Jeep 4.6 Fuel Starvation

[Jrama403]

So my new 4.6 Stroker has fuel issues and the problem is not obvious so any input would be great.

2004 Jeep 4.0.....errr 4.6

I have these injectors
https://fuelinjectorconnection.com/prod ... r-27lb-set

These injectors fit/work, are they correct??

Tested the fuel pressure it buzzes back and forth 40-50 PSI at idle. Idle to 5K (no load) I have constant fuel pressure of 45 psi. After 5 mins it does not drain below 30 psi ( so it not strong but within spec apart from the idle fluctuation)

Engine is running Lean (Snow White plugs!) and it will cut out above 3500 rpm full throttle, half throttle etc.

Suggestions?

[SkylinesSuck]

Need more info. What do you mean by cutting out? Do you have a wideband?

[Jrama403]

Cutting out means it will stop accelerating, and basically buck (deceleration) (kinda like hitting rev limiter but more pronounced (not something you want to experience on a motor being broken in)

So it will cut back (buck forward) then kick in again 75% power then cutback (buck) no sounds just plain fuel starvation. We checked timing with scan tool and the ECU is running between 10-13 degrees advance at idle (which is on the low end but in spec-ish) for a 4.0 atleast ..idle is a bit rougher than stock but ok...

RIght now (after fuel pressure test) everything is on the table (pump, throttle position sensor, regulator, o2 Sensor??) (tps is showing 13% open at idle via scan tool) My tach says idle slightly below 500 ECU is showing 650 so thats also just fantastic. (sarcasm) I am getting no CEL. Don't have wide band 02 sensor to measure a/f ratio. Will have to look into it but the white plugs tell the lean story.

Right now top suspect is pita fuel pump (its lived a hard life, previous short in wiring, evap line was broken and may have sucked a little dirt in on trail) But the pressure test seems ok so.... Before dropping the tank and spending the $$$ It would be good to get input.

Cheers

Jim

[grainofsalt]

Have you checked your coil and spark plug wires? Timing chain isn't loose?

[Jrama403]

Uses a coil rail and everything is nice and tight, timing chain better be as we just installed it last weekend

[Jrama403]

So it will cut out at 3500 rpm regardless of throttle position, but will rev to 5K at idle no load.

[TheXJway]

Ill be following this thread as my new to me 4.7 is doing the same thing. I'm ordering a wide band this weekend so I can see what it is doing and when. Good luck and post some results.

[Jrama403]

Yes no load 0 to 5k no issues, under lany load even 1/3 throttle no dice getting over 3.5k.

One odd thing I noticed is that on start up it will blip up to 1500-1800 rpm and the come down to normal idle (kinda reminds me of a small vaccum leak that gets compensated for) or is that just normal.

[Jrama403]

So we found the issue...

Turns out the Camshaft position sensor was "dirty" had some oil/grime inside. Cleaned it out runs great. Only concern is that there should not be any oil there in first place!... oh well its a step forward.

We got the hint after P1391 and P0340, what do they have in common? The camshaft sensor. Odd things is these codes did not occur initially but after a little driving.

Anyways Jeep pulls to redline with good power no issues now...until oil gets in the sensor again.....