Rough Idle & Misfire No Codes - 2007 Ford F150 STX 4.2L 285k miles

Hi Guys,

I'm new in this thread, so this is my first post on how to diagnose a problem. I'm working on my neighbor's 2007 Ford F150 STX 4.2L 6 cyl, with about 285k miles. Can't figure it out b/c I'm kind'a new to this stuff and am learning-as-I-go. The biggest challenge is sorting through all the PIDS and procedures using a DVM and scope. So your help is much appreciated.

The guy's truck is idles rough and has an apparent misfire all the time. It has plenty of power. Sometimes it stalls when he stops at a light. There are no related DTCs. Mode 6 shows 'all OK'. DTC check came from an OEM Hickok NGS scanner, and the Mode 6 and Live Data came from an OTC Pegisys (combo scanner & scope). All onboard tests were done with both scanners.

My biggest problem is not knowing what I'm looking at with live data, so don't know where to go next.

I got Paul's book and tried using it, but it's not vehicle specific, so not sure what data transfers to this vehicle. Anyways, I did a bunch of tests based on the OEM manual (the engineer's procedures that lead you around by the nose without using any common sense!), but everything I tested checked out OK. Mostly I checked voltages and got some wave forms at the PCM back-probing the connector. Each wire off the coil (non-cop) has a near identical signal, but it's hard to read b/c of the poor resolution on this scope. The guy changed the plugs and wires about 4 years ago to fix this rough running and it helped a bit. I pulled each wire off the coil and had the ground shunt to see how fat and strong the spark was and it was blue to white, fat, thick and jumped a LONG WAY (scary!). Every time the wire was unplugged the RPM's dropped about the same. All injectors have the same wave form (nearly identical), but I could only check them 2 at a time b/c my scope is only 2 channel and there's 1 PCM wire for each Injector). The CKP and CMP have what look like good wave forms, fuel pump amps look good on the DVM (btw 4.5-5A/idle-2500RPM). MAF has good voltage. Disconnecting the Evap Purge Solenoide hose from the intake manifold (and plugging them) didn't made any difference. Removed and inspected the EGR valve to see if it had carbon caked on the pintle (like in the old days) and it was pretty clean and didn't look bad. Didn't do any EGR Valve off-truck tests (with volts, amps and frequency generator), but did do the actuator tests KOER, and when the valve opened up the engine ran worse. Actually I did about 20 different tests using the Pegisys and the 2 that made a difference were: 1. when the Duty Cycle of the fuel pump increased, the engine ran a bit better, and 2. changed the fuel filter, since the guy hadn't changed it in EIGHT YEARS (yup, that's right, E I G H T Y E A R S !). The dark gas that ran out the back (gas tank end) end was BAD, and the gas that ran out the front was also a bit iffy. So I immediately figured the Injectors may be plugged. I changed the fuel filter BEFORE doing all the above tests, and the Injector wave forms were the first that I did.

The guy told me it ran rough since he bought it used (with around 130k miles), and so he changed gas type from Regular to Shell Premium, which made it run better (quit stalling all the time).

Oh yeah, I did a smoke test on it and found no vacuum leaks (only about 1 psi). Did the amp draw Cylinder Compression Cranking test (with the Pegisys) and they were all within about 5% of each other. I wiggled nearly all the wires and connectors, checked a few of the main grounds in the engine compartment and didn't find anything of note.

Haven't yet tested the Knock Sensor, the Throttle Body or the Accelerator Pot. One thing I noticed is, when the accelerator pedal is very slightly pressed, it runs even worse. That tells me it may be a bad Pot, but not sure. Ran out of time to test that.

I have a 2003 Sport Track and had to change the Intake Manifold seals b/c they got 'hard' and a couple cracked at around 120k miles (@ around 15 years old). Some YouTube videos say the same thing fixed their 4.2L. But the reason I discounted that possibility is b/c I didn't see any smoke coming out where they connect to the head, but when I did the Sport Track, smoke billowed out 2 places. So not sure if the seals are a problem, but my guess is YES b/c they're so old. Maybe there's another test to verify the Intake seals are leaking? I don't want to use PROPANE due to the Flammable Danger involved, unless there's a way to do it that won't be 'scary!

