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Discussion Starter #1
I've got a '97 Sable Vulcan with what feels like a misfire or simply slightly rough running, but only at idle. Otherwise, the car seems fine. I tested the coil today, and these are the numbers I got:

primary: 1.8 or 1.9 Ohms from the blue/white pin to each of the other three.
secondary: I get infinity (or zero, I forgot to check continuity) between each of the towers and any other *except* for the one across from it. For each coil tower *pair* (mine looks like the diagram below, and I mean when measuring A-B, or C-D, or E-F) I get a very consistent 14.8 or 14.9 kOhms.

A B
C D
E F

The primary seems out of spec (0.5 to 1.0) but, depending on the sources, the secondary resistances seem normal (12.5 to 16.0 kOhm).

What does a higher-than-expected primary resistance indicate, is it likely the cause of my slightly rough idle, and lastly, should I replace the coil pack?

I should note that I've recently replaced the DPFS (or whatever the egr-related switch is), tested the egr, replaced the TRS (twice), cleaned the MAF (properly), carefully cleaned the throttle body (but did not remove it), and replaced the wires and plugs. And yes I've run fuel injector cleaner through it. The plugs look *great*. Mileage seems to hover around 24, but that is 50/50 mixed highway/city.
 

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The coil pack resistance readings seem ok.

If the engine seems to be running ok at rpm or up hill with a load on it I'd not suspect the coil pack.

If it misses on a grade when the engine is lugged, maybe suspect spark plug gap.

Does it idle up ok when you turn the A/C on???? if not maybe suspect the IAC (Idle Air Control) it is a common problem part.

Vacuum leaks come to mind too.

If you still suspect the coil pack, most autoparts stores will bench test it at no charge.
If the problem seems to happen on a warm engine, maybe take a hair dryer along to heat the coil pack up for the bench test.

More trouble shooting thoughts for pondering.
Let us know what you find.
 

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Discussion Starter #3
QUOTE (pawpaw @ Jul 18 2009, 09:56 PM) index.php?act=findpost&pid=740511
The coil pack resistance readings seem ok.

If the engine seems to be running ok at rpm or up hill with a load on it I'd not suspect the coil pack.

If it misses on a grade when the engine is lugged, maybe suspect spark plug gap.

Does it idle up ok when you turn the A/C on???? if not maybe suspect the IAC (Idle Air Control) it is a common problem part.

Vacuum leaks come to mind too.

If you still suspect the coil pack, most autoparts stores will bench test it at no charge.
If the problem seems to happen on a warm engine, maybe take a hair dryer along to heat the coil pack up for the bench test.

More trouble shooting thoughts for pondering.
Let us know what you find.[/b]
I'll try to take these in order.
Whenever I leave my house, half of the directions I might go take me down fairly good sized hills. When I return, then, I am headed uphill, at a good grade, for several minutes at least. The car doesn't seem to miss but id does ping pretty good up these hills. Otherwise I never detect any pinging. Under load the car runs great.

The spark plug gap is very close if not perfect, as I checked them when I put them in, and as it turns out this is actually the second set of plugs I've tried. They are dual platinum autolites.

When the A/C is on, it does idle up and down as the clutch kicks in and out.

Whenever I've pulled plugs they all look great - the car runs well pretty much except at idle, at which point it has a slightly rough idle - not even enough to move the rpm gauge, but you can feel it through the steering wheel, exhaust note, and through your seat. It's almost like a partial misfire.

I guess I'll have to find a way to check for vacuum leaks - I've already gone around and listened very carfully (several times) to eat hose, and wiggled it, and so on.

I forgot to note that I've also replaced the fuel filter and checked the PCV valve and lines - they are nearly perfect.

Regarding the primary coil resistance - what does a higher than expected primary coil resistance even indicate?

When a parts shop "bench tests" the coil, what do they do?
 

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I would look the coil over for cracks in the insulation. This may show up as a miss. You can also mist the coil with water to see if that triggers a miss.

The primary resistance should be very low. It is a large wire that is nearly a direct short.
 

