3406E warms up looses boost ?

[Bengy88]

Also does it have the correct turbo? I’ve seen people put s400 turbos on these engines and cause over boosting and eventually serious engine damage.

[tree98]

(12-11-2024 )Heavyhauler Wrote:  The boost is usually around 20/28 pounds.

I'm not a cat expert but I know this is too low

(12-11-2024 )Heavyhauler Wrote:  I always noticed that the fuel tanks would be so hot you couldn't touch them. once that happens she will be stuck in her funk.

Fuel isn't passing through the head and back to the tank as fast as it should be. Check for fuel line restrictions going into and out of the head.

(12-11-2024 )Heavyhauler Wrote:  Buy new stacks to lift the EGTs to start ?

This isn't going to solve anything.

[Rawze]

(12-11-2024 )Heavyhauler Wrote:  ...Buy new stacks to lift the EGTs to start ?

just generalizing here...

= = Turbocharged engines need as much free-flowing exhaust as possible, post turbo, to prevent fuel efficiency losses and trapped heat. Purposefully causing any exhaust restrictions, especially to try to slow down a turbo, is severely harmful to fuel efficiency and engine/turbo longevity. If the turbo is over-spooling, then it is either the wrong model for the engine,.. or its being adjusted improperly (via wastegate, vgt setting, bad ecm programming, etc).

= High fuel temps can play a role in fuel mileage losses, but not so much power loss unless its extreme. Also, many commercial diesel engines fiuel system are designed to warm the fuel, via return lines, passing thru cylinder head or other components before returning the fuel to the tank(s) to help prevent cold weather gelling, keeping the tanks warm. So, if the cylinder head is overheating (bad programming, overboosting, poor coolant flow, something wrong, etc.) then the return lines on the fuel system will get too hot too.

== fuel temps can get also excessive if the pump is having to over-work to make up for internal leaks .. such as leaky injectors, common rail leakage, fuel pressures are higher than they should be for whatever various reason, or there is some other excessive flow issues (too much flow bleeding back to the tanks, or back around to the input of the pump).

[Mal4shtf]

Record fuel pressures under load with a manual gauge. Should be at least 95psi but 100 or more is desired. There is a fuel return check valve in the fuel filter head on the engine. It is the only thing regulating fuel pressure in the system. It's a spring type. Spring gets weak as it heat soaks and collapses easier. They are lik 100$ it goes in the filter head upside down near by where the fuel return hose comes in from the back of the head. More than likely your problem. Woron alot of e model cats. Pm me if u need help.

[Heavyhauler]

i've done some consulting with my friend ( literally neighbor ) that owns the truck. we haul together 5 days a week and wrench on each others trucks. i've invited him to this forum to run along this super helpful wheel of knowledge. There is a list of good valid questions to be confirmed on our end and helpful info to top it off.

$tree98 = What do you think is a healthy boost range for a cat? I run the ISX so I wouldn't know particularly.

Rawze = I agree with the generalized list, we will work through the check list and report back. I will also agree about the possible programing that could exist is a loose end to be answered. It might be tuned at 550 but I can't officially confirm, tho I'll talk to the driver/owner in the am and see. Hopefully he will be joined asap

Bengy88 = There are no resisters in line of any kind that I'm aware of. Tho we talked about that as an option but we never went down that rabbit hole of fooling the ECM

[Bengy88]

35-36 psi boost on a 3406e is healthy. It’s not unheard of to see up to 40 on them with the higher horsepower engines but anything over 40 and I would be figuring out what’s wrong. Anything below 35 and I would also be figuring out what’s wrong. Could be anything from a boost leak, worn turbo, bad wastegate (I’ve seen a ton of them rust out), or as mal4shtf said your fuel check valve. If your engine can’t perform properly then it’s not gonna spool your turbo properly.

[Rockyhill]

So I’m the owner of the truck in question so far I’ve changed the intercooler, all fuel lines are brand new turbo is good, I’ve ran it with the waste gate plugged off the air and fuel sensors on the motor have been changed the three little check/relief valves in the filter housing has been changed new fuel pump I have a fuel pressure gauge plumbed into the cab it runs around 95 psi when driving down the road had the rack ran recently at caterpillar always service the truck at around 250 hrs the truck will spool quick and run about 25/27 psi for boost in the morning but as the day goes on it becomes slow at building boost and will only build about 15/18 psi of boost it seems to be worst on warmer days I have another mechanic thinking one of my injectors might be bad as it gets hot we’ve had it on a laptop all the fuel pressure runs at desired when running down the road also it only acts up after going down the highway after about 20 or so miles and when I stop to get loaded again it will be ok till I’m on the high way for a bit

[Mal4shtf]

Ecm circuit boards see alot of heating and cooling cycles. Typically an ecm fails on the injector driver side which is where all the high power and heat is generated. Solders get weak after so many cycles. It can cause this and I'd be leaning that way if you've done all the other listed approaches which you have. I'd bet that ecm gets warm after a few miles of load and doesn't drive the injectors enough. I'd caution driving it like that because a bad ecm can cause improper fueling and tulip the valves eventually resulting in a dropped valve. Catastrophic. There are a few companies that can bench test the injector driver as well as the regular circuitry of that ecm and you can find them on Google. The one I use (can't remember name) has locations in Texas and Florida. Make sure whoever you send it to can bench test the injector driver. You may change injectors anyway.

[Rockyhill]

Mal4shtf honestly I’ve been leaning towards the ecm the only thing that throws me of is that it doesn’t throw any codes is it possible for that to happen also the engine is a 1lw fuel flows the the ecm for cooling and I have to add every once in a while when I’m coming from a dead stop and start going through the gears the rpm will be coming up truck will be building boost and all of a sudden it will almost act like a dead pedal I lose all pulling power I’ll grab another gear then it will go back to normal. I had the truck on the lab top while it has acted up and if I have the pedal to the floor it will read it at 100% throttle so I believe I can rule out the pedal