One thing that goes bad with these engines is the Intake Runner bushings. They crack and break off which causes the runner butterflies to flutter, which causes runnability problems. But when I did that test using the Pegisys, it seemed to be OK.

Next time he drops it off, I'm going to crawl underneath and follow all the lines and wires from the engine compartment all the way along the body to the rear end end and above the spare tire to see if there's any damage (from mice or rats), or if I can see any other things out of place.

Otherwise, at this point, I'm 'lost in the woods'. I have no idea what may be causing this. My first thought when changing the fuel filter was, Clogged Injectors. But they show up good on the scope. They ALL have nearly exactly the same wave form.

Oh yeah, I scoped the CKP & CMP, and the CKP & KV#1. But not sure how to read it. They were consistent, except with the CKP & CMP the CMP signal kept swapping rhythmically, and not sure if that's supposed to happen (Cam waveform consistently jumped to the left and then to the right of the Crank start point).

One more thing I didn't do was check all the fuel rail pressure with a gauge, b/c there's nowhere to connect to it (at least not that I could see). The NGS scanner says the KOER & KOEO psi are good. So I discounted that. Same with the fuel rail pressure sensor, b/c it had good voltage according to the book test. Is it possible that the injectors are not quite clogged but still restricted enough to cause this rough running? So when the Fuel Pump Duty Cycle increased it pushed more VOLUME of fuel through them to make it run better? Or maybe it also has a vacuum leak?

Biggest problem is, Ford, in their INFINITE WISDOM, made an intake manifold system that requires you to REMOVE the damned thing to get at the Injectors. You can't get to the Runner Control either, b/c it's BURIED in the back underneath the Intake Manifold. Gotta luv these engine designers!

Incidentally, I have Wave Forms and Live Data if you want to see it, but not sure what to show.

Any help is greatly appreciated!

cadman777 wrote: My biggest problem is not knowing what I'm looking at with live data, so don't know where to go next.

I would start with Fuel Trim. Is it Positive, negative, equal bank-to-bank...? What kind of activity do you have on your Oxygen sensors?

My first thought when changing the fuel filter was, Clogged Injectors. But they show up good on the scope. They ALL have nearly exactly the same wave form.

You, likely, won't see a clogged injector through injector waveforms. The mechanical movement may be present, but there might not be sufficient flow. To determine if an injector is clogged, do an injector balance test. Watch for the fuel pressure to drop, equally, for all injectors.

the CKP & CMP the CMP signal kept swapping rhythmically, and not sure if that's supposed to happen (Cam waveform consistently jumped to the left and then to the right of the Crank start point).

Is this at idle? Unless there is VVT actuation, Cam/Crank correlation should not change. I'd like to see the waveform.

Here is a link to a similar case study on a Ford with misfires and no codes.
www.scannerdanner.com/forum/lab-scope-di...-cylinder.html#41575

Chad,

Thanx for your detailed reply (including that excellent Tutorial link! I'm still foggy on reading the 'ramped' wave forms. Your overlay chart is superb!).

Answers:

O2S1 B1 & B2 both swithing btw .1-.72 according to spec
O2S2 B1 & B2 Sensors holding around .72
WOT & return to idle seems to be good too w/the correct delays and return to normal switching

STFT & LTFT: I recorded it, but for some reason it's not showing up in my 'Playback' list. Bummer! That means I gotta do it again. But Ineed to do the other 2 tests too: Tail Pipe Pressure and Frequency. If memory serves, both of the LTFTs were around -7, and both of the the STFTs were around +4.

From what Paul says in his book, I figured they're OK, b/c they're w/i the +/- 20 that Ford requires, but other than that, I have no idea except that one is lean and the other is rich. But then what else do I need to look at in combination to make sense out of these?

