hino 165, 2008 CEL with P0087

[Yurik]

Hello,
2008 Hino 165 4 cyl
117,000 miles plus idle 4-6 hours per day 1100rpm
Getting P0087 code only on the highway driving at 55 and more uphill

Air and Fuel filters changed (replaced 5 times in last 2 month) DEF dropped and washed and reinstalled. Less then 0.5 psi drop
Dealer blamed injectors. Got new injectors installed. Still the same issue CEL, P0087 on the highway up hill.
Dealer seems no help at all. Planning a filing a complain with reginal rep.
I stripped the threads on air prime bolt on the filter housing last year and put some teflon tape on threads. Can this cause all this trouble?
I took supply bungee bolt from the supply pump to check for blocked screen. Found no screen there.

 

[greasytshirt]

Any restriction in the fuel supply will cause this code. If you had access to dealer software, you could look at historic fuel temperature, and temperatures above 200f suggest the pump has high internal leakage. I would be more quick to blame the pump rather than the injectors. But first the entire fuel supply system needs to be examined for restrictions. This may involve running the truck off of an auxiliary tank connected directly to the injection pump to rule everything out.
Air leaks in the fuel system can also cause this code, but hard starting/ prolonged cranking often accompanies an air leak.

You are going to destroy the DPF with those idle times. The DPF will get loaded with an abnormal amount of soot which will burn super hot during a regen. Is the tailpipe loaded with soot? If so, it's already damaged.

 

[Yurik]

Thanks GTS!
Truck has PTO that I have to use 4-6 hours per day. (Its like driving 35mph load) Its service truck.
Does DPF has anything to do with this code?

What do you mean tail pipe loaded, there is light coat of soot. Nothing abnormal

I have no hard starts, or prolonged cranking. It idles perfect and runs PTO with load at 1200 rpm no problems at all. it's only happens when I'm driving on the highway.

 

[greasytshirt]

The dpf has nothing to do with the code.

If your finger turns black when you stick it in the tailpipe, the dpf is likely damaged.

There are ways to protect the DPF when using the PTO extensively, but it'll require wiring stuff to the ECU and a trip to the dealer for some ecu customization.

Your current problem is likely a blockage in the fuel supply system. I would comb through that very thoroughly before condemning any parts .

 

[Yurik]

I did auxiliary tank test and had CEL come on when I was climbing up a hill on highway.
Got it connected directly to the pump.
The fuel in that tank was so hot I thought it would melt that plastic.
So next thing is the pump I guess?

 

[greasytshirt]

Unless there's a restriction in the inlet fitting, it sounds like pump failure is likely.