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I appreciate all your time and thoughtful input. Electrical theory isn’t natural for me but I can struggle through.
You said call you out when you talk crap. I have to catch you first, LOL.
I was measuring across the + and - posts of the coil. I’ll retest with the - post of the MM on the battery ground.
All vacuum readings were rock steady. Virtually no needle movement.
I’m still running ported vacuum during testing so there is no increase in idle speed when it’s connected until throttle is cracked. I haven’t tried manifold vacuum for a while. I’ll experiment with that.
Here are a couple of pics of the dizzy/coil if for no other reason than to see if anyone spots something I’ve become blind to.
6 by 8, in your last post you wrote “You've always mentioned a backfire, but now you mention popping at the exhaust, which I would classify as a misfire.”.
I’m becoming more sensitive to various nuances. With vac adv disconnected there isn’t evidence of a misfire (“stumble”), only the pops (backfires) in the exhaust. The best way I can describe the sound is like a heavy book that is dropped flat to the concrete floor; a sharp report. This continues intermittently unless throttled up or down out of the trouble zone. When vac adv (ported) is connected the same thing happens except there is a perceptible “stumble” that gradually comes on starting at approximately 1600 RPM preceding the backfires. At this point the engine is running rough and I haven’t pushed it further. This is where I “thought” I saw erratic timing light behavior a couple days ago but couldn’t replicate it yesterday.
Maybe I’ll see what I can do about posting a video if the issue is still there after my next stint.
If I was in the TV show 'Who wants to be a millionaire', and the question for a million $$'s was, ''Are those HT leads 1 month old, or 12 years old?'', I'd be going home a LOSER, and no doubt would sulk and cry for at least a month. LOL
Wow ! They're clean !
I had seen them in your earlier photo and assumed they were new/newish.
The rock steady needle is an excellent sign, as is the high 17.5'' vacuum. I assume that was observed with no vac adv.
I'm not sure what to expect when ported, and then manifold, is attached, but I'm curious, and you never know, it might tell us something useful, especially as in theory no extra advance is applied when connected to ported, and yet you observe rough running with ported.
(The total vacuum reading and rpms should increase with manifold attached)
Your dizzy looks like the Motorcraft dizzy that came with my truck. Yuk ! I don't like either of 'em.
I'm not familiar with the DS dizzy, but I'll mention 2 things that may or may not be applicable to the DS.
In the Motorcraft, the electronic box that the red/black wires attach to, had to be a certain gap from the center where the rotor fits on to, and there was a +/- 1.5'' ground wire.
I can't remember if the ground wire was above the plate, or under the plate, the plate being the round thing just under the vac adv arm.
Which reminds me, in the photo of your ignition module, it looks like it is hanging loose. Is it loose, or is it solidly attached to something like the inner fender ?
Ok, hopefully the ohms and voltage tests mentioned earlier will reveal something when you get to it.
You taught me something today, thank you.
Over the years I have seen ''dial back'' timing lights mentioned many times, but for some reason, I've never ever looked up what that meant.
Seeing the rpms at the same time as the ignition timing is incredibly useful.
I need to sidetrack for a minute and have a rant about Covid vaccinations.
For anyone about to have their 1st or 2nd vaccination, or a booster shot, don't ask, but insist, that the needle is ''aspirated'' BEFORE the crap is injected into the arm.
If the nurse, trainee tea lady, Doctor, or whoever has been employed to provide the injection, refuses to aspirate, walk away immediately. (And yeah, remove the needle first. LOL)
Why ????
The vaccine must enter a muscle. Period.
If it enters a vein, that's when serious complications can occur, and I can see that many reported 'side effects' are possibly from an injection into a vein.
A tell tale sign of a vein injection is a 'funny' taste in the mouth soon after the injection. (Of course it's too late then !)
I'm annoyed at how many friends and family members are telling me that the person injecting them did not know what aspiration meant.
(At least they didn't mind aspirating once it was explained to them. )
Also, google the daily intake guidelines for zinc and vitamin D, then decide if yours is high enough to assist the immune system.
Up until now we thought that there was only a problem with backfiring at certain rpms, and then amplified with the addition of vacuum advance.
The pops in the exhaust, at idle, with or without vac adv connected, suggests it's a misfire, which suggests it's an HT lead issue. (And yes, I could be wrong.)
I think(hope) your next stint will be very revealing.
To be clear there is not any stumble/misfire/backfire with vac adv connected at idle. It begins at about 1600 RPM in that scenario.
From that post: “When vac adv (ported) is connected the same thing happens except there is a perceptible “stumble” that gradually comes on starting at approximately 1600 RPM preceding the backfires.”
I did a resistance test on all HT leads including coil. A couple of notable conditions were discovered. All the plug leads were good at around 500 Ohms/foot which is spec. However the coil lead is zero and it won’t measure continuity. Dose that make sense, and the engine runs? Every distributor contact end is pretty heavily oxidized and corroded. Except #8… I found the contact inside the boot was pointing horizontal at the back end of the boot, and not pointed downward to snap into the dizzy. And that contact is clean and uncorroded. I have no idea how I did that back in 2008. Or how I’ve not noticed it until
now while changing caps. I’ve attached some pics.
In any event I am cautiously optimistic for positive results after I install the new Accel wire set that’s supposed to arrive at my local auto parts store late this afternoon.
BTW, the ignition module is secured in its factory position.
#1 - 7, typical #8 #7 and #8 for comparison Coil lead, O resistance
The number 8 HT lead may have in fact been fitted correctly originally in 2008, but only when removing it to work on the dizzy recently did the end clip slide back into the boot.
I think that lead could be the cause of the misfiring, a.k.a. popping.
The coil HT lead could also have been the cause of the popping.
That said, the number 8 plug tip might have had connection with the clip.