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Get a can of starting fluid and spray all the vacuum hoses ,but slowly , one at a time. If the idle goes up you found your leak. Old trick from my past. very cheap and effective. Same with plug wires and coil packs ,but use a water spray bottle. If the engine misses or stumbles ,replace it. My humble and usually wrong opinion says that your miss sounds like a partly clogged injector. get some b-g injector cleaner or seafoam and lucas fuel system cleaner. put a good dose of lucas (5 -10 oz) in the tank and add some gas to mix it in. suck the injector cleaner through a direct intake vacuum line by dipping a small hose that you added to the vacuum line , into the injector cleaner while someone high idles the car. do not let it stall ,but try to get the motor to stumble . suck a half can or so , then let the motor flood and stall. re-connect the vacuum line , let the motor sit a half hour and fire it up.watch the plumes of white carbon smoke kill the neighborhood kids and see if the motor runs better.
 

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Well the difference in the coil packs expected primary resistance, may be due to the accuracy of your test meter, or the scale you were measuring on, but a bench output voltage test would likely tattle on any output problems.

Not sure what parts stores you have in your area, or what test equipt they have, but in my area, the coil pack gets an output voltage test, along with some others.

The ping that you hear on a pull up a grade shouldn't be there & may be a clue on the random idle miss that you feel.

Something as simple as an old worn out PCV valve, that's clean inside & rattles when shaken, but not sealing well when it should, because it's worn inside, could cause an unprogrammed for vacuum leak, that'll cause mischief, so if it's due, or past due for replacement, why not change that low cost puppy out????

Are you using the specified heat range plugs in your engine????

Is the cooling system in good condition & is the thermostat keeping coolant temp in check????

Is your 3.0L Vulcan a flex fuel engine????

More thoughts for pondering.
 

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Discussion Starter #7
I'll try to take these in order again. I also forgot to mention that the cam synchro was also replaced at the same time that other stuff was (although the DPFS and the TRS were slightly later).

Today I replaced the PCV valve (it was cheap). No change.

I have been running fuel injector cleaner for 1/2 of a tank now, Chevron Techron. Periodically I've also run other stuff like the O'Reilly Auto stuff, etc.. when the mood hits. No change.

The multimeter I used (digital) is auto ranging and fairly accurate - I have used it for much more sensitive projects (electronics and motorcycle stuff) in the past. I note the primary coil resistance is clearly out of range, but what I don't know is what that *really* means.

I put one of those "show me the spark" sparkplug things on the front three today (in turn) and they all seem fine, but since I wasn't *in* the vehicle it was also hard to tell if it was misbehaving, too.

Since somebody made note of it, I've been paying much closer attention and, unfortunately, the car *does* ping even on mild acceleration, uphill or level. It /really/ pings good (no check engine lights) on uphills which is why I noticed it.

So, lots of pinging (or at least some kind of preiginition - it's certainly not knocking). It sounds like my old Buick 350 when I used 87 octane. I'm using good quality 87 octane, now, too.

Yes on the plugs - I don't recall the exact number but they are the recommended autolite dual platinums.

Cooling system just got flushed not 3 weeks ago - it was good then and should be perfect now. Never overheats, temp gauge comes up just so, laser themometer thing shows 180 to 195 on the stuff I can get at, and for the brief period I could borrow a scan guage it showed 195 to 205 but never more.

Lastly, it's not a flex fuel engine but all the gas around here has 10% ethanol.

Odd that it's pinging. The engine was very well taken care of by the previous owner - at or before scheduled maint. and always with high quality everything.

I've also done the "water in a spray bottle test" without luck. No change, no misbehavior, nothing.



QUOTE (pawpaw @ Jul 19 2009, 07:26 AM) index.php?act=findpost&pid=740553
Well the difference in the coil packs expected primary resistance, may be due to the accuracy of your test meter, or the scale you were measuring on, but a bench output voltage test would likely tattle on any output problems.

Not sure what parts stores you have in your area, or what test equipt they have, but in my area, the coil pack gets an output voltage test, along with some others.

The ping that you hear on a pull up a grade shouldn't be there & may be a clue on the random idle miss that you feel.

Something as simple as an old worn out PCV valve, that's clean inside & rattles when shaken, but not sealing well when it should, because it's worn inside, could cause an unprogrammed for vacuum leak, that'll cause mischief, so if it's due, or past due for replacement, why not change that low cost puppy out????

Are you using the specified heat range plugs in your engine????

Is the cooling system in good condition & is the thermostat keeping coolant temp in check????

Is your 3.0L Vulcan a flex fuel engine????

More thoughts for pondering.[/b]
 

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OK, more good feedback.

