Hi everyone, I could really use some help with my rig. This is my first post, like most long time lurker first time poster lol. I've searched and search even beyond this site and can't really find a definitive solution.

So for starters, it's a 97 expy, 155k, 5.4, 4R100, Eddie Bauer, basically every option except air ride as far as I can tell.

My issue is sluggish acceleration and a loss of 2-4 mpg on average. It guzzels during any thing that resembles acceleration, 2mpg for example. At 3/4 throttle it sounds like it's accelerating, but it's just not getting anywhere. If I'm at a steady throttle and give it a little peddle it seems like it wants to go, but then falls on its face and feels like it shifts up. This is the worst between 35-55 like most others ive seen with similar issues. It idols fine. Cruizes fine. It's basically just the mpg and acceleration.

The rig was given to me by my parents who apparently thing cars are disposable and not to be maintained except oil changes. So.... I've spent an inordinate amount of time bringing it back to "normal." I've done the following in the last three months.

Fuel filter
Trans fluid and filter
Oil change
Gotts mod
Cleaned MAF
Removed intake silencer
Ran a tank with seafoam
Replaced an 02 sensor(out for years) to fix a CEL
Replaced Exhaust manifold with shorty headers to fix CEL
Replaced EGR tube due to manifold
Replaced EGR valve due to stupidity removing old EGR tube
Replaced fuel vapor hose on intake elbow(rotting out)
Replaced a COP due to car wash(trying to clean off some oil to locate oil leak)
Replaced serpentine belt
And a few other non engine related items.

All of this was done before my issue came about and all CEL's went away and none have resurfaced. The issue doesn't seem to be related to any of the items mentioned since it started running a lot better for 2-3 weeks and just all of sudden turned into a turd.

Here are the items I've already tested or think I've tested properly.

Had an exhaust shop check the cats and exhaust. The said I have a slight restriction on the driver's side, and that it is probably breaking up, but they said it wouldnt account for the sluggish performance.
I've also test the fuel rail pressure and its 35 pre ignition, 30 running, spikes to 38-40 under light throttle and it doesn't bleed down when key is off.
Manually tested fuel pressure regulator and it seems to be working.
Tested EGR and it stalls when vac line is removed.
Tested dpfe with multimeter and it checks out.
I know I've tested other items. But I can't recall what else at the moment.

I also have torque on my phone due to this rig giving me these issues. So i am fairly confident it's not my COPs since I've been monitoring individual cylinder misfires and I'll see maybe one in a half hour of driving and its always a random cylinder. I was able to get the mode 6 tests and will attach those results in a second post. One of two tests fails which is either 41/11 or 41/12, usually 41/11 though, but I haven't really been able to find a definitive answer as to what that test relates to.

To say the least I'm fresh out of ideas at this point and could really use some help. And no I havent done plugs and don't know when they were done last or if ever, but they scare me cause I've heard it's ez to break them. Sorry for the long post.

Help please!?!?

Thanks in advance,
Brett

 

Mode $06 report generated by Torque for Android
================================================

Vehicle VIN: Not present
Vehicle Manufacturer: Unknown
Vehicle Calibration ID: Not present

Unit and scaling information are not supplied with the data from the ECU for this type of vehicle. Consulting the manufacturers service book for this information is recommended.

Test report:
------------------
TID:$01 CID:$11
- Rich to Lean sensor threshold voltage(constant)
Min: 512
Test result value: 804
PASS
----
TID:$01 CID:$21
- Rich to Lean sensor threshold voltage(constant)
Min: 512
Test result value: 805
PASS
----
TID:$03 CID:$01
- Low sensor Voltage for switch time calculation
Min: 0
Test result value: 461
PASS
----
TID:$03 CID:$02
- Low sensor Voltage for switch time calculation
Min: 0
Test result value: 512
PASS
----
TID:$10 CID:$11
-
Max: 48
Test result value: 47
PASS
----
TID:$10 CID:$21
-
Max: 48
Test result value: 47
PASS
----
TID:$41 CID:$11
-
Min: 63,744
Test result value: 35
FAIL
----
TID:$41 CID:$12
-
Max: 896
Test result value: 35
PASS
----
TID:$45 CID:$20
-
Max: 14,388
Test result value: 8,192
PASS
----
TID:$4a CID:$30
-
Min: 768
Test result value: 2,342
PASS
----
TID:$4b CID:$30
-
Max: 26,214
Test result value: 18,231
PASS
----
TID:$01 CID:$11
- Rich to Lean sensor threshold voltage(constant)
Min: 512
Test result value: 804
PASS
----
TID:$01 CID:$21
- Rich to Lean sensor threshold voltage(constant)
Min: 512
Test result value: 805
PASS
----
TID:$03 CID:$01
- Low sensor Voltage for switch time calculation
Min: 0
Test result value: 461
PASS
----
TID:$03 CID:$02
- Low sensor Voltage for switch time calculation
Min: 0
Test result value: 512
PASS
----
TID:$10 CID:$11
-
Max: 48
Test result value: 47
PASS
----
TID:$10 CID:$21
-
Max: 48
Test result value: 47
PASS
----
TID:$41 CID:$11
-
Min: 63,744
Test result value: 35
FAIL
----
TID:$41 CID:$12
-
Max: 896
Test result value: 35
PASS
----
TID:$45 CID:$20
-
Max: 14,388
Test result value: 8,192
PASS
----
TID:$4a CID:$30
-
Min: 768
Test result value: 2,342
PASS
----
TID:$4b CID:$30
-
Max: 26,214
Test result value: 18,231
PASS
----
TID:$01 CID:$11
- Rich to Lean sensor threshold voltage(constant)
Min: 512
Test result value: 804
PASS
----
TID:$01 CID:$21
- Rich to Lean sensor threshold voltage(constant)
Min: 512
Test result value: 805
PASS
----
TID:$03 CID:$01
- Low sensor Voltage for switch time calculation
Min: 0
Test result value: 461
PASS
----
TID:$03 CID:$02
- Low sensor Voltage for switch time calculation
Min: 0
Test result value: 512
PASS
----

End of report.

 

Change the plugs, they don't break. You are thinking of the 5.4 3 valve plugs in the 04-08 vehicles. Motorcraft plugs, no antiseize, 28 ft/lb torque.

 

Well that's a huge relief! Thanks for the correction. And I have read that this motor is picky when comes to the ignition system so the COP I replaced was motorcraft. In fact I purchased motorcraft plugs and returned them before this issue came up because I was freaked out by the plugs. Hopefully it's that simple. And thanks for the tips on torque specs and antiseize.

I do have a couple additional questions though. I seem to recall that the fuel rail may need to be removed to get all the plugs out, should I buy new injector o-rings for reinstalling the the rail?

And does anyone know what that mode 6 test fail means? Or where I can look it up with out buying a membership to Ford service?

I'll update once pluggs are done.

Thanks again.

 

New motorcraft plugs are in. Some plugs were finger tight, which was awesome. It idles smoother, seems quieter, but no real difference. Milage is still crap as well.

 

Restricted cats can definitely cause poor performance and mileage.