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My Ford 2001 F150 4.6L V8 is missing and has never turned on the check-engine light, or produced a code. It has 114,000 miles.It runs ok cold, misses slightly at idle and at almost any speed, although 35-45 seems worse. It’s not bad, it’s just constant. A few times is seemed serious, but then is settled back into annoying.I have an Autozone handheld OBD tool, and it seems to work ok, but the handheld reader has never shown a code, hard or pending. The Check Engine light is off.I’ve replaced the plugs, COPs, and Injectors – the truck still misses. I’ve Cleaned the MAF (with MAF cleaner) and all the filters have been changed regularly.What product would I need to diagnose, or at least be able to read the Ford data?Thanks
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I would say a real-time scanner that can show misses before they throw a code.
On many cars it takes as much as 13,000 to 16,000 misfires to throw a code.
You could also try unpluging the spark plug coils one by one and start the engine and see if you hit one where the miss doesn’t change. If you find that, then swap two coils and see if the miss follows the coil. If it does, change that coil. If the miss still seems to be coming from the same cylinder, you’ll want to repeat the procedure with the fuel injectors, unplug the wire from them one at a time and see if you find one where the miss doesn’t change.
Then I’d check the wires going to the injector while the truck is running with a test light and see if it flashes or not if it isn’t flashing then the injector isn’t getting power. If it does then possibly the injector is bad.
When changing or swapping an injector you might want to pull the fuel pump relay and run the engine till it dies or you might get sprayed with fuel when you pull the injector out.
If you’ve still not solved it checking the compression may be something worth looking into.
Any brand of scanner in particular? A first time buyer can loose one’s shirt!
I was out of town and had to have a mechanic scan and replace a COP, so I replaced all 8 when I returned, about 3 months ago.
The injectors came off for cleaning last week, and I set a stethoscope on them this afternoon, they all sound normal, clicking with a consistent rhythm.
One thing I noted on the injector cleaning, I read that the fuel rails (schrader valve) needed to be depressurized. I was expecting a geyser from what I’d read, but it was a nonevent. Not sure if Fords run high pressure or if it bleeds off after letting it set to cool. It might be starving for fuel, I don’t know. I guess a scanner would tell me that also.
This will help –
http://www.youtube.com/watch?v=9G40e-Ds7dk&feature=relmfu
It easier to watch these few video’s than me going into depth explaining what your possible issues are. Plus it will save my fingers! C8-)
Most misfires under a load are ignition related. I would check the plugs first then start to stress test the coils.
Quoted From dreamer2355:
This will help –
http://www.youtube.com/watch?v=9G40e-Ds7dk&feature=relmfu
It easier to watch these few video’s than me going into depth explaining what your possible issues are. Plus it will save my fingers! C8-)
Most misfires under a load are ignition related. I would check the plugs first then start to stress test the coils.
Duane’s stuff is awesome, I’d also like to add my power balance video as something to check to see if you find a particular cylinder that’s not putting out. Since you’ve done the tune up items already then the next step might be to do a compression and leak down to see if it’s caused by a mechanical issue.
Quoted From dreamer2355:
This will help –
http://www.youtube.com/watch?v=9G40e-Ds7dk&feature=relmfu
It easier to watch these few video’s than me going into depth explaining what your possible issues are. Plus it will save my fingers! C8-)
Most misfires under a load are ignition related. I would check the plugs first then start to stress test the coils.
That vid was my first thought when I read the title of this thread. But since you’ve done the tune up I’d say what ETCG said (though with less detail because I don’t really know what I’m doing). It would be good to identify the cylinder which is missing. This is covered in that vids, just pull each plug and see which one doesn’t make things worse. Then you can rent a compression tester form atozone (or buy one for $45 or so, got mine for Sears) and test that cylinder and compare to others (If you know the problem cylinder you really only need to compare it to one other).
http://www.youtube.com/watch?v=CR32Lpt623M
It is the video where Realfixesrealfast shows how to troubleshoot a no code misfire on a Ford modular V-8. You will probably need a scan tool that can read mode $06 data to have any luck with finding this problem.
Mode 6 is your only hope unless you have a Ford vmm/ids or snapon verus with cylinder contribution testing that was just recently released by ford to the aftermarket I think in 2010.
You just need a generic global scanner to access mode 6 but if anyone has cleared data or KAM then the missfire monitor will not be active until $TID 56 flags a misfire and then utilizing $TID 53 $CIDs 1 – 8 for identification.
Welcome to my world!
If you can graph the o2 data you can find the bank that has the problem but you still have to narrow the cylinder. If you have a laser thermometer you can find the cylinder with that as it should be the exhaust port that has the lowest temp when the mis is happening.
If you have a DSO handy you can look at the kv, coil ramp and burn time and make a diagnostic decision with that.
If you think it is an injector you can do a ramp test and check for pintle activity in the wave form.
You can use the power wire on the coils as they share power and trigger off #1 to see all of them in one picture (works better than mode 6)Or you can just pull wires one at a time wile it’s missing and see which one doesn’t make a diffrence…
This is a video I made on my channel about the one I bought for $20. They also make one that’s a little bit more that is bluetooth enabled that you can link to an Android phone and use the application “torque”. Iphones may have a similar app.
http://www.youtube.com/watch?v=d0ucS4RydkA
Quoted From Neo:
Any brand of scanner in particular? A first time buyer can loose one’s shirt!
I was out of town and had to have a mechanic scan and replace a COP, so I replaced all 8 when I returned, about 3 months ago.
The injectors came off for cleaning last week, and I set a stethoscope on them this afternoon, they all sound normal, clicking with a consistent rhythm.
One thing I noted on the injector cleaning, I read that the fuel rails (schrader valve) needed to be depressurized. I was expecting a geyser from what I’d read, but it was a nonevent. Not sure if Fords run high pressure or if it bleeds off after letting it set to cool. It might be starving for fuel, I don’t know. I guess a scanner would tell me that also.
I cleaned the IAC and checked the TPS sensor with a VOM (the resistance decrements smoothly), and removed the forward portion of the throttle body using carburetor cleaner on the ports and hoses in the rear of the throttle body. I also used the cleaner on the vacuum hoses to see if I could pick up a leak (slick idea by the way).
I did the “power balance test”. The changes are so subtitle on this test I’m not sure I can tell the difference. Injector enable/disable is slightly noticeable, but unplugging the COPs results in a barely perceptible change.
Still missing. Wishing there was a way to better test to COPs.
That will explain why your having a hard time finding the miss.
Do you have any buddies who can help you?
Quoted From dreamer2355:
That will explain why your having a hard time finding the miss.
Do you have any buddies who can help you?
Are we talking just a higher RPM? I can do that.
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