6NZ low power question

Questions like this a hard to answer.

It could be a boost sensor.......you had to remove it from the old head to install it in the new head. Did you drop it?

You could also have the camshaft installed out of time, but you should have a CEL if you did.

Did you pinch the wiring harness on the engine with any tools while thew head was off?

The list goes on

You need to hook a laptop up while doing a test drive to monitor the sensor readings to make sure the engine is operating properly

 

just went through something simular ended up being wiring harness

 

Did you put the plug in the head underneath where the inake elbow bolts to the head? Also there is a smaller plug that goes behind the elbow for the supply line to the air compressor, did you put it in? Check the gasket on the air compressor where supply line goes in, they will blow out the bottom.

 

Did you install new ex sleeves in head, check ex wheel on turbo to be sure there is no damage from a seperated sleeve.

 

Possibly the wastegate on the reman turbo is hung partially open or maybe they gave you a mbn turbo on accident which has a weaker wastegate spring in it. Pinch off the wastegate hose and see if the boost comes up.

 

I had a customer awhile ago with a similar result after an engine swap. His problem ended up being injectors. He had someone swap the motors when his old engine expired. They took the injectors, camshaft and turbo from his motor and installed them on the replacement motor. Afterwards the engine wouldn't build more than 27 psi of boost, when this combination of parts was building 45 psi of boost on the old engine. He replaced a number of sensors and the engine wiring harnesses with no improvements. He ran the overhead and checked the cam timing twice that I know of. He had me tune the the ECM for the engine............he spent a ton of money trying to fix this problem. We both knew that the problem was related to the engine not receiving enough fuel to build the Hp it should, but everything checked out perfect. The injectors were installed in his original engine 6 months before it expired, so they had low hours on them when installed in the replacement engine..........how many times have you ever seen 6 injectors go bad at once? Everything that could be checked or replaced was to get this engine to build HP, yet it was roughly at 50% of its power potential

Finally in a last ditch effort to get the truck to run he replaced #1 and # 2 injectors...........now he had an interesting result with this



The engine would no longer pass an injector cut out test and it missed horribly when under a load..........he replaced injectors 3, 4 ,5, and 6. The engine returned to its normal power level, which was in the 850 Hp range.

My theory on this is the shop that had removed the injectors from the old engine and installed them in the new one...........soaked the injectors in some sort of cleaner, gasoline, something that washed the diesel fuel out of the barrel and plunger of the injector body.........they washed the only lubrication that was in this area of the injector body away. When the engine was trying to fire with a fuel system that had been drained of fuel, the barrels and plungers in the injector bodies got scored. All 6 injectors were bad and not pushing the correct amount of fuel through the injector tips into the engine to produce the Hp that the engine was capable of.

Now here's the questions you need to ask yourself............did you soak the injectors in a cleaning solution and possibly wash the fuel out of the barrels and plungers? Did you use the starter motor on the engine to turn the motor for a long period of time while trying to prime the fuel system?


Yes, if you damaged a wire in the harness, you should have a fault code in the ECM.