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Bizarre misfire

  #16  
Old 11-04-2018, 06:33 PM
tomkat22
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Originally Posted by pawpaw View Post
Yup it's OBD-2, everything 96 up had to be. Change was begun in 95. Some late 94 & 95 vehicles were OBD-2 & everything had to be OBD-2 in 96 & newer. Does your CEL light up for its self check at KOEO, before you crank the engine?
Yes CEL works fine. I'll post back after I put in new valve stem seals.
 
  #17  
Old 11-08-2018, 08:08 PM
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So I broke down and bought a timing light to check how well spark was getting to the plugs. Light was flashing very fast on Cyl # 3 and #4,passenger side and driver's side,almost a blur. But it flashes much slower on cylinders 1 and 2,both sides. I'm guessing that's not normal.? Maybe a failing coil(s)?
 
  #18  
Old 11-09-2018, 01:10 AM
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What does the CReader misfire monitor show for the different cylinders?
It's OBD-2 data stream seems to be able to check each cylinders misfire, so should be able to help narrow down where to begin to look for gremlins.

After reviewing your posts & seeing as how you said earlier that you had signs of melted wiring in a engine wiring harness, I'd be looking in there first to see if something is amiss & the scan tool can help with where to begin looking for wiring problems to & from things like the coil packs.

You ask about not being sure about this vehicle being OBD-2 & if you enter the make year & model vehicle, then scroll the reader menu, it'll tell you what OBD system you have & what it can monitor for you. So make good use of the info it can provide in narrowing down where to focus your trouble shoot.

From the info you've posted so far, it sound like you probably have more than one problem.
We are to begin with the lowest number trouble code, put it right & work our way up the list.

More thoughts for consideration, let us know what you find.
 
  #19  
Old 11-09-2018, 01:10 PM
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Creader scantool only gives 17 reports/items,IAC temp,TP load,STFT,LTFT,etc.I wish it would give misfire counts for each cylinder but it does not. It does on my 07 Kia Rio,it gives 39 "reports". Ranger is JW1850 protocol,Kia is ISO9141. Yeah wiring was in bad shape but I got that sorted out.Found a nick in the wire going to the CKP,was shorting to ground and shutting down the engine. If my math is correct a spark plug should fire 15 times per second at 900 RPMs(on a waste spark system,half that on non-waste spark system). Half my plugs/cylinders seem to be firing that fast but some are firing much slower,maybe 4 times per second. I have a new coil on order,hopefully that will help.
 
  #20  
Old 11-09-2018, 01:29 PM
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Pull the suspect coil & have your favorite auto parts store perform a no cost bench test on it to confirm if it has problems. Is the suspect coil the one you may have electrically over stressed by removing both plug wires & watching it arc?

Seeing as how you seem to like doing your own diagnostics & wrench turning, maybe consider coming by the inexpensive ELM scan tool & running FORScan diagnostic freeware that's tweaked for Fords, on the viewing device of your choice, as discussed in this thread. https://www.ford-trucks.com/forums/1...-scantool.html
This combination is able to perform in depth diagnosis, including accessing the system misfire monitor, so can likely offer up helpful clues on which cylinder/s are troubled.
 
  #21  
Old 11-11-2018, 12:46 AM
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So the 2 coilpacks on a '97 fire at the exact time and sequence correct? Seems to be conflicting information on that.I don't see how the rear coilpack can do anything other than mirror the front coilpack, lockstep in unison? Supposedly you can unplug the rear coilpack and the engine will still run fine.(haven't tried it).
 
  #22  
Old 11-11-2018, 03:52 AM
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Have you reviewed the trouble shooting steps in the post #9 link? This dual coil pack system uses a dual output crank sensor for the computer to use in controlling the ICM to determine when it commands two coil packs to come on line & begin to fire all of the spark plugs.
When you crank the engine for a start, only one coil pack is used to start the engine. So only half of the plugs get a spark when you crank the engine for a start.
After the engine is running, the computer commands the ICM to activate the other coil pack, so now all of the plugs should be firing.
This is a waste spark ignition system with two coil pack & 8 spark plugs (each cylinder on this 4banger engine has Two spark plugs.) The coil packs have the cylinders they're firing paired together such that when one cylinder is firing on its Power stroke, its companion cylinder is firing on its Exhaust stroke (waste spark). On the next revolution of the crank shaft the waste spark cylinder is firing on its Power stroke & its companion cylinder is firing on its exhaust stroke. SO, in this waste spark system the spark plugs, wires & coil packs are worked Twice as often as the old distributor, or COP ignition system. Thus we need plugs, wires & coil packs that are designed to take the Double work load & hold up & Motorcraft parts are recommended as they've proven to be of good design & lasting quality.

So, to have all this work properly the Dual output crank sensor, ICM = Ignition Control Module & Computer have to work together. If any of those components, or the wiring to & from them is corrupt, the system will act out & when it does a good scan tool & diagnostic software will usually be able to determine if there is a problem & detect pending, or set trouble code clues, or be able to read & display sensor PID's to see if they're abnormal, or corrupt & that can help focus a trouble shoot.