Was wondering about that w/the Injectors. Didn't know if I could tell if they were 'squirting' enough volume or what the pattern is. There's ONLY ONE Injector accessible to get a spray pattern and do a true volume test. To get to the others, you gotta remove the Intake Manifold! But I don't know if I can get that one off w/o first removing he fuel rail which means off comes the manifold, which ain't gonna happen until I figure out what's wrong w/this thing. So your suggestion of doing the PRESSURE DROP test. That's gonna be my next test.

There is no VVT on this engine, so that's eliminated.

I can't figure out how to get the Frequency on my scope like you show in your BLACK wave form? Any ideas?

Here's some pics of some the WaveForms I got:

Typical Injector:


CKP & CMP


CKP & CMP


CKP & CMP


CKP & KV#1


CMP & KV#1

cadman777 wrote: They were consistent, except with the CKP & CMP the CMP signal kept swapping rhythmically, and not sure if that's supposed to happen (Cam waveform consistently jumped to the left and then to the right of the Crank start point).

That's because the crank rotates twice as fast as the cam. CMP will repeat every two CKP syncs not every one.

one is lean and the other is rich

When I see this, the first two things that come to mind is:

1) A misfire can make an O2 sensor read lean, due to the un-burned Oxygen entering the exhaust. The misfire will, likely, be on the LEAN bank.
2) A restricted exhaust will be rich on the bank that is restricted.

However, neither one of those scenarios would be represented by fuel trims of

both of the LTFTs were around -7, and both of the the STFTs were around +4.

I can't figure out how to get the Frequency on my scope like you show in your BLACK wave form? Any ideas?

I am not familiar with that scope. Not all scopes have the frequency function.

OK, thanx, that makes sense.

I contacted OTC to see if they can tell me what settings I need to make on this Scope.
Meanwhile I need to know how to hook up the Scope to get the Hz signal.
Is it the same as when you take CKP voltage?

cadman777 wrote: I need to know how to hook up the Scope to get the Hz signal.
Is it the same as when you take CKP voltage?

The Frequency (Hz) trace is a processed output. There is no "hook up". It is calculated from the Crank signal. You connect your labscope to capture the Crank signal. Then, the labscope software "looks at" the crank signal, calculates the frequency, and plots it as the Hz trace.

OK, I get how you identify each cylinder on the Black trace.
But not sure how you identify each cylinder on the Blue trace.
Is it 140° past #1 (kV) marker on the 1-3-2-6-5-4-8 firing order?
Or is it something else?
Would you please post a link on how to read the Blue trace by firing order?
Thanx!

Check this thread out. If you, still, have questions, I'll be happy to answer them.

www.scannerdanner.com/forum/diagnostic-t...35-piston-chart.html

OK, I get it now.
The idea that the exhaust waveform is for EXHAUST ONLY just didn't sink-into my thick skull.
So making these overlays is not big deal for me.
But do you do all this in Paint?
Or do you use another software?
Doesn't that mean you first have to save your waveform from Pico software (or whatever) to disk first?
If you save the image from Pico software, what file format do you save it in?
GIF, so you can make the background translucent?
Or do you just do a screen shot and then save it as GIF?
Just curious is all.
Probably save me all the R&D trying this and that and the other method...

cadman777 wrote: But do you do all this in Paint? Or do you use another software?
Doesn't that mean you first have to save your waveform from Pico software (or whatever) to disk first?

I use windows "Snipping Tool" to create a screenshot of the waveform. Then, I use a free program (for Windows 10) to manipulate and annotate the screenshot.

Yeah, I just found it before you posted this.
But I'm not on Win10.
Costs too much to buy all new software.
What a racket!
Anyways, do you know of anything that'll work on Win7Pro64?
I can't find anything... been looking for 2 hours online!

cadman777 wrote: Yeah, I just found it before you posted this.
But I'm not on Win10.
Costs too much to buy all new software.
What a racket!
Anyways, do you know of anything that'll work on Win7Pro64?
I can't find anything... been looking for 2 hours online!

