Did some more testing. Here is what I noticed.

With the engine cold, pressure relieved, tester connected and then key on, engine off, the pressure is around 7-8 psi. Engine on, pressure jumps to 28-30 psi idling.

With the engine warm, key on, engine off, the pressure sits about 36 psi. It jumps to 38psi then backs down to 36 psi within a half second. Engine on, the pressure drops to 28 psi.

If I rev it or drive it around, the pressure jumps to about 35 psi when accelerating but drops back to 30 psi when coasting.

I'm letting the truck cool down now. Is there anything else ya'll think I should check before I return this kit? Does it still sound like the regulator or have I disqualified that part?

Thanks again for your time and help!

-- Jess

 

THe engine off 5 minute test resulted in 37-38 psi.

I did go from 17 lb (or maybe it was 19, I can't recall) injectors to 21lb injectors. Is it possible that with the pressure at the minimum, it just can't feed enough fuel into those slightly larger injectors?

 

Also, disconnecting the vacuum line from the regulator raises the pressure about 10 psi as it should per the manual.

 

I know, I post a lot but I want to try and provide all the information possible.

One more thing I noticed, and I'm not even certain its an issue. I know that we tend to "overhear" things when looking for problems. But here is what I hear:

When driving at a steady speed (not foot off gas), I hear a low whistle. Now, I've heard that for a long time and I always associated it with the air intake (at one point I had a CAI on but I removed it when I changed the plugs, injectors and coils). I can really only notice it inside the cab.

I also notivced a sort of hissing noise tonight when the engine was hot and idling. It seems to come from the middle of the intake though I can't really pinpoint it nor can I tell if its an actual issue.

BTW, long and short term fuel trim is between -2% and 5% which seems to be within tolerence, yes?

Thanks again!

 

Well, I tested the fuel pressure again this morning after the truck sat all night.

KOEO - Pressure sat at 37 psi. With engine running it sits at 30 psi. It doesn't flutter or even move when the truck is misfiring. When accelerating, the pressure increases and holds steady at that PSI until you either accelerate harder or let off the gas, then it goes up or back down to 30 psi.

I pulled plug one just to check to see if it was still torqued correct and what it looked like. It was still torqued to 12-13 ft/lb and when I examined the plug itself, it looks like theres a bit of black buildup around the rim and the (is it the electrode over the nipple? I'm not sure, but the arched part anyways) is sort of a whiteish color. Would seem to me that the plug is getting overly hot. It also smelled slightly of gas but them I would think it should -- correct me if I'm wrong.

Well, thats about it for this mornings testing. I'm considering replacicing the manifold gasket but I do0n't know if thats the issue or not. A lot of work if I'm wrong.

 

The PSI should be 28-45 at any given time. You have sufficient PSI which is why I figured the pump is not the problem. The large swings in your PSI reading is what's focusing my attention on the regulator. A clogged fuel filter will cause a drop in PSI as demand go up, such as during acceleration. But in your case, the PSI is increasing during acceleration. Lower vacuum causes the regulator to open up and supply more PSI, which is why the PSI reading goes up when it's vacuum hose is removed. So in that sense the regulator is working because acceleration results in low vacuum and higher fuel PSI. But like I said, it's the large swings in the reading that I'm focused on, leading me to believe the regulator isn't working smoothly.

 

Hmm. Negative. Changed the regulator and no change.

 

Going to toss out a few more things I observed today.

First, I noticed that when I shut off the engine, I hear a 'shhhhh' or depressurizing noise. Unfortunately, since I'm the only one here I can't really stand by the engine and shut off the vehicle at the same time (now if I had a keyless start...). I can't say I've noticed that before but I was poking around and maybe I knocked off a hose (but I'd think if that was the case, it would run different).

The tail pipe drips a lot of water. IN about 10 minutes I had a puddle about six or 8 inches in diameter. I always attributed this to it just being cold outside in these parts but maybe its a sign.

I can't identify the smell from the exhaust other than maybe its sort of like melted plastic in a fire. Maybe. The exhaust fumes themselves.. well, its a white smoke and its fairly moist. If I hold my hand near the tailpipe for a few moments, my hand will be damp. It doesn't smoke like an oil burning type smoke but more like what you see on a really cold morning wen you start a vehicle.

Using a propane torch (unlit) I went around to as many places as I could reach in the engine to see if the RPMs would change. I didn't notice anything but then again, until the engine is good and hot, the RPMs fluctuate a lot.

