J57ltr

Hello,


I am having an issue with a 06' 4.6L and it can't even get out of it's own way. We have had this truck since it was new and never really had any issues with it. I have replaced 2 batteries, a full set of brakes, an alternator and had to clean the Throttle body once over the years, but nothing really major.


Here in the last month or so it has had a marked reduction in power. I can floor it from a stop and it won't even chirp a tire in the rain. It will run up through the gears as if everything is normal but it's just REAL slow. I can stand on it and it will downshift and really has no power. There isn't a hint of a miss at all just slow gradual acceleration.


I recently drove between Houston and an hour the other side of Austin. I drove through a patch of road that had been ground down in preparation for new top layer to be added. After that it seemed even lower on power or I was climbing in elevation even more. As you get on the other side of Austin the elevation climbs about 2000'. So as I get into the hills it starts pinging and I decided to put some super unleaded in it. thinking I may have picked up debris from the tank from the rough road and may have clogged the fuel filter. The pinging went away and I assumed I was running slightly lean under power. The farther I go up the hills the worse it gets. I decide to replace the fuel filter as it's really bad. I pulled over bought a new filter replaced it and ended up driving back as it only seemed to help a little. I didn't have my scanner with me so I was just guessing. Here is the information I have gathered in the past few days.




The timing drops to -15* (15 degrees After Top Dead Center) and the fuel pressure seems normal 65psi but I don't recall how much it changed it did drop near the top of 2nd gear gut AFR seemed still rich.


The fuel trims are always rich on the Long term it's about -7%


The short term is mostly rich. but does fluctuate +/- several percent.


Just barely adding power causes the timing to plummet from 30's down to single digit timing. Full throttle I only get 75% throttle.


MAF usage seems to be in the 1100 CFM range.


IPW seemed about normal.


O2 switches and looks normal, if I step into it, rich if I let out lean then back to switching.


Torque Pro doesn't seem to be able to read Cylinder misfire or history, but does have a balance Rate, but only goes to cylinder 5. 1-4 were 0 and the 5th was something like 325% or something. Numbers 6-8 were not on there for some reason.


There are no codes stored.




Any help would be much appreciated. I don't know if the Throttle body needs to be cleaned or not, since it's actually firing ATDC and that usually means that the PCM is pulling timing.


I can't think of anything else that would be helpful


Jeff

650NutKase

Start with the basics. Has the truck had proper service intervals? Plugs could be fouling, cats may be starting to clog up. Is the MAF sensor clean? Start eliminating one at a time.

J57ltr

It's due for plugs, MAF has been cleaned there is no rotten egg smell or any thing else that would indicate clogged cats. I have looked at the basics that's why I am here. I was planning on changing the plugs this week when I get a chance, but if it were plugs there should be a miss that is detectable and it's not going to pull all timing just off idle at 15-16" of Hg for a miss I should be able to detect, it should also show as lean if it was missing wouldn't it?

The pre and post cat O2's look like they are good with the post cat being slower in it's switching response than the Pre cat O2's.

The only thing I didn't mention is when I did remove the fuel filter what came out was brown. I would expect this to clog the injector screens, but it's still running rich so that doesn't make sense.

Also why if I command 100% throttle it only allows 75%?


Thanks,

Jeff

J57ltr

Any other suggestions that could cause the issues I am seeing? New plugs didn't help. it's got a new fuel filter and fuel pressure seems normal. The MAF is clean and has a new airfilter.

Thank you

Jeff

650NutKase

Have you tried resetting the PCM by disconnecting the battery and draining the capacitors? FordTechMakeuloco has a video on this. Also, is the intake tube intact and properly sealed? A leaking or loose tube could allow unmetered air to enter the engine and make it run like crap...

J57ltr

I'll give that a try but I am skeptical that is going to make any difference. The engine runs fine it gives no indication that something could be wrong other than the lack of power. The engine doesn't run like crap it runs fantastic with the exception of the lack of power for passing, it won't even squeak a tire. The truck idles fine and I have been through all the normal troubleshooting It pulls 17-18" at idle, it idles at 15* of timing in gear. It's perfect, but it limits me to 75% throttle and sets the timing under load ATDC. Why is it pulling timing and why is it limiting throttle?

650NutKase

with the PCM reset, it'll allow the computer to relearn fuel trims and throttle position. I'd give this a shot. Only takes about 15 min

J57ltr

Ok here's the deal. The fuel trims being negative mean that the truck is running rich and should not effect timing one bit. This thing not having any power should not have any impact on anything that would be reset by the battery being disconnected. As I suspected it didn't do anything at all and the same symptoms are still there. Any application of throttle drops timing all the way to -15*. Now I am no newb when it comes to working on vehicles. I am tired of chasing my tail here with wild goose chases. Is there anything I can check that would be relevant to the actual problem?


Again I disconnected the battery, I have changed the plugs (they needed it but weren't so bad they would cause the issues I am seeing). MAF is clean, TB is clean, and I am not getting 100% throttle and I am getting -15* of timing at full throttle (75%). What in the wild wild world of sports is going on with this thing?


Thanks,


Jeff