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Derek Neustaeter
Derek Neustaeter,
Category: Medium and Heavy Trucks
Satisfied Customers: 4
Experience:  Heavy Equipment Technician at Warner Industries
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Spanky, I am a 35 year truck mechanic. I have a 2004

Customer Question

Hi Spanky,
I am a 35 year truck mechanic.
I have a 2004 Navistar with DT466 E.
The truck was running rough with injector codes. I ran all the tests with my Snap On Scanner (2) years old and updated.
They all passed. I then ran all the ohms tests on the injectors as manual states.
All but 2 of the injectors passed. Customer decided to replace all 6 and the harness/valve cover gasket.
The unit runs great, except-when you shut it off and restart, it has no acceleration off idle and seems to be in a de-rate state. The load percentage at idle when this happens is 63%. What could be loading down the engine so hard at idle?
When the truck is running good the number is *****%. All fuel and oil and temp are within specs.
Thank you
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Derek Neustaeter replied 1 year ago.

Hello there! I am a qualified Heavy Equipment Technician here at Just Answer, I will help you diagnose and repair the problem you are having with your DT466E engine.

I have had similar issues to the one you describe on the DT466E engines and there can be a few solutions to the problem. The first thing I would check is the ICP (ignition control pressure) or the oil pressure that pressurizes the fuel in the injectors. This pressure is vital to the proper operation of this engine. Monitor the ICP with your scan tool both at idle and under load and let me know what the pressures are at. Even the smallest leak in this high pressure oil system can cause a no start, hard start, improper idle, or low power issues.

The other common issue with this engine is the fuel lift pump. Fuel pressure can be checked using a T adapter on the output line of the fuel pump. Fuel pressure should be greater then 7psi.

Check these things and let me know what you find!

PS- I wouldn't let the engine load number worry you. I have noticed this number being abnormally high as well even under normal operating conditions. I'm not sure what inputs international uses to calculate the engine load, but it is not very accurate!

Customer: replied 1 year ago.
Ok Derek,
I will get this information back to you tomorrow as I am on the road at the moment. You did mean injection not ignition correct? I also forgot to state that the tps is functioning normal, even when engine wont rev up. Thank You
Expert:  Derek Neustaeter replied 1 year ago.

Yes, I did mean the injection, thank you for correcting that.

Have you ever encountered any communication errors with the truck. Another common problem with these trucks are the power to the ecm. Have you have had the truck no start? Surprisingly enough, even the slightest bit of corrosion on the battery posts can cause some really, really strange problems.

Customer: replied 1 year ago.
Hi Derek,
It communicates fine every time with my scanner. I also ran the Koeo & Koer tests and
it passes both no problem WHEN it is running good. When it isn't running good it wont perform either test.
Customer: replied 1 year ago.
We have been through the batteries, weather connectors, cables and all ecu connectors multiple times.
We even tried new batteries to no avail.
Expert:  Derek Neustaeter replied 1 year ago.

The scanner will communicate fine with the ECM with an intermittent voltage drop, but can still cause engine issues. Just something easy to check. I have diagnosed these engines for hours, only to clean the battery posts/cables and have the problem disappear. Sounds odd, but trust me on this one!

Let me know the ICP running pressures when you have a chance.


Customer: replied 1 year ago.
Ok Derek,
Thank You
Customer: replied 1 year ago.
Good Morning,
The ICP pressure at idle is 680-701. At 2400 Rpm it is 2083.
The fuel pressure at the pump is 55 psi.
When the truck is running bad, the ICP is 678.17
Please advise from here.
Thank You
Expert:  Derek Neustaeter replied 1 year ago.

Good Morning,

According to the readings you provided, your problem definitely lies in your High Pressure Oil system. In order to repair the problem. Complete the following steps:

- Disconnect the IPR valve's electrical connector and start the truck. If the engine's ICP pressure stays constant, your problem lies in the electrical from the harness to the IPR valve, or the IPR valve itself.

- If the ICP pressure does not stay constant, you have a high pressure oil leak that will need repaired. In order to find the leak , disconnect the high pressure oil line that runs from the pump to the left side of the cylinder head. You will need to attatch an air chuck connector to this line to fill the cylinder head oil galleries with air. Apply the shop air and listen for leaks. Using a stethoscope can be benificial to locating the leak. Once the leak has been located, dissassemble and repair the oil leak!

I am happy I could help you out this morning, and if you have any other questions, I will more then happy to help. If you could leave a rating on how my service was today, that would be very much appreciated.

Thanks so much,

Customer: replied 1 year ago.
We are testing now Derek. I will get back to you with the results.
Expert:  Derek Neustaeter replied 1 year ago.

Sounds good, let me know what you find!

Customer: replied 1 year ago.
Hi Derek,
The truck will not start and run with the ipr unplugged. When cranking, the icp reads 368 psi.
With the ipr plugged in and the icp disconnected the reading is 722. what is getting me on this is the truck runs great at random. When it acts up it wont respond at all and the rps are at 400 and charging drops to 12.5 volts. There is no warning on this. One minute runs fantastic and you shut it off and restart it and it is horrible. Reshut it off and let it sit for 20 mins and re-starts and runs great and charges & idles great. There is no check engine light and only code is SID 247 FMI 2 Flash code 222 brake circuit fault and it is inactive. If I clear this code-it keeps coming back but is inactive every time. The brake lights work fine.
This one has me stumped.
Thanks for your patience on this.
Expert:  Derek Neustaeter replied 1 year ago.

As a technician, you need to not get side tracked and focus at one problem at a time. The problem you are having is a high pressure oil issue. It is in no way related to your brakes, or your charging system. Complete the steps I provided above and they will lead you to the solution of your issue.

Customer: replied 1 year ago.
Hi Derek,
I don't know if we are still active or not.
I got the hpop readings hot and cold.
cold temp is 2172-2460 when at 2400 rpms
cold idle is 690 psi.
Hot engine idle is 613-710
Hot engine at 2400 is 1200-1800 psi.
I think you were correct and the hpop may be bad.
Your thoughts?
Thank You
Expert:  Derek Neustaeter replied 1 year ago.

I agree, you definitely have a HPO leak! Please diagnose as I described above and your problem will be repaired, guaranteed! Please leave me a positive feedback rating for diagnosing your problem.

Customer: replied 1 year ago.
Hi Derek,
When we run direct air into head we definitely heard air leaks. we did replace all the fuel rail seals when we replaced the injectors. we pulled the oil/fuel rail back off to inspect. all look ok.
We then block off all the ports in the rail and pressurized the rail- all ok no leaks.
We then applied air pressure to the oil ports on the new injectors and found air leaking out of the 2 slots on either side of the hole for oil rail. The company I bought these from says some leakage is normal as long as its not excessive. How much is too much-I don't know. But how can I run a pressure test with automatic leakage?. I'm waiting to hear back from them.
We are now going to run a dead head test while cranking at the Hpop. Do you know what that pressure should be?
Thanks Again
Expert:  Derek Neustaeter replied 1 year ago.

This really depends on the manufacturer, can't help you much there as I don't have access to whichever manufacturer supplied them.

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