Once the engine has been running for 10, 15 minutes, the RPMs will settle in between 690 and 710 while in park and a bit less when in drive. While in drive they tend to fluctuate more though. Probably a good 50 - 75 difference between high and low.

Here is what I don't quite get and it seems like it should be some sort of hint.

If I drive the truck when the engine is cold. For instance, when I leave work at 6am. It'll run like crap. No power, hesitates and stumbles when accelerating, shakes, jerks, misfires like mad (as I said earlier, I had 400 misfires in 2 minutes on a cold engine).

After it warms up, after 10 minutes or so of driving, it runs A LOT smoother. It'll still hesitate and stumble when suddenly accelerating (from a stop light, for instance) or if I really step on it to gain speed fast it'll stumble but then catch up and go.

I notice that it seems to do it less after its good and warm if I shut the truck off and then restart it. I haven't 100% verified it but that seems to be when I notice it the most. Typically, I think, because it was running like crap before I stopped at the store or whereever and then when I get back in to leave, it runs much better.

So, what would cause it to run really, really bad when cold but run with far less misfires when its warmed up?

I don't really have the extra resources right now to pay someone to smoke test it for leaks. I did hear theres some sort of dye you can run through it that'll leave behind a residue that you can see with a special light. Anyone ever tried that before?

Thanks again for your time and input. I'm really trying to test everything possible to find the problem. I appreciate any and all ideas.

-- Jess

 

1.) A vacuum leak on bank 1. Especially in the first minute or two after cold start when the HO2Ss are not up to temp. When they come up to temp and it goes into closed loop the ECM will try to compensate for the extra air (and will set the P0171 if it jacks the fuel trims up over ~30%).
(Use your Elm 5 or Scan XL to compare the fuel trims for Bank 1 and 2.)

2.) Maybe a problem with the IAT sensor?. Will your Elm 5 or Scan XL let you look at the IAT PID? It should read prety close to ambient when you first start up.

 

Hello again,

So here is what I've done recently.

I removed all the plugs, coils and injectors. Inspected them, cleaned them up again (the plugs had a bit of black carbon around the ridge, which I expected but other than that, looked almost new).

I dropped an extension and when I was under the truck, I noticed that the drivers side oxygen sensor (pre cat) was messed up. It looks like someone damaged the wires at one point, either melting them or whatever. I'm not sure, theres a pretty big dent in the sensor also from something pointed. Apparently in an effort to save money, they used some caulk to seal it up. The caulking was falling off and hte wires exposed. Figuring that was a problem, I replaced it.

Needless to say, the truck runs WORSE now than it did before. Now I went over an overpass and in the half mile to the top from the stoplight, I barely reached 30 mph.

I'm going to plug in my laptop and take another reading or two, then I'll start a new thread. I hope someone had some ideas again. I'll post the results of the log file.

BTW, IAT was at ambient and trims were within 5% (-2% to 5% for short and long term).

 

I have a 2000 Expedition, 5.4, now with 209K on it. The last time I posted on this thread was this past January (2010) when the Expedition had 186K and I was hunting down a vacuum leak to cure some bad mileage and the P0171 and P0174 codes. On that occasion the problem turned out to be the PCV grommet. You can look at my January post to see what else I tried before I got to the grommet. I got the P0171 & P0174 back a couple weeks ago along with a very rough idle and decreasing mpg so off I went on another frustrating hunt for a vacuum leak. I changed out the fuel vapor vacuum line because it was pretty deteriorated and also changed out a few connector hoses on some of the t-fittings on the smaller vacuum lines. I shot a can and half of carb cleaner on the vacuum lines to see if I could find the leak that way. Never found the leak. Today I decided to pull the IAC and clean it since I had never cleaned it before. I shot it with and soaked it in enough carb cleaner to start my own super fund cleanup site only to find that the spring was not holding the plunger in the down (open) position. No amount of cleaning was going to cure it. Since it was Saturday and all the local Ford stores' parts departments were closed I decided to go aftermarket for the IAC. I looked at the Duralast one at Autozone and the BWD one at Advance Auto. They looked identical and both said "made in USA" on the boxes. Probably made in the same plant. I bought the BWD one because it was $10 cheaper ($42). I installed it and it cured the problem. The moral here is that I had the exact same symptoms as a vacuum leak with an IAC failure. I had the rough idle, lousy mileage and the only codes it threw were P0171 and P0174 and did that about every 150 miles after I cleared them. I wasted a lot of time looking for a vacuum leak when it was the IAC. So if you have what appears to be a vacuum leak and can't find it and you've never touched the IAC before, you may want to think about pulling the IAC.

