I have a 2004 ISX w/EGR 500. Motor was just rebuilt 1 month ago after 750,000 miles. Everything was replaced except the cams which were checked and the fuel injectors new 6 months prior. Since the rebuild the truck pulls ok. Actually it has very poor bottom end even unloaded, but the turbo boost fluctuates on full throttle full load between 25-41psi. Then after a minute or so of cycling like that, it stabilizes till the next shift where it starts to fluctuate and cycle again. So I am never achieving full power. In addition when the Jake is active the truck shakes violently. I think I have a fuel issue here and called Cummins. They don’t know what it is. We hook the insite up to it and there are Zero codes.##


Any experts out there??


Thank you



Tom

Sorry, not an expert, but...
Causes in order of frequency:

1)Turbo Vane Control Valve. Can't be tested, but can be swapped with a known functioning unit from another unit, or replaced for (alot, but under $1K).

2) Exhaust Pressure Sensor (manifold drive pressure). Same as above, but much cheaper to replace!!

3) EGR Cooler Flange Leak: Pressurize entire system and hit it with spray soapy water. Check for bubbles at flange and base, etc...

Hope that helps and good luck Tom!!

the vain controller on the turbo? both that and the supply unit on the head are brand new.

where is the EPS located??

how do u pressurize the EGR system while its not running?

we have 10 of these trucks and tons of extra new parts on the shelf. i will throw parts at it. LOL

The vain controller is the Turbo Actuator. It is the unit that sits on the turbo that has the collant lines running to it and the electrical lines running to it. If this were the case it would be throwing you a code.

The EPS would be on the intake manifold about half way down the horn of the intake.

If you use a simple coolant system pressure tester, the problem is that the egr cooler will see high pressures then what you would be safely putting on the hoses. Normal testing pressure is 16 psi at the surge tank. The egr cooler will see higher pressures than that when the engine is idling.

I personally would check to see if you have a boost leak. A small boost leak at a boot will not show up under normal driving, but at full throttle full load applications it will do exactly what you are describing. Soapy water and a spray bottle will help you check this. Have someone run the engine up to 1800 rpm while you spray all connection points. This will save you some money if it is a boost leak. If it is not a boost leak then you can proceed to throw money at it. I just would check all basics first.

The actuator and the vane controller have been replaced once. No change.

The turbo was replaced with no change, thus the hoses were unbolted and re-bolted so the chances of a leak at the turbo is unlikely. We will check the hoses on the intake side and change the EPS tomorrow as we are swapping out a set of injectors from another ISX motor as a diagnostic aid.

The actuator on a 2004 does not have coolant lines or any electrical running to it. And the Exhaust Pressure sensor is located on the T-Stat housing. The turbo actuator and actuator controller can be tested....with or without Insite.

You do not have a fuel issue. When you said you replaced the actuator and the controller, you are talking about the controller under the air compressor right? If not, check that box for leaks while engine running. If so, right next to that box you'll see the ground stud for the engine block ground. There is one wire coming from the engine harness - so it will be red - that absolutely needs to be connected.

An EGR Cooler will not cause this problem without other symptoms. The injectors are most likely not the cause. If you do have access to Insite, be sure EGR temp sensor, Intake boost sensor, and Turbo Intake temp sensor are all reading correctly.

The actuator controller we replaced is located on the block up top of the head right by the A/C compressor.

we will inspect the other areas u mentioned we will inspect today.

The engine has one more symtom but i feel is unrelated. The EGR Valve hiccups under partial load. so we are replacing that as well today.

Update 4-15-09

Ok well we found a small leak in one of the hoses on the turbo pressure side and fixed that. It was in one of the flexible hoses.

The truck is running way smoother now with the injectors. BUT...

Now the truck is hiccuping way worse then before via the EGR and the boost is WAY high and i am not exagerating. I saw it go up to 55psi this morning. 55!! In addition now the EGT is WAY low. like 500-600 degrees at full throttle on a pull. Should be in the 8-900 range. Even the air cleaner guage is way high. in the 10-15 inch H20. This is crazy. I am headed back to the shop.

I don't know much about Cummin's or EGR but the only way I can get 55psi boost is to add more fuel.......Injector problem???

__________________

THERE IS NO SUBSTITUTE FOR CUBIC INCHES

Update #2 4-15-09

Problem solved!!!

Turbo actuator controller on the head by Thermostat housing. We put a new one on it last week. Must have been bad from the start. Everything is working to spec. I feel like i have 500 HP now and everything is working perfect. So far... no whammies lol

Awesome to feel this motor again. But that 600+ CAT would be way better :P

Thanks for all the help guys!