SO, between the trouble shooting link, your recently acquired timing light, a multimeter, or 12 volt test light & a good scan tool running a good diagnostic software to your viewing device, you should be able to unravel any system mischief. Right now you've not posted up any trouble codes that says the computer is unhappy with how the ignition system is behaving, just that your not sure what your timing light flashes are indicating. Also we're not clear just how sophisticated the CReader abilities are, so I'm not sure if it's providing a proper, or complete look at your vehicles OBD system that we know the ELM & FORScan is capable of.

SO, right now, if you suspect a ignition system problem, that seems to leave you with reading the link in post 9 & stepping through his trouble shooting of the dual output CKP sensor, ICM & Coil Packs, or removing each for a bench test if your favorite auto parts store can do that. Most can test coil packs & some can do the ICM & you can do the CKP sensor with a multimeter. You could also swap coil packs to see if it runs better or worse & maybe get an idea if one has a problem.

Make sure you have the plug wires connected properly & that the melted wiring is put right. The lead that was shorting to ground might have damaged what ever was feeding it power, so have a look at its wire color code & determine where that wire came from & where it was going. Solid state things don't like voltage surges & excessive loads that a short circuit causes, so that problem may have caused other woes.
Did your current situation come about after the melted shorted out wiring arose?
What caused the wiring to get hot & melt? Did your current woes come about after that? Just trying to get a historical idea of when & how things happened to try & understand whats happening now & if their inter-related.
 
  #23  
Old 11-11-2018, 02:08 PM
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Occasionally a P0171 will pop up but I'm sure that's from a lean condition caused by one cylinder misfiring. At this point I'm just trying to find out WHICH cylinder is misfiring. I'm pretty sure it is a combination of oil fouling and a weak or no-spark on that cylinder. It would help to know what both those coilpacks are doing at any given moment. I understand the waste spark system,thats a different discussion.That can happen with 1 coilpack or multiple ones. I've noticed the plugs on the exhaust side of the head seem to foul much more than the ones on the intake side. I assume because of their position in the ceiling of the cylinder?
 
  #24  
Old 11-11-2018, 04:41 PM
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Lets think about this some more.
Seeing as how the felt miss condition seems to come & go, along with the lean trouble code & lean fuel trim numbers on your scan tool & a Spark misfiring cylinder wouldn't cause a Lean condition, it would cause a Rich condition as the fuel squirted by the fuel injector didn't get burned. It would get dumped down stream past the upstream O2 sensor & then into the cat converter for processing.
SO, since you don't have a Rich trouble code, or a Rich fuel trim indication, its not likely a Spark caused misfire, instead look to a dirty/acting out Lean Squirting fuel injector.
With the engine at idle, use your mechanics stethoscope, or rig one from a length of tubing, wooden dowel rod, long screwdriver, or the like, one end on the injector, the other to your ear & have a listen to each fuel injector, to determine if one sounds different than the others. If so, remove, inspect & clean that puppy & let us know how it goes.
EDIT: Inspect the injectors electrical wiring & electrical connector casing for damage, cracks, its electrical contacts for corrosion, bent pins, spread open sockets & that it was properly fastened/locked into place.
 
  #25  
Old 11-11-2018, 04:55 PM
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I have a mechanics stethoscope and all fuel injectors are clicking fine.They are all new,cheap ones from ebay but still I don't think that is my problem. One cylinder not contributing would create a lean condition regardless no? I'm almost certain it is oil fouling snuffing out the spark,some of the plugs look pretty grim. I've bought 4 of those non-foulers,gonna put them on there as an experiment.I hate those things because they not only protect the plug from the OIL but also from the spark! LOL
 
  #26  
Old 11-11-2018, 05:08 PM
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Seeing as how the condition is intermittent, have you listened to the injectors long enough for the miss to occur While you were listening?
Was the miss occurring Before you replaced the injectors?

If the miss is being caused by a fuel injector intermittently giving a Lean squirt, or a no fuel squirt, the O2 sensor would report a lean condition, because there would be too much air/oxygen in the exhaust passing the O2 sensor after that lean squirt fuel delivery caused misfire.
 
  #27  
Old 11-11-2018, 07:29 PM
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Piddled with it some more today.Think I might have found the problem,unfortunately. Did a wet and dry compression test on all cylinders while engine was COLD. Only got about 60 psi on all cylinders but 90 to 110 when wet tested with oil. Gonna do the same test tomorrow when engine is hot.(got dark). When all the metal gets hot I suspect compression will go up. Sounds like the rings might be in bad shape. BTW,I unplugged the coilpack on front and back coilpacks and it started up and ran both times.Wierd. Although it seemed a little rougher when the front one is unplugged.
 
  #28  
Old Yesterday, 07:31 PM
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Nope.Compression gauge was malfunctioning.I had been having issues with its Schrader valve.Rented one from Autozone,showed exactly 150psi on all 4 cylinders. Also discovered #4 post on rear coilpack has zero spark coming from it. And #1 and #2 on both coilpacks are "spotty". New coil arriving tomorrow.The search continues...
 


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