Rick's 06

He had fuel filter on his list of things done.

Summers22

iTrader: (2)

Oops missed that. I am betting on clogged cats or fuel pressure regulator.

Fastcar302

I already changed it.

Fastcar302

This is a returnless style fuel system. There is no pressure regulator. The ECM varies the voltage to the fuel pump by way of the FPDM to control pressure.

Fastcar302

I've been working a lot of hours and haven't had much time to tinker with the truck and my SCT Livelink software won't connect to my X4 for some reason so I can't get a good datalog. I used another handheld scanner to view some live data and found the following information:
-Long term fuel trim is -29% on both banks
-Fuel pressure stays between 39-45 psi
-Upstream O2's both have sin wave signals(normal)
-Mass air signal is reading about .7 lb/min at idle

This is not a complete list of data, but it does tell me a few things. The long term fuel trim is negative so the ECM is trying to remove fuel because it's sensing a rich condition. Since the upstream O2's are both reading the same up and down pattern(like a sin wave), I don't believe the problem is being caused by a faulty O2 sensor. The constant fuel pressure throughout the RPM band tells me the pump is working fine and there is not a lack of fuel flow, which makes sense since it's running rich. I'm leaning towards a plugged up exhaust or cmcv plates malfunctioning. I'm not sure If I have some time tomorrow after work I'm going to put a laser thermometer on both sides of the cats to see if there's a big temp difference as this would indicate a restriction in flow. I've used this method before and it worked great. I'll keep everyone posted as I continue to make progress.

Meanwhile, does anyone have any other ideas what could be causing the ECM to be receiving a rich signal?

jwmustang

How about a faulty engine temp sensor or poor temp sensor connection.
For example that would change fuel/air mix to wrong levels if it thinks its cold when it is really warm.

jdinner

That should trip a P0113 code if it was the case. And, correct, it would be running really rich.

jwmustang

I had a van that had that sensor bad that never showed a code, and it turned out it was that sensor. I think it was because it was an intermittent problem so it never through a code.
Only reason the tech found it was because he just happened to be looking at his diag tools when it acted up for a couple of seconds and he happened to be watching the temp at that time. The car gauge never changed because its analog and reacts slow but the computer input which digital is instant so the computer will make changes fast.

Fastcar302

I have an accurate reading on the temp sensor. I checked it when I was collecting live data from my scanner. It read from ambient on up to 195 or so when it was idling. Also, I should mention that TPS is out of the question too since these electronic throttle bodies have two TPS that mirror each other and if either one is malfunctioning the computer will throw a code instantly and display a wrench light on the dash. It's a very closely monitored system since it's "drive by wire."

I put the thermometer on the exhaust today and measured the temps before and after the cats and resonators and the readings were all even once it idled for about 10 minutes. I'm still not certain the cats are good, so I will pull the exhaust off tomorrow after work and do a good visual inspection. I did drive it a little bit today and it now worsened to bogging when under any load to the point that it won't rev above about 1800 RPM or so, which is very typical of a clogged exhaust. I'm going to figure this problem out and post my findings so I can hopefully save someone else the grief of what I'm going through right now. This damn truck is not smarter than me.

jdinner

This is the story of my converters...
https://www.f150forum.com/f4/06-5-4-...-fires-291476/