If it did, it may have caused the misfire at higher rpms.
The coil HT lead, with zero ohms and zero continuity whilst sitting disconnected on the table, would have had some continuity with the engine running, but at higher rpms, with more power passing through it, simply got overloaded and caused the backfiring.
I don't think the corrosion was the issue, but it's certainly not something that one wants to see.
I still have no idea exactly why the issue was only in a 300rpm range, but seeing as you are on the verge of fixing the issue, I really don't care, and I'm sure you don't either. LOL
You can ignore the vacuum tests mentioned before.
However, connect the vac adv to manifold when the issue has been fixed, adjust down the rpms, and observe the higher steady vacuum reading at 850rpms. No need to return to ported.
Test the coil voltage and ohms too, as per the earlier post.
The number 8 HT lead may have in fact been fitted correctly originally in 2008, but only when removing it to work on the dizzy recently did the end clip slide back into the boot.
I think that lead could be the cause of the misfiring, a.k.a. popping.
The coil HT lead could also have been the cause of the popping.
That said, the number 8 plug tip might have had connection with the clip.
If it did, it may have caused the misfire at higher rpms.
The coil HT lead, with zero ohms and zero continuity whilst sitting disconnected on the table, would have had some continuity with the engine running, but at higher rpms, with more power passing through it, simply got overloaded and caused the backfiring.
I don't think the corrosion was the issue, but it's certainly not something that one wants to see.
I still have no idea exactly why the issue was only in a 300rpm range, but seeing as you are on the verge of fixing the issue, I really don't care, and I'm sure you don't either. LOL
You can ignore the vacuum tests mentioned before.
However, connect the vac adv to manifold when the issue has been fixed, adjust down the rpms, and observe the higher steady vacuum reading at 850rpms. No need to return to ported.
Test the coil voltage and ohms too, as per the earlier post.
Thanks for the tips on dielectric grease. I’ve been using it wrong for years apparently. Also thanks for the Covid vaccination info. I didn’t know that either.
And apparently I don’t know much about anything, or have a black cloud and /or bad juju hanging over me. I replaced all the HT leads including coil. Checked coil resistance values and found them within range according to the Ford Service Manual. Runs worse than ever, misfires so bad it will hardly idle, and then not for long without throttle action. Seeing extremely low almost non existent voltage (.04-.15V) at the coil when running with MM + on the coil + and MM - on the battery negative post. Erratic timing light behavior, similar as seen before but highly amplified. Simply unbelievable. I’ll be back with more after I process everything I did and saw this morning. I need to do some research on the ignition circuit to understand some things.
EDIT: ignore the entire second paragraph of this post. Rantings of a madman. More tomorrow.
LOL @ rantings of a madman and bad juju hanging over you.
It's very easy to feel disheartened, but back up a bit, and you'll read that you were the one that said something like, ''I did this, this, and this, and I therefore think it is an electrical issue, not a fuel issue.''
Then you said something like, '' I did this, this, and this, and I now believe it to be an HT lead issue''.
Nothing wrong with your understanding and logic, and given that it's your first time working with this type of issue, here's another one of these :
Three things come to mind.
Was the firing order inadvertently changed ?
Were the end clips on the HT leads fitted correctly, without damaging the thin center bit that sticks out of the leads ?
Is the 'new' coil fault free ?
If the firing order is still correct, I'd say refit the old 1 to 7 HT leads and coil, only fit the new coil HT lead and number 8 HT lead, and observe. Then start fitting the new bits, one at a time.
What was the voltage reading on the old coil ? (Yeah, .04 to .15v isn't right)
Was the MM set to DCV when reading the coil ?
Am I giving you crap instructions ?
I'm going to look for a couple of you tubes later, and if I find ones that I like, I'll post 'em up.
Going back to the .04 - .15v reading for a minute, the purpose of that test was to check the voltage amount supplying the coil, nothing more.
Try this when you get a minute :
With the ignition off, and a cold engine, attach the MM+ to the battery + and the MM- to the battery -. This should read +/- 12.6v, so let's just say 12.6.
With the ignition still off, keep the MM+ on the battery +, and put the MM- onto the block. A valve cover bolt head should suffice, for example. This should also read 12.6v.
This will tell you if the block is well grounded or not.
Assuming it is, remove the coil supply + wire from the coil, and put a piece of wood or rubber under it so that you don't inadvertently touch a ground with it. (Wood and rubber are non conductive)
Next, turn the ignition on, but do not run the engine.
Attach the MM+ to the + supply wire, and the MM- to the block (same point as you used earlier.)
This should read +/- 12.6 on a non resistor wire and +/- 9v on a resistor wire.
Post up your observations for info.
I had mentioned observing a miniature electrical storm in the HT leads in the dark.
If you want to see what that looks like, put all of your original HT wires, and coil, back on and look at the coil HT lead and number 8 lead.
Half way down the page on the left, under the section 'overview', it states 500 ohms per foot.
I made a note years ago that they said <500 ohms per foot.
One has to measure each HT lead, and then apportion 500 per foot to the actual lengths.
You said that all of the new HT leads were within spec. Hmm, ok.
I say hmm, ok, coz I returned an entire MSD box once, and exchanged half of the HT leads in another, because they read >500 ohms. Maybe I'm being fussy. I don't care, but my engine does.
Here's a you tube for info :
She uses a screwdriver. I wouldn't.
She measures each lead, but doesn't show the calculated guideline per wire as a comparison. (It's easy enough to calculate, but I'd be more impressed with the video if they were shown already.)
She shows that the total guideline should not be greater than 25,000 ohms. Yeah, ok, but over what length ?
Anyway, the point is that the her leads have different ohm values than the earlier MSD example, and that's why you have to check the specifications on your new ones, if you didn't already.
)
