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Discussion Starter · #1 ·
Hi folks
Sorry for not being here for a while, just live in the way.trying to get back in the game.
I need some help , miss fire cylinder number 3,I got that.I did pretty much everything from spark plugs, wire,coil, injectors,filters, complete new exhaust with O2 sensor front and back.
Most parts are OEM no ebay stuff and I still can't get rid of the miss fire.
The spark plugs look all fine except number 3 which is fuel fouled I take it, but I don't understand why because all injectors are new.
Is there something else I can check ?? Somebody has an idea?? Any suggestion will be appreciated!!

Thanks allot guys
 

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Discussion Starter · #3 ·
Hello 👋
Well I follow a Ford mechanic on YouTube he showed a wild situation with a melted intake manifold so I did the spray down with starting fluid no change.what is also weird is that under load seems to be better than idle or low throttle input, CEL is flashing when it's running better. I'm looking for a pointer to test a specific part which I don't know what that is , that's why I'm here asking.
Thx anyway 🙂
 

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97 Thunderbird 4.6, 98 Mark VIII LSC
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What year is it? The 94-95 PCMs are known to hang injectors open, which is consistent with what you're describing. Not impossible on a 96-97 but much less common.
 

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Discussion Starter · #5 ·
Hello 👋
It's a 97 .
What do you mean by that ? you saying that the injectors a pouring fuel in all the time??
I tried something today I pulled the plug on the injectors
One at the time seems to make no difference I had 2 3 and 4 of still ran didn't seem to care
 

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1995 Thunderbird LX 4.6 red
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You could still have a bad injector. Try switching the number 3 injector with number two and see if the miss moves. IF it moves, swap out the one injector. If number three stays the problem check the computer or the wiring harness.
 

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Discussion Starter · #7 ·
Hello 👋
I moved the injectors around before I changed them out but no changes . what baffles me is no changes if you unplug the injector either.
Today I go and get a noid tester set to see if the plug is actually pulsing as it should.i also have a injector tester on order.
Is there anything else on the hard part side what would cause the miss fire??? Like leaking intake valve or something in that regard ??
Thx
 

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That's the symptom of a stuck injector, not eec. if it sticks, pulling the plug wont change anything.
try a solenoid light, and also see if the plug is trying to fire.(I use an old school timing light that uses the spark to trigger the flash.)
 

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Discussion Starter · #9 ·
Hello 👋
I got myself a noid light tester which shows the plug fires that's the good news .the bad news the tester what pulses the injectors ruled the injector okay . I went ahead and changed the injectors again from a different vendor and set but still no changes on the miss fire.
On the weekend I will take the valve cover off to see if the follower is bad or the lash adjuster that is all I didn't do yet.
Any other ideas what to look for???

Thx
 

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97 Thunderbird 4.6, 98 Mark VIII LSC
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Is the injector pulsing? It's hard to understand if that was a test you did; I see you tested for spark. What does the plug look like if you take it out and examine the tip?
 

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Discussion Starter · #11 ·
Hello 👋
The plug is fuel fouled like incomplete combustion.
The tester I have pulses the injector,if you do that the car runs funny because the pulse is not the same sequence as the rest .
Besides the car runs like on 7 cylinders, it runs okay under load or higher Rpm but goes back to the run like 7 cylinders after letting of the gas or low engine speed with low throttle input.
Under load CEL is flashing but running better and constant on if run like ****.
Remedy right now is driving without overdrive in the city to keep the rpms up
I tested the injectors with the pulse outside the car too with the cleaning adapter to see the spray pattern, looks normal.
To me looking like valve issue not opening far enough or leaking with blow by, can't think of anything else.
 

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If it runs better at higher rpm, I'd suspect a broken ring or stuffed valve.
An engine can run with no rings, if you keep the r's up.
(I finished a race in the 70's on a dirt bike that had broken the rings and spit them out the exhaust port.)
 

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97 Thunderbird 4.6, 98 Mark VIII LSC
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You could try doing a compression test to see how #3 compares against the others.

I don't think I clearly understand still... is the injector pulsing and delivering fuel while it's connected and on the car? It's clear to me from your earlier tests that the injector itself is working but I was hoping to ascertain if the injector is pulsing and delivering fuel when it's connected on the car (e.g. to rule out a PCM or wiring issue). Based on your plug observation (wet with fuel?) it seems that it is, but again - I want to be sure my understanding is correct.
 

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Injectors can function, but not work; Some of the 19lb stockers I used to see if my cleaning setup would work, but fuel didn't spray, it dripped off the tip.
I never recovered those, although to be truthful, I didn't really try. If they'd been 39lb ers, they would have got more attention.
 

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Discussion Starter · #15 ·
Hello 👋
I tested the injectors both ways in and out of the car
Spray pattern seems normal,as I can hook up a can of brake parts cleaner to see if the injector is okay.
Next weekend I will be able to take the valve cover off to see if there is anything suspicious and trying to perform a compression test
 
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