Win 7 should have the snipping tool. Or you could go old school and use Alt+PrintScreen to grab the active window. Your 'scope software might also have a way to save images built in. Pico and Hantek do.

support.microsoft.com/en-us/windows/use-...5f-f220-97299b865f6b

Also last I knew you could still upgrade 7 Pro to 10 Pro for free. Just be sure to make a note of your license key before you start.

www.cnet.com/how-to/how-to-download-wind...t-windows-7-is-dead/

Yeah, I'm pretty savvy on all that stuff.
It's just, now that I know there's a perfect tool for this job, it PAINS me to have to do it the long hard way!
I just contacted the guy who wrote the program, and he told me he would port it over to Win7 IF he had time.
But doesn't look like it's gonna happen any time soon.
I can't downgrade to Win10 due to application replacement costs.

Gotcha. Wonder if you could run a Win 10 VM on a Win 7 host.........

Or this will probably run on 7 since it's older software that's been re-released. Best to email them to check before buying.

driveabilityguys.com/software-and-tools

Sounds good.
That was the first one I checked out, but decided it was too expensive to keep buying overlays.
However, I'll contact the guys and inquire, since my options now are limited by Bill Gates' (dr. death's) planned obsolescence scheme.
Cheers!

Update: I tried contacting 'The Drivability Guys' but couldn't find an email address on their web site. That's a bad sign. I just want to make an inquiry as to what their overlay consists of and what it can do and how to use it.

cadman777 wrote: That was the first one I checked out, but decided it was too expensive to keep buying overlays.

As for the piston charts, although the free Windows 10 program has a piston chart too, I prefer the one that the Driveability Guys offer. It is a one-time purchase. Then, you can create as many overlays as you want. Well, worth the cost, in my opinion. The free Windows 10 chart is reversed, in comparison. You must read it from the bottom, up. Rather than from the top, down. However, the free Windows 10 software has many more features that The Driveablity Guys' does not have. I use them both.

cadman777 wrote: However, I'll contact the guys and inquire, since my options now are limited by Bill Gates' (dr. death's) planned obsolescence scheme.

Don't get me started on microsoft or their founder :evil: That said obsolescence is what it is. And they're not deliberately obsoleting PC hardware like they were back in the day.

VMs are an easy solution for running older software unless you need to connect them to physical hardware. I'm not having any luck trying to get an android VM to connect to bluetooth. So if you need physical connectivity it may make sense to just get another laptop. Used business class laptops can be had dirt cheap on ebay. I've got less than a hundred in the one I'm using to post this.

cadman777 wrote: Update: I tried contacting 'The Drivability Guys' but couldn't find an email address on their web site. That's a bad sign. I just want to make an inquiry as to what their overlay consists of and what it can do and how to use it.

Click one of the Fliers at the bottom of their downloads page

Can you send me their features and instructions on it?
I want to see what all it IS.
I'm still unclear how it works and what all its features are.
Thanx...

I'm back on this truck again.
Made a differential pressure sensor from a piezo disk taken out of an old CO sensor.
Worked like a charm!I scoped the Exhaust pressure and the Intake vacuum (disconnected the hose going to the break booster).
See scope screens below.
At this point I'm beside myself as to what makes this truck run rough.
It really doesn't feel like a misfire, but it does feel like the crank is imbalanced.
If anybody knows what I'm talking about, I'd appreciate any more ideas on how to diagnose this thing.

What I REALLY want is to get a Rotkee or USB Scope and get all the scope signals that are needed to check all the timing and other vitals on this engine.Is that even a real thing I can do?

Also wondering if I can use the scope to test for a broken crank or some other kind of physical damage, such as a stretched timing chain or something like that?

TIA...Chris

Exhaust


Vacuum


Overlay

Sorry for the mess.
It's all I had to work with.
(Yes, after all my whining, I finally sucked it up and put together a Win10 SSD for my laptop...)