Engine/Transmission (1998.5 - 2002) EGT's seem too low

[cmills]

fuel pressure

I checked the fuel pressure and it was fine, so now what? With 29lbs of boost with just 275's I would think it would have to be getting enough fuel, right?

 

[darkhorse]

What puzzels me is why you have 29 lb boost. I think you may be over boosted & you are blowing some of the fire out so to speak.

 

[cmills]

What can I do, I messed around with that adjustable elbow and I couldn't get it to change?

 

[dcamilleri]

Hate to tell you this, but maybe you will thank me later: Drill your exhaust manifold for your pyrometer probe. I prefer to use the rear 3 cylinders just in front of the turbo. This will eliminate the variables that can come into play with the probe behind the turbo. Since the #6 hole has a tendency to run a little hot it is good practice to have it in the exhaust stream. I have burned holes through pistons with a probe after the turbo and never exceeding 1000 degrees. I have seen numerous diesels suffer from siezed pistons and scuffed cylinder walls and it is a shame if it happens because you guessed wrong as to how much tempature difference there really was. While the standard deviation is listed as about 300 degrees, it can vary by more than 500 degrees. I like to play it safe. Any time you exceed 1300 degrees for any length of time melt down could happen without warning and it isn't pretty. Better to err on the side of caution, after all that is why we have gauges. Last time I looked Banks had a good article on EGT's and why the probe needs to be in the manifold before the turbo due to the erratic tempature changes with the probe after the turbo.

 

[cmills]

EGT's

I know the best spot is in the manifold, but I guess I was just too paranoid about the probe busting off and going through the turbo, although I know that is very very unlikely, I'm going to try and srew the little allen screw on the elbow out a little more tomorrow as I don't think I turned it out as much as I could of. Just curious, what would happen if I took the screw all the way out? Would it still be able to build a fair amount of boost, as I was going to take it all the way out and see if the boost would go down quite a bit and see if the EGT's would go up some, but I don't want to if it will hurt anything or throw some codes.

 

[dcamilleri]

You still haven't said what your power level is like. Does it run like always? Is power down? If power is down some remove your MAP sensor and clean it. I wouldn't spend a lot of time trying to lower boost #'s unless you were over 35#'s. Your high boost #'s could be from a stuck waste gate. Install stock elbow and see if your boost drops back to about 22.

 

[darkhorse]

I was thinking the waste gate might be stuck too. BTW what turbo do you have & what's the size of the exhaust turbine housing?

 

[cmills]

boost

I have the stock turbo and housing, the power seems ok I don't really know what it should be like due to fact that I just had it rebuilt and it had bigger injectors and a box before. I don't have a stock elbow, all I have is the adjustable ones.

 

[dcamilleri]

I would suggest testing your wastegate. If you have access to compressed air and an adjustable pressure regulator. Attach regulated air supply to hose that goes to wastegate(where it leaves the elbow) gradually start increasing air pressure to the wastegate while watching the linkage on the actuator. At somewhere around 20-25#'s the actuator should move thus opening the port on the wastegate. If it doesnot move gradually increase air pressure to a max of about 30#. If it still doesn't move it is stuck and will need to be freed up to make it work propper or left alone knowing that it doesn't work. This isn't a big problem unless you add more fuel at a later time and then you could possibly overspin your turbo.

 

[cmills]

wastegate

Can I just move the linkage back and forth by hand and see if it is stuck very bad, If so how hard should it be to move?

 

[dcamilleri]

The actuator is very hard to move. Do you have access to compressed air? Even a portable tire inflator could be made to work.

 

[darkhorse]

It's a pretty stiff spring that holds the gate closed. Air pressure is the way to go. I used a bicycle tire pump with a pressure guage built in. I could clamp it right on the nipple on the actuator can. A factory waste gate should open around 20-22 psi.

 

[cmills]

wastegate

we have an air compressor, but I don't know how I would be able to tell how much pressure i was putting to it, so I'll just use a bicycle tire pump like Darkhorse said and see what happens, if it is stuck what should I do?

 

[dcamilleri]

What you are trying to achieve is to see if the actuator rod will move. If you take an air hose with a blow gun attached or some other fitting so you can adapt it to the rubber hose that leaves the elbow. Apply pressure and watch the rod on the actuator. It should move about 1 to 1. 5 inches(a guess) if it moves at all it is probably ok. If it doesn't move or only moves a small amount the wastegate could be seized. Usually when they seize it is due to carbon building up around the shaft. Repair would mean removal of turbo from engine and then remove the rear plate from turbo(it is bolted on) this will expose the wastegate(a small valve that opens to relieve exhaust pressure from the front of the turbine wheel. If you don't have a pressure regulator, you could turn off the power to your compressor and bleed off the tank pressure until you are at about 40psi then apply air to the line. Good luck.

 

[cmills]

wastegate

Thanks dcamilleri, I never thought of just letting the pressure down on the compressor, good idea, I'll try that and see what happens, it'll probably be after Christmas. Since I've had the elbow on there with the little allen screw in all the way does that mean that the wastegate hasn't been used at all since that elbow has been on there? If thats the case I could see how it might be seized due to the fact it hasn't moved for 150,000 miles.



thanks,

Cory

 

[juicedcummins]

Screwing in the allen screw raises boost. Turning it out lowers boost.