Not likely any need to fixate on the coilpack primary resistance, as I understand it Ford doesn't specify a primary resistance & yours is within a normal expected range.

The secondary is specified & yours is within spec, you haven't posted any misfire codes, you've done a coilpack wetdown test & other than ping, you say the vehicle runs normally. So I'd set this aside for now, unless you come by some clues that would call for another look.
If you just can't set it aside, pull the coilpack & have it bench tested.

I would be more concerned about the ping problem, as it could cause more than aggrivation, like engine damage!!!!

Also finding & fixing the ping problem, may also fix the random idle miss.

Did the idle miss & or ping problem come about suddenly after some event, or slowly over time?????

Is there any change in the miss or ping between the vehicle being cold & fully warmed up????

Is there any difference in the idle miss when the vehicle is in gear, or in "N" or "P"?????

When you checked vacuum lines, did you also check the evap system vacuum line between the intake manafold & the vapor recovery canister???? It's a common vacuum leak source when it dryrots & cracks, that'll also cause engine ping, as I found out on my 94 3.8L.
 

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I assume your car has a SPOUT plug ... are you sure the plug is in place and making a good clean connection. The pinging sounds like a timing problem.
It wouldn't hurt to check the timing advancement with a timing light.
 

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Discussion Starter #10
QUOTE (Gary123 @ Jul 19 2009, 10:46 PM) index.php?act=findpost&pid=740688
I assume your car has a SPOUT plug ... are you sure the plug is in place and making a good clean connection. The pinging sounds like a timing problem.
It wouldn't hurt to check the timing advancement with a timing light.[/b]
What is a SPOUT plug?

EDIT: I don't think I have a SPOUT plug, mine is a '97.

I did clean the MAF, but is there an easy test for the MAF (like a voltage test?)

My understanding is that the EGR comes in to play mostly when steady state cruising - I have pinging even under light acceleration, so it shouldn't be the EGR.


Also, the idle miss seems to be slightly worse in N or P, and it only misses when fully warmed up.
I've had the car less than 3 months, but I don't recall it pinging nearly this bad. The car did sit for almost a year between owners, but the previous owner (a good friend of mine) says it did not ping for him.
 

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The SPOUT plug is an electrical jumper that connects the ECU spark advance signal to the ignition module.
You may be right, the '97 engine may not need this connection ... but I would check the timing advance with a timing light to make sure the spark advance is working.
 

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The SPOUT plug is on the '97 Vulcan. it will pull 2-3 degrees globally. It's hanging off the PCM wire bundle. Dark Green and Gray/Red wires.
 

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Discussion Starter #13
I listened and checked every vacuum hose I could find very carefully - I can't find a vacuum leak. I'll try again with some propane one of these days if I have to.

This is where it gets interesting: I did find the SPOUT plug (thanks for correcting me!) and pulled it. At first, things seemed better, but once up to temp they were just as bad if not worse. Coming up one of the big hills near my house on the way home today it pinged much worse than usual (SPOUT plug *unplugged*) and I could tell it was pinging all the way from 1800 through about 3000. MUCH worse in higher gears (more load). The "tone" of the pinging was different, slightly. Almost like it was happening less often but when it did happen it was worse. It was pretty bad, actually.

Where does that leave us? MAF sensor? TPS? Injectors? EGR?

EDIT: Called local Ford dealer. They suggested that I replace the Autolite DP plugs with Motorcraft. For the previous 20K miles the plugs have been fine, but ya never know. At $7/each I'm a bit hesitant - I could almost get a coil for that.
 

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With the idle miss Not being there when the engine is cold & the air/fuel ratio is richer & it missing after it's warmed up & the air/fuel mixture is leaner & it pinging when climbing a hill or crusing, I'd sure suspect a vacuum leak somewhere.

But right now your suspect list is still long & your right, the MAF, O2 sensors, injectors, fuel pressure, intake valve & combustion chamber carbon deposits, engine temp, timing, fuel quality, intake air tube downstream of the MAF, leaking air, vacuum leak/s & listening for it isn't gonna get it, you need to do a visual & physical inspection, of everything subject to vacuum, from the AC/Heater controls, to the brake booster, to the evap system, to the intake manafold gaskets, to the PCV valve hoses & grommet fittings, or do a propane sniff test to look for a rpm rise at the vacuum leak. EDIT: Lets not leave the EGR system out just yet either.

