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2007 Caterpillar C-15 Acert NXS engine. 550 hp 1850 tq. I…

2007 Caterpillar C-15 Acert NXS...
2007 Caterpillar C-15 Acert NXS engine. 550 hp 1850 tq. I recently installed boost gauge to monitor boost. Boost never went over 30-33 under load. I was told this was fine, no problems.
Then I was off work for 10 days. Went back to work and my boost increased. I was getting 45 psi under heavy load, 1.5 mpg better fuel mileage, and under heavy load and during take off she was blowing black smoke. She was stronger and ran better than I've ever seen her run in the 5 years I've owned her.
This lasted for 4 days, then as I was climbing a mountain with 40k in the box, all of a sudden it was like somebody slapped her and told her to sit down, my boost dropped to 25 psi max under any condition, she has a lot less power, and my fuel mileage dropped to less than I was getting before the boost increase.
My question is...Was the increased boost an indication of an issue such as stuck wastegate? Or should I look into possibly having a boost leak now? Which situation was the best boost numbers for this engine?
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Answered in 21 minutes by:
9/15/2019
Technician: Cat Man, Cat Engine Expert replied 3 years ago
Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 10,344
Experience: I am ASE Master Truck Certified.
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Thanks for asking your question. I will try and help you out.
Does the yellow check engine light come on when this happens?
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Customer reply replied 3 years ago
It is on, but it is not for a boost code. The code is 385-1. The code did not change before the boost increase, during, or after.It has been throwing this same code ever since I had an injector changed and overhead done. I have replaced the sensor, but the code remains, so I'm not sure what is causing the code.
Technician: Cat Man, Cat Engine Expert replied 3 years ago
Thanks for the information.
A 385-1 can cause your intermittent low power. When this code is active the engine will derate in power.
This code is caused by either an oil leak at an Iva housing, a faulty Iva housing. Or a leaking Iva control valve.Please reply back if you need more help. I am happy to assist.
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Customer reply replied 3 years ago
OK, but the code has been consistent since the first of August. The boost pressure change only last 4 days last week. I get that the code can cause derating, but it was on the entire time and then just suddenly boost pressure dropped. What would have caused the sudden increase in boost and then the sudden decrease?Ok when the code 385-1 originally came on, I also had a code for the number 6 IVA. That turned out to be a wiring issue. I fixed that and no more IVA codes. I also replaced the IVA oil pressure sensor. When I replaced the sensor 2 years ago, it was a simple pull out the old one and install the new one. This time when I pulled out the old one, oil was coming out of the hole like it still had pressure even though the engine wasn't running. What would cause increased oil pressure at the sensor, even when it isn't running?
Technician: Cat Man, Cat Engine Expert replied 3 years ago
The Iva’s do not work all the time. They only work under load and under 1500 rpms.
If the 385-1 is not the issues. I would suspect either a stick wastegate or low fuel pressure issue.Please reply back if you need more help. I am happy to assist.
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Customer reply replied 3 years ago
Would Cat part #228-4800 (not sure what it's called), cause the 385-1 code?Also, will it cause damage to the engine running 45 psi boost?
Technician: Cat Man, Cat Engine Expert replied 3 years ago
Sorry. Not sure about that part number.
No. It will not cause damage to run 45 psi.
Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
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Customer reply replied 3 years ago
ok I've replaced the intake oil pressure sensor and the control solenoid. I still have the 385-1 code, although it's more intermittent now. Check engine light may stay off for 2 or 3 days or stay on for 2 or 3 days. Everytime I check code it says inactive even though check engine light is on. Now, today out of blue I got 2 new codes that show as inactive, 287-6 and 288-6, #3 and #4 IVA voltage high.
I had zero problems with the IVAs or oil pressure until the day they did the overhead. Now it's non stop for 2 months now. First it was #5 IVA randomly unplugged the day after the overhead, then the next day the plug for #6 disintegrated, the 385-1 code has been non stop the entire time, now it's #3 & #4 high voltage. Is there anything that would be a commonality amongst these issues? I prefer to think better of people, however the overhead was a freebee due to a $1500 misdiagnosis by the same shop a month prior
Technician: Cat Man, Cat Engine Expert replied 3 years ago
If the sensor and valve have been replaced. I must suspect a leak on one of the Iva’s.
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Customer reply replied 3 years ago
must have happened when they changed injector
Technician: Cat Man, Cat Engine Expert replied 3 years ago
That will cause it.
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Customer reply replied 3 years ago
after visual inspection, I can find nothing apparently wrong with IVAs or wiring. what would most likely be the cause of #3 & #4 throwing high voltage code at same instant?oh and the broken piece is for #1 & #2
Technician: Cat Man, Cat Engine Expert replied 3 years ago
Those codes are caused by faulty solenoids or a harness. Since you have codes for 3 and 4. I would suspect the harness.
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Customer reply replied 3 years ago
ok thank you
Technician: Cat Man, Cat Engine Expert replied 3 years ago
You are very welcome. I am happy I could help.
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Customer reply replied 3 years ago
I replaced the broken oil quill, replaced all o rings in all 3 oil quills, replaced intake oil pressure sensor, replaced control solenoid, replaced both injector/IVA wiring harness inside rocker box, and switched #3 IVA with #2 IVA. Still getting codes 385-1, 287-6, and 288-6.... no change. Where should I look next?
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