Thanks again guys.. the codes are the ones related to lean banks 1 & 2.. I think you're all familiar with the exact numbers. I've seen them posted lots.

glc - fuel pump system issues?

I was wondering.. it crossed my mind the night this all started.. could someone put something in the gas tank (ie. the old sugar cubes trick) and cause issues like what I'm seeing? LOL.. funny story.. but there's someone I know who may have wanted to mess my truck up and while I'm not susceptible to paranoia.. one never knows. Just thinking of every possible reason that this would just 'suddenly' happen.

 

The FPDM is the module that regulates the fuel pump, it's on the rear axle. It's very subject to corrosion. Unplug and unbolt it, look at the back side. You can get a Dorman replacement for about 60 bucks.

Have you replaced the fuel filter?

 

I'm going to go out on a limb here and tell you that it's a vac leak. Lean codes means it is sucking unmetered air, as in the MAF didn't measure it but the O2's are picking it up. That tells the computer to start changing the air/fuel ratios and is probably why your idle is jacked up. Short explanation is the computer doesn't know how to make the motor idle.

Find and fix the vac leak and all should be good.

 

... and so forth, on NINE previous occasions (at least)....

^^^ You have GOT to stop saying this! Folks will never find it. Not having one is no excuse!

It's on a frame crossmember, behind the rear axle and above the spare. Spare needs to be dropped to find and access it.

OP - instructions here: https://www.f150online.com/forums/ar...placement.html


MGD

 

I'm with a few guys above if your getting lean codes check for vacuum leaks. It still wouldn't hurt to clean the throttle body and check the fpdm though. Nothing a wrong with preventative maintenance especially on things known to cause issues.

 

Great information guys, thanks again for responding. I will follow all of your advice and post results when this is all fixed.

Great forum!

Ty

 

So on this topic again.. I picked myself up a new code reader by Innova. A 3100ABS.. pretty decent off the shelf product. Ok so codes were the typical P0174/P0173 but I also got P0113 which is the Intake Air Temperature Sensor 1 Circuit High Input code.

So I got looking around for info on Intake Air Temp Sensor and sure as hell the local parts shop carries this thing 'for my truck'..

VIN code "5" .. 2004 F150 XLT 5.4L 3V

But wait.. the IAT doesn't come as a separate unit from the MAF.. like they used to be in the older models. So the local parts shop sells me something I don't even need.

My point in rambling here is to ask you guys.. would code P0113 be cause to consider the MAF/IAT unit malfunctioning in turn causing the lean codes and the truck to be running like crap?

 

Did you try anything since last post besides buy a code scanner and read the codes? Did you try cleaning the maf?

 

Yes cleaned the MAF with proper cleaner.. checked all the vacuum lines I could locate. Took the air intake off as well to make sure I was seeing everything in behind. That 90* vacuum line doesn't seem cracked but it is corroding .. probably not the source of a leak at this point but we will see this weekend.

The trouble right now is I'm on limited funds (aren't we all?) and so I'm doing what I can at the minimum costs.

With the P0113 code it did make me think that even after I had cleaned the MAF, if it wasn't functioning correctly that cleaning it wouldn't have made any difference. And there was no change in how the truck runs after. So it's either in good working condition OR it's a source of the trouble. With that code and the lean codes I'm only looking for opinions on whether that could be a direct link.

Seems as likely as a vacuum leak doesn't it? I'll be doing the smoke test this weekend so that'll help to rule out or confirm those suspicions.

I've picked up a new fuel filter which I'll be swapping in as well. The FPDM will be something I have to check into as well. I believe I understand it's location.. frame crossmember up in the spare tire area? I'm looking for corrosion? Any specific test I can perform on it to ensure it's functioning other than a visual check?

Saturday is a full diagnostics day for me.. will be swapping in a good coil on each plug to determine if there's one or more failing or failed completely.

 

Figure it out?

 

Hey Ross-FX4 .. if you mean your quick 'Fuel Pressure = THIS!' post then no lol.. and no since my last post I haven't done anything. I'm in the middle of my work day so the truck's parked atm.

Put it this way.. under normal driving the truck runs fairly smoothly. When I come to a red light the RPM's dive down to almost zero.. sometimes the truck recovers and sometimes it stalls.

So if you're suggesting fuel pressure then what specifically are we talking about here? Fuel pump? Fuel filter (have new one - replacing this weekend)? MAF/IAT not working?

I hate chasing ghosts and at this point that's what I'm doing

 

Maybe
Maybe
Maybe

FPDM. Unbolt it and look at the backside. Also unplug it and look at the connector.

 

Ha! Just my luck.. the damn tire iron is missing from the truck.. geeez.. I can't catch a break here LOL..

Ok .. so

Maybe the MAT/IAT
Maybe the Fuel Filter
Maybe the FPDM
Maybe the Fuel Pump

All high ticket items except the $16 fuel filter.. ok well we're going to see this weekend what's what and I'll repost. After each item has been tested I'll post results here for anyone else who's experiencing the same symptoms.

My brother's a Ford mechanic and he's always suggested a bad coil or maybe multiple coils are bad. All of these other items are also suggestions of his so I'm happy to see everyone seems to be agreeing on where to go with this.

Again, thank you for keeping up with me on this and all of the help so far.

Cheers
Ty

 

A Dorman FPDM is not that expensive.

 

Ha Ha Ha Ha you caught that.

I read the first page. Didn't realize it had two pages.

So I was 1 page out. Just carried on the fuel pressure theme.

Need to get a handheld and monitor fuel pressure. If its diving up and down IDE say FPDM. also check the MAF function. grams per something.