Guys,

Thought I would let you know what all I have done so far... and the results.

In my attempts to locate any kind of vacuum leak, I found two lines between the battery box and the firewall that were in pretty bad shape. Replaced them, but still the bouncy idle/floating miss. Still no codes at all.

I did find a potential issue with the HVAC system. I am trying to verify if the HVAC system acts like a closed system, or not. Mine seems to have a vacuum leak, (unless they all act this way). Isolated the system and can't seem to pull a vacuum on it, (unless running off of engine source). May end up pulling the dash to figure this one out. We'll see.

I replaced all eight spark plugs. Plugs had been installed for about 30-35K miles. They had quite a bit of carbon built up for only 35K miles. Also, the center electrode on many of them looked like someone had filed it off at an angle. Quite a lot of wear for plugs with such few miles. Truck seems to maybe run a little better... but still has the rough idle. I cleaned out the spark plug barrel area real good, like F150Torqued suggests and maybe I can get more miles out of this set.

I did buy a OBD reader that would allow live scans and some good mode 6 information since my old one did not. CAT temperatures appear to be alright, but I need to check them @ 2500 RPM to be sure. Short fuel trims are all over the place in both banks. Double digit positive all the way to double digit negative. Really radical swings I'm thinking, so I may be looking at some O2 sensors. But I'll check some more and let you know what I found out.

Any one ever investigate the PCV module much? I'm talking about the one that is held in with two bolts on the drivers side of the intake manifold. I think it is odd that for years and years, the PCV valve was always replaced if needed and could give some kind of issues, when acting up. Now it is not even a consideration.

Lastly anyone think of the MAF sensor? There are not very many sensors that provide the PCM input during open, or cold operation, but the MAF is one that does, if I remember right. Wonder what a slow, or lazy MAF is like?

I'll let you know more when I find out more.

Thanks.

 

I realize this is off the topic of my original post...

In light of the VW diesel scandal I was wondering if the same could be done to any vehicle that tuners are available for? Seems kinda genius in an immoral way...but could keep a higher mileage car on the road...

 

You guys (@kcward & @ Roadie) trying to make me nuts? Or just more nuts? I _think_ I have one OBDII sensor figured out (the oxygen sensor), and you go shake it up with a bunch of superior knowledge about the damn gadget (lol).

I have no work experience or educational background to base it on. Only readings from Torque Pro - which I must recognize is filtered through a bunch of software by the time I see it on-screen. But it seems extreemly important in diagnostics analysis of many different problems, so I un-argumentively raise the following questions.

How "wide" a fuel mixture "ratio" can the O2 sensor handle? If there is NO oxygen below 14.7 ratio, Would this not pose an difficult calibration issue where the output from the O2 sensor swings from .1v to .9v with the optimum output being .45v? Is this voltage swing "linear"? What extreems do .1v and .9v represent?



Again, my only reference is Torque, ie: the attached graphs. I cannot disagree with 0v = total lack of oxygen, but how do I reconcile that with the two attached Torque screen screenshots are at idle and/or very gentle driving and THEN FLOORBOARDED until closed loop dropped out followed immediately by full coast. ????? I know under floorboarded condition fuel trims go full bore, of course so does MAF ??? What is Torque telling us. There is MORE Oxygen in the exhaust - or overly RICH fuel with no oxygen????
BTW, @kcward - definitely if your "fore" and "aft" O2 sensors look the same - unfortunately that means your CAT is bad.







FLOORBOARDED until closed loop drops out - then immediate coast and then screen grab.





AT idle, or under very gentle driving - no appreciable load.

 

@Rocket_man


Thanks for the kind mention and vote of confidence concerning some of my posts - (this site doesn't seem to have "Reps" or "Thanks").



You are correct about this and it makes a 'flaky' injector a difficult thing to diagnose. And it IS a possible cause of a rough idle. One of the best (and perhaps only) method to diagnose it is to carefully label and keep up with each spark plug as they are removed. Analysis of the plug condition can reveal a lot about its long term operating environment - (ie: too lean, too rich, overly high temperature over extended period - or OIL burning.)


There is NO CAT "Temperature Sensor" on the Ford 5.4L (at least on mine).
The Scanners (including the Torque Pro App) will give CAT TEMP, but it is "calculated" from other OBDII sensor inputs. In some cases by the ECU uses several sensors and outputs information, such as CAT TEMP to custom PIDs, or in some cases it is calculated by the Scanner itself. IE: The '04 5.4L does not have an "intake manifold vacuum sensor". It is calculated by displacement, RPM, MAF air flow, barometric pressure - and god only knows what all else. I am not suggesting don't use CAT TEMP readings. Just be aware failures of other sensors / devices or other PID readings should be considered with it. [To pun, The CAT TEMP reading should be tempered with other factors. Lol]

What did you mean your FTRIM readings jump all over the place, and which ones read what. They should be pretty stable under a stable condition. Keep in mind, the ECU maintains a multi-dimensional table of fuel trims based on several factors like ENGINE RPM, ENGINE LOAD, THROTTLE POSITION, MAF. But at a steady RPM, LOAD, and throttle position - should produce a very steady reading. If NOT, why would that make you suspect O2 sensors.