 

Thanks Gumbel for the idea. I'm still trying to find my problem; doesn't seem to be a vacuum leak of any stripe. I haven't sprung for the MAF yet, but mine seems clean and when I 'play' with it while the truck is idling, it does respond to changes in the airflow.

I am not so concerned about trying the IAC as the problem is not quite as much an idle problem as it is an acceleration issue. If I really 'floor' it, the trans kicks down, the engine revs up, and the missing abates. It doesn't always go away completely though.
So, if the fuel delivery was really an issue, wouldn't more demand for fuel exacerbate rather than ameliorate the issue?

Next tests: fuel filter and pressure check. The smart money seems to be on the MAF, though. I'm guessing it is out of spec, but still working somewhat.

 

Turned out the IAC valve replacement did not cure my vacuum leak problem (see previous post). My Expedition ran much better for about the first 150 miles after I put a new IAC valve in, but then the 171 and 174 codes and the rough idle returned. I pulled the intake butterfly valve off the throttle body, cleaned it thoroughly and shot a can of carb cleaner into the rest of the body (that I left attached to the manifold). I would have pulled the throttle body but it was late in the evening I thought I might mess up the throttle body & egr gaskets and didn't have replacements. The Expedition now idles better than it has in a while, but I still have the 171 and 174 codes. I have tried shooting carb cleaner and soapy water on every vacuum line with no luck. I shot soapy water where the master cylinder joins the brake booster and it appears to have some suction there with no brake pedal movement. (It also blows bubbles when brake is depressed and sucks in some bubbles when the brake is released.) I don't have a brake light or brake problems, but I am getting a sucking/whistling noise when I release the brake peddle so I think I have a brake booster vacuum leak. I don't want to continue trying to cure my vacuum leak by replacing parts, but the booster looks like the next candidate. Any thoughts? With 210,000 miles I'm hoping the plastic intake manifold has not cracked.

 

I replaced the brake booster (see previous post) on my 2000 Expedition 5.4 last night after convincing myself that it was the source of the vacuum leak. $160 (Motorcraft via Amazon, free shipping and it was here in two days) and an hour's work later I still had the problem. My Expedition actually idled worse so I figure I disturbed something but couldn't find anything wrong. I had become tired of guessing and it's too expensive to keep replacing stuff that's not broken, so it was time to go to Ford and have them diagnose it. I had the day off today so I took it in and paid for an hour of troubleshooting. They came up with a leaking intake manifold gasket at the bottom edge of the intake manifold where it mounts to the head. They basically shot carb cleaner while watching the computer readout and saw a spike when they hit that part of the manifold. Ford said they've seen this before and that it's always been the intake manifold gasket and not a cracked (plastic) manifold. They want 5 more hours + parts, or around $570 in addition to the $75 I spent today. There's a workshop manual posted online for the intake manifold gasket R&R at http://ww2.justanswer.com/uploads/bo...expedition.pdf . Looking at that, I think I could do it, but I'll probably pay Ford and save the aggravation (and have the work guaranteed, which mine is not). It looks like an all-day job for me if everything goes right, which it never does. (The exception would be the brake booster replacement last night, which went in easily because I probably didn't need to replace it in the first place.)

 

Looking at my last few posts in this forum you'll see I've been chasing a vacuum leak on a 2000 Expedition 5.4. I gave up and paid the dealer to diagnose it and they came up with the intake manifold gasket. I decided to have the dealer do it since I didn't want to risk doing all that work and still having a manifold leak. Last week they told me the gasket kit had arrived and I could drop off the truck. I did that Wednesday evening. Thursday they called to say that they had ordered the wrong kit (4.6) but would have the 5.4 kit on Friday. I told them that was OK and that they could disassemble on Thursday. I guess they waited until Friday to disassemble because on Friday at 2 pm they called to tell me the intake manifold was cracked. I would have bet that was going to happen after having read some postings on those plastic manifolds but the dealer had told me that 90% of the intake manifold leaks they saw on 5.4s were from the gasket. I told them to order the manifold, which they should have on Monday. The Motorcraft intake manifold was $484 retail but they're selling it to me for $386. I'll be into this for $1100 by the time it's done. Had I do it over again, I would have attempted it myself with an aftermarket manifold (Dorman, $166 on Amazon). The gasket kit is about $75 from Ford, but I think the Dorman manifold comes with a kit (gaskets and bolts). This is the first major repair this Expedition has had in its 211,000 miles so I probably shouldn't complain (too much) if this ($1100) fixes the problem.