The rail pressure is between 4.3 and 4.5 at idle in park. Rail pressure is 25 ish full throttle at highway speeds and rail pressure is 15ish at full throttle in park. The injector balance difference is 5 at idle in park and 6.5 with the foot on the brake and in gear. Anything else I should look at?

 

the rail pressure looks to be fine then from what your seeing.

that one injector on the other hand is out of specs. its only one injector doing that to you?

 

When I said the injector reading was 5, I mean the difference between the highest injector number and the lowest injector number. At idle the low is -2.2 to +2.8 and in gear with my foot on the brake the low is -2.7 to 3.8.

If I am travelling at 65 mph and I put the truck in neutral (testing it on a long coast downhill) the engine rpm's go up to about 1900 and the boost will not go below 2 psi even though my foot is off the accelerator and it may me a very long descent or coast. I have only been doing this "neutral coast" as a test measure, it is not part of my normal driving habits. Man my mileage sucks with whatever this problem is.

 

ok the injectors test out fine using a scanner then.

 

i think my is doing whatever yours is doing cause i cant get more that 12mpg out of my. It is only stock with a k&n and a dully 3500 but i have done that before the coasting and the rpms stay the same if not go up. I just figured it was a dmax/allison thing.

 

I have a idea on what your problem may be. As i posted earlier i was getting horrible fuel mpg. Over the weekend my truck threw its first code. It was a P003a which is the vane in the turbo. The vane controls your boost. But to start back at the beginning. My truck when i got it was getting about 11-12.5 mpg also when my truck was at ideal it would change sounds kinda like the A/C compressor was kicking on. I assumed these where normal for a Dmax. Further down the road now I got this code. I am now have the turbo rebuilt by fleece performance. After the code it kinda all made since. My valve has been sticky for a while (not enough to send a code) which was causing the bad fuel economy. I have not fixed the problem yet so I can not say much of the after math yet but I will repost after i get the rebuilt turbo in.

 

What kind of additives are you using in it? The reason your turbo isn't going below 2 when you are coasting down the hill is probably because of your rpm's being at 2000. If i were you i would take it to a diesel specialist and talk to them. It would even help you to talk to them on the phone. Most of the time dealership mechanics are not specifically great with the dmax. So ya just call a diesel specialist and talk to them about it, don't screw around with the dealership
Wyatt

 

Are you taking the boost reading from the edge? Get a gauge because the obd is always wrong. I can hit 30psi if I look at the obd. And 22 on my calibrated gauge with no leaks

 

the OBD2 adds its boost readings to the normal atmospheric pressure so it will always be higher then the add on gauge

when putting the truck in neutral while going 65mph the ecm will keep the rpms up so as to match the wheel speed and re-engage the gears smoothly when put back in drive at speed

personally i think it is ether the turbo vanes are sticky/stuck or it is suffering from high exhaust back pressure, ie: clogged cat. the latter happened to me and my MPGs went down the drain. removed the cat and the MPG was restored. my boost pressure was also acting funny too. having to push the engine harder to over come the back pressure. it seemed to run fine to me except for the slightly slower spool up and crap MPGs

granted mine is not a VV turbo but i think the theory still applies.

balance rates & fuel pressure look fine to me. i dont think most dealers know about the vane issue. later year models had programming in the ECM to cycle the vanes while at idle to help prevent them from getting stuck.

 

I vote for exhaust getting clogged