the turbo to have full boost at full power,, it would spool slower than a Wastegated turbo, making your truck even slower than it is now, OR, it would spool up fast, and then make too much boost at full power, and grenade itself from to much RPM.




You have a VP44 injection pump, that is electronicly controlled by the ECM, and it's own Computer. The computer's control a solenoid, that controls how long fuel is injected into each cylinder.

A COMP or EZ, just hold this solenoid open longer, and it makes more power from more fuel. You can only hold th solenoid open for so long before you exceed it's "Duty Rating" and melt the solenoid,, either open, or close,, either way, the pump is trash. (They are just now becoming rebuildable,, and that is an option you might want to seek)



Because,, Like said,, It's Better Off Modified Baby



Because Fuel is cheaper than air.

It costs $1,000 to have 150-180 more HP worth of fuel, but it will cost you $3,000 in turbo upgrades to be able to support the fuel.
Cheapest thing to do, is put a bunch of fuel to it,, get 180 more HP, and live with the smoke and EGT.



Can't help you there,, but some good linnks have been provided.



It wil become obvious when something is not correct. Right now, although Loud, the motor runs smooth, and purrs. When sommething goes wrong, it will miss, knock, sputter, and smoke. Just a small bearing malfunction will make a bunch of racket.
Have fun.

Merrick

98 2500

Being as there is no distributor, what is the timing measured from, a crank position sensor? can someone explain the different fueling boxes, stacking them, etc....

apache

Thanks for the breakdown Lil Dog, some how it made me want to ask more questions. I want to gain a little on the 93 dually 4x4 I picked up and have read all I can find on the pump tuning. The dually seems to acomplish more with less pedal until your pulling a hill. My 2wd had the pump rebuilt and a said gain of 15% HP. It seems to need more pedal for flat ground but will get with it when floored. The dually just slowly gains speed. i go up a grade every day thats ill guess 6% or more. The 2wd will pull it 80+ mph in OD, the dually will just keep 62 mph and thats it. No smoke, runs smooth and quiet compared to the 2wd. The dually is untouched pump wise. I get 16 mpg in the dually and 20+ in the 2wd cant complain there. I dont want to push it to much with the dually, it will haul the camper and tow mostly and its an 518 auto. Any advise to offer.
Thanks a bunch!!!!

Lil Dog

Apache,

I will PM you with my email address so we can jaw this out.

First hand from what you describe (quiet, lower power, no smoke) it sounds like the timing may be off on the dually. I am thinking retarded a few degrees. If you can get the timing checked that may help to at least get some of the pop back. Then tweaking the pump can be done without going mental with temps.

J-eh

dakar

98 2500 Just a word of thanks for starting such an enlightening thread, after 20ish years of playing with gassers from tear down to hopping them up i was fairly clueless as this is my first diesel as well, and curtousy of everyone else posting answers I've gained quite a bit of understanding of just how a lot of this critter works, and more importantly WHY they work and what happens when they don't.

My thanks to all who've contributed!

dgm1958

[QUOTE]Originally posted by drafalske
A diesel also does not produce vacuum. Like I said, the intake is completely. With no restriction such as a throttle body or carburetor, it is impossible to create vacuum. Thats why your power brake booster is driven by the power steering pump. How that works is still a mystery to me though. If a diesel does not produce vacuum then how does a naturally aspirated diesel get it's air? I have a tractor with a 354ci in line 6 perkins diesel rated at 92hp that is naturally aspirated and it has lots of vaccum!

cp

The naturally aspirated diesel fills its cylinders with 14.7 psi (or whatever atmospheric pressure happens to be) air from the intake manifold.

True, there is a slight difference in pressure from the cylinder to the air filter, but nothing like the vacuum created by pistons pulling against a throttle plate.

dgm1958

If you put your hand over the intake that goes to the air filter it will almost put ahichy on your hand. Thats got to be alot more than 14.7psi

wannadiesel

Yes, but without the restriction of your hand there is no vacuum. Manifold pressure is the same as atmospheric pressure (or dang close) without your hand blocking the intake. When you put your hand over the intake, then you have vacuum because you have restricted the airflow, causing the pressure in the manifold to drop below atmospheric.

98 2500

good explanation of the lack of vacuum guys....can you use a blow off valve with these?