That 'gizzmo' is not a PCV module or valve. In fact their ain't one. That 'gizzmo' is a simple electrical heater to heat the crankcase air drawn into the intake manifold from the drivers side valve cover. Filtered air is drawn from the right side of the throttle body through the passenger valve cover, out of the drivers side valve cover, then through the heater (activated by the ECU below about 40º ambient temp) into the belly of the intake manifold.


Lastly, a 'goofy' MAF can cause strange problems because its signal IS used in lots of calculations decisions by the ECU - such as manifold vacuum AND Charge Motion Control Valve (CMCV) positioning.


Thanks for updating and let us know what you find.

 

All,
Went ahead and changed out all of the O2 sensors... and they all appeared to be the original ones. Reset the PCM and been driving the truck around town. It seems to be more responsive, definitely quicker response from a stop using partial throttle. But the floating miss is still there.

I think I'll try a good cleaning of the MAF and see if that helps. Going on a couple hundred miles trip this weekend, so I should be able to scan some good data. Still no codes anywhere. I think I'm going to pull the dash soon, for some HVAC issues I am discussing in that forum, so this may get moved to the back burner.

Sometimes the miss appears to be right at cold start up, with no load. Sometimes it shows up at start up after the engine idles down, (cold or hot), still no load. Although I can't seem to feel it when idling in gear. Maybe the engine speed is just too low to really feel it...?

I'll keep poking at it.

Thanks guys.

 

I will just throw this out there because sometimes its just a brainstorming idea that solves a otherwise maddening problem. If the ECM is not receiving a consistent 12 volts from the battery it can/will start acting retarded and can can cause all kinds of engine function issues. You may have already checked this but just another avenue for thought. Good luck.

 

Are you suggesting that the altenator and battery I bought at O'reilleys are not operating properly? LOL!

I kinda remember checking voltage at the battery terminals running and off...I think I was getting 14.1 running, and the battery was at 13VDC or so with engine off...but that was a few months ago...I will check mine again...It is that time of year again...the temps start dropping and the battery dies...(time for my yearly battery change)...

Its kinda funny...my truck doesn't seem to run as bad when the temps are above 80 or so...

FWIW, I am passively trying to figure this out...about once a week I will take a look under the hood...It's still driveable...but today, the temp is around 65 and its running like s@*t...

 

We have 2 people getting help here now - the thread has been hijacked.

 

@GLC,
Actually there are three of us trying to figure out a very similar issue/problem. So I guess I'll respectfully disagree with your hijacking comment.

From my standpoint since my engine running rough issue is very similar to the kcward and F150Torqued and the vehicles are very similar, it made sense to me to add whatever help/comments I could to this thread. Seems to me it makes some sense to keep all of the comments and/or findings in a single thread especially since this seems to be a very elusive problem, or set of problems.

Of course I will default to the opinion(s) of the moderators and if we need to break this, then so be it.

Thanks.

 

I only said that because there are some replies directed to a specific person that aren't being interpreted as such. I don't think Dynotech's last reply was directed to kcward.

 

To add insult to injury...

I just lost overdrive in my truck...I hope it's the OD snap ring..at least that would be an easy fix...

I am able to drive it with the OD turned off...

Really not a happy camper!!! this is the second transmission, and it has about 130K miles on it...

 

FWIW, I did check the voltages...

11.9V after an overnight sit, 13.7V running...

 

11.9 is a bit low, as is 13.7. A fully charged battery should read about 12.6 and the alternator should be putting out 13.8 to 14.4. However, this can be quite different if the regulator is under PCM control.

 

All,
The only battery voltage verses the PCM issue I have first hand knowledge of is once a few years back a friend was telling me no one could figure out why his nissian could not pass emissions testing. I'll use the short version of the story...

Every time he would try to go through the testing the DMV system would tell him that it could not test his system. He went so far as speaking with Nissian directly, I mean no one could figure this thing out and everyone was convinced that his truck's PCM was out to lunch. They could not figure this one out.

Anyhow he found out I use to mess around in mechanics, ( I don't tell very many folks for obvious reasons) so he asked for my help. He told me all of the symptoms and we traded vehicles so I could drive it around for a few days and see what I could find.

Even though everyone had checked the standing battery voltage and the running battery voltage, no one had thought to check the starting voltage. The negative cable was fairly corroded and a little loose, so when he tried to start the vehicle, the system voltage would drop to about 9 - 9.5 volts... enough to reset the PCM. This happened every time he would start the vehicle, so it never would stay in closed loop, once started.

Cleaned up the connections, tightened up the cables, drove the truck around until it reached closed loop operation and presto, everything was working as it should. You could turn off the motor and restart it... and things were fine.

Not that I am that good, just sometimes it is better to be lucky than good!!

Thought this might help.

 

Gentlemen,

Might have bigger fish to fry right now then figuring out the floating miss... I left my expy sitting in the driveway for a few days, while I had some other stuff inside the garage and when I started it, heard some engine knocking until the oil came up to pressure. Dang it. I have duplicated this condition a few times, so now I'm trying to see if this happens if I parked on a flat surface. Sounds like a higher, shallow knock, (located in the heads). Obviously the oil is bleeding down overtime somehow. M/C oil and filter too...

The driveway has a incline on it and the garage is flat...I don't know if that is a player or not... but now I'm off chasing that squirrel!

Besides, maybe low oil pressure is a contributor to this problem too...

Anyhow, just wanted to let you know that I need to chase down this issue, (which I'll probably start a new thread on) so be seeing ya!