Your 97 Sable is 12 years old now, so imo those evap hoses belong high on your suspect list, mine were dryrotted & cracked by then & I also had intermittent raw fuel odors in the cabin, along with an intermittent ping on a pull.

When I finally stumbled onto the dyrotted vapor recovery line connection at the out of sight "T" connection under the battery tray & fixed it, both the ping & in cabin raw fuel smell problems were fixed.

Have you had the computer scanned for trouble codes???? If not I'd do it anyway, as you could have codes stored in memory that have yet to turn on the CEL & they may offer up good trouble shooting clues.

If your auoarts store won't scan the computer unless the CEL is on, just loosen the gas cap before the drive over there!!!!
Any port in a storm....Right!!!! lol

Keep us posted on your findings.
 

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Discussion Starter #15
One thing to keep in mind is that I'm told *all* of the Vulcans are slightly un-smooth at idle. Perhaps that is what I'm feeling. I used to have an Accord with the 3.0L and you could hardly tell it was running, you almost had to put your hand on it to be sure. So perhaps that's just a red herring.

That said, tonight I pulled the battery (and battery box) and there no vacuum hoses beneath it. :-(
I put it all back together, went over every vacuum hose I could find oh so carefully (with the engine running) and found /nothing/, except perhaps a barely audible hiss coming from a vacuum box on the firewall, right above the steering, where one *big* vacuum hose goes in, several fairly small ones come out, and one larger one also exits to the intake manifold (near or at the MAF). I couldn't find anything that didn't look just fine - the rubber is very pliable in general and seemed to seal well.

I took it for a drive and as it came up to temp... no pinging.
Until I went up a hill. In 1st and 2nd, little to no pinging. In 3rd, plenty of pinging. In 4th, *lots* of pinging. I drive like there is an egg on the gas pedal anyway but I did notice that.

I'd be surpised at intake valve and combustion chamber deposits, I've run so much stuff through over the last 5 tanks....

Other than this pinging, it runs well. I get 24 mpg in mixed highway/city. It starts well (never hard), comes up to temp and stays there, the A/C works well and the heat will just about kill ya. I'm afraid this pinging issue is the start of a bigger problem. I think I'm going to try to leave well enough alone for a bit. Maybe tomorrow I'll replace the plugs and while at the dealership see if I can get a coil to test with. I don't think it's the coil either but a weak spark can cause an over-rich condition which can also cause pinging. Battery, BTW, is also new this year.

In the daylight, I'll try to get a closer look at those EVAP hoses and such.
 

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Discussion Starter #16
Tried something weird today.
Checked no. 5 plug (center front) - it looks just fine. It's an autolite AP764.

Got it warmed up (ping).
Shut it off, pulled the MAF sensor plug.
Went up big hill.
If I tried *really* hard I could get it to /barely/ ping.
I shut the car off, re-connected the MAF, and tried again. Ping.
And again, I shut the car off, disconnected the MAF sensor, and it would ping but only barely and I had to try.
Then my check engine light came on.

I'm going to see if a MAF can be "tested" and start pricing them out.
 

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OK, good test & feedabck.

If you have cleaned the MAF sensor, did you use a non residual cleaner, thats formulated Not to leave deposits when t dries????
If not, maybe consider cleaning with something like CRC MAF Sensor Spray Cleaner. Be sure to remove the MAF sensor & let it cool before cleaning & be careful not to touch the sensor part with the spray nozzle, or recontaminate it on installation.

Let us know how it goes.

EDIT: Here is a good read on Ford MAF sensor poblems.
http://www.fordscorpio.co.uk/maftest.htm
 

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You should disconnect the battery to clear any learned fuel trims. When you disconnected the MAF you are running off a default mode table in the PCM for fuel mix. Any learned values are applied the fuel trims that are used in conjunction with this table.

How old are the O2s?
 

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Discussion Starter #19
The O2 sensors are original. Car has 101K miles on it.

I used CRC MAF cleaner, didn't break or touch the wires. Just got it put back together 5 minutes ago. I'll run out real quick and disconnect the batt.
 

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Discussion Starter #20
At the end of my workday I hooked up the battery, fired it up and went for some errands. No pinging detected. HOWEVER, it was raining, but temperature-wise it was similar to other days when it has pinged like mad. I expect I'll have plenty of opportunity to see how it behaves but if this holds true I'll hardly believe it. Here is keepin' my fingers crossed.
 
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