Ok this belongs to a friend of mine and it is killing me. It is one owner 297 k truck. This is first major malfunction. Currently missing on #8 cylinder. List of repairs, new orings on 8. 3 used IDMs 2 reman injectors on other cylinders. new fuel pump and filter. new oil change. new baro. left side UVCH and valve cover gasket. repaired bad connection on lt blue wire from IDM causing buzz test failure high to low. 2 new batteries. Little to no oil coming out of injector discharge on 8. Before this started it ran the same way but all cylinders would make a difference when unplugging them one at a time with VC removed. Have had them both off 3 times each. Originally would pass contribution test on all cylinders. It was too cold to day to get it to run. Help. Out of ideas!!!!!!!!!

 

oil mus not be reaching the injector

 

What is the ICP pressure and IPR duty cycle percentage? Number 6 and number 8 fire in sequence. You could be having a low High pressure oil problems. IS it a dead miss? or does it just fail a contribution test? Also does it by any chance have the new gray CPS in it?

Any CEL or codes?

 

also did you say you put 2 injectors in but on other cylinders??

 

When I first started on it I took it for short drive and seemed ok on accel but it could be I was not used to it. I drive same truck with 5.8. But it acted like amiss on decell and would die or almost die at stops and was missing badly. Brought it back and it passed the buzz test and the contribution test. Pulled pass side vc and it was hitting on all injectors at idle and under accell. seamed to mis on #5 o n decell so I changed that injector and seamed to make a difference. I did the same thing on the left side and changed number 4. Truck started good but missed after I took it off idle. At this time it was hitting on all 8 during idle but still runs rough. Did all the other repairs as stated and then had miss on 1 and 8. Swapped the number one injector with one I took out of number 5 and #1 miss code went away. Tried the same thing for #8 but did not help. Checked and it is Federal emissions and 8 is supposed to be the same. No help. Today I found bad connection in square connector between IDM and #8 and repair that. Now it passes buzz test but not much change when unplugging injector.

 

Has old sensor about 50k ago along with new o rings. Seams like dead miss but it did not have dead miss when it first started. Engine dies when IPR is unplugged and pressure is is in spec with WOT test.

 

does it seem to make any difference whether the engine is hot or cold?

 

When first starts it feels smooth but then goes away. Hot or cold it is bad.

 

This morning i drained fuel filter and filled it with CRC injector cleaner. The idle was better and you could feel a change in the idle with unplugging of the the 8 injector. I am off to buy new injector.

 

Remember you have to run it in after exposing the HPOP system to air.
It will stumble/miss until the air is purged. Run it hard on the road test.

Grey CPS?

Bill

 

Ok, I changed the injector and it is not missing on that cylinder (8) now but seems to be on 2. Is just just from air in system? Was not missing on this cylinder before last repair.

 

To get the air out you need to go out and flog that truck for about 20 miles minimum

 

Tonight I changed the weak injector on left bank #2 and now it hits. I changed the remaining three on right bank and it runs like a top. Turns out all the injectors were bad. I have worked on several of these and have had good luck with replacing one or two. This truck needed them all. Thanks everyone for there suggestions.

 

Good to hear! sometimes they just have too many miles.