coil pack

I have a question about coil packs, how do you test them ? 
Was reading on a forum that you use a ohm meter to check continuity ( plug 1 to 6 ) etc 
But their must be a better way to test it ?
I am working on an 2003 jeep tj 4.0L, has a misfire on #1 when it warms up .
 

Paul Danner has a great video of this technique;  That I can't find at the moment!!!!

Coil Output Test;

Connect a test lamp to ground, with the engine running put the tip of the test light beside the plug boot at the coil, slowly remove the boot and keep the the tip of the test lamp closer to the coil tower than the boot.  You want the spark to start jumping from the coil to the test lamp tip.  Compare against the other coil towers and see how far away you can pull the tip away.

You should at least get an inch away with a well defined blue spark.

The ohmmeter isn't much help in this case, because coils need to be tested under load and increasing heat.

You could also use a Spark Tester that has a KiloVolt scale and is adjustable on the plug end of the wire, you should have spark between 12-20 KV.

Now the fact that it misses when it warms up,  could potentially point to other issues,  lean injector, valve sealing issue, cylinder head gasket.  

Has there been any slow coolant loss?

Unfortunately, the coil pack is one bar that does all six cylinders, The injector I changed as the coating on it had cracks in several places, Have done compression test, cold and hot no change.Does not leak anti-freeze or go low.Has all new plugs.Went to a salvage yard and picked up a coil pack cheap, still have a miss but not as bad, Went for a drive and it does not stall when you stop at a light.I am leaning towards the coil pack not being good.With electronic ignition, how do you fine tune the timing?I did TDC on #1 compression stroke, checked the camshaft sensor placement.

Wow, you just gave me flash backs! I haven't seen that big stupid inline six coil pack in YEARS! The first generation had a different pin configuration than the later ones (no start nightmare). I keep plug wires laying around from Chevy 4.8/5.3/6.0L V8 engines to check that style ignition coil on newer engines with a similar ignition coil design. Usually you can pull the rubber boots off the coil and replace them with plug wires for testing. This makes it much easier to check spark out put of individual coil towers.
(PS: nobody knows what a TJ is outside of your Jeep circle. If you require further assistance, please provide the year, make and model of whatever you are working on in plain English)

Well it is a 2003 Jeep Wrangler TJ sport
4.0L inline 6

Usually you can pull the rubber boots off the coil and replace them with plug wires for testing. This makes it much easier to check spark out put of individual coil towers.

This is excellent advice, thank-you Noah.

How have you identified the Misfire is on cylinder #1?

I attached the Timing Procedure for you.
 
 
 

You could do a voltage drop test from fuse 28 to the coil on the power feed to make sure you have adequate voltage while the engine is running.

 Have done compression test, cold and hot no change

A good o'l compression test will only tell you if that cylinder has compression, but it won't verify any small leaks that can result in misfires.  A leak down tester is required at this point, or a scope with in-cylinder waveforms and intake and exhaust cranking waveforms to help rule out engine mechanical issues.

Another thing these older Throttle body engines were prone to was a rough idle, but run great at higher RPM.  The problem was wear in the throttle plate shaft and wear on the linkage.  The plate would close a few thousands of  inch, the IAC motor would go full open to try to account for this.  You IAC counts at idle would be useful information.

I personally have had the pleasure to never have worked on one of these engines!  But would guess on the linkage side of the throttle body there is a welch plug that you can drill out and there is a screw that can be adjusted just a bit to open that plate up  a little.

You can also try a little test, open up the throttle and place some thin shims between the stops, let the engine settle, did the misfire go away?

This is just some stuff to help you along, you did state the other coil seemed to improve the situation, maybe a new high quality coil will be the fix.
 



 

Thanks for the information, I don't have a scope so getting the wave form is out, 
As for the the other, think i can get through them, might take a bit.
The code that comes up from time to time is PO301
will post what i find .

Ok , did the power drop test and all is good as far as i see it 
checked the fuse #28  .... 12.5 v not running best as i can tell as it cuts out to quick,
                                          13.9 v when running.
backed probed the coil plug #2 wire  ...  12.5v not running.  didn't try it running.
Figured that should work, to show if their was a power drop in the wiring. 

Hade to order a cylinder leak down test kit , talked to everyone i know and no buddy has one.
will be in Wensday i am told. 

In the mean time, used a feeler gauge to shim the throttle stopper on throttle body to see if it made any difference, 
it does make a difference, let it sit and run til it was up to temp, does help.
removed the throttle body and adjusted the stopper a bit ( its a set screw put in from the bottom)
gave it one turn, that was too much, took it back off and backed it off half a turn.
Does idle better, that miss is slowly going away, 
Looking like a bunch of small things not just one big one, 

Ok let's do the voltage test over, we will check to make sure power and grounds are good to the coil so it has everything it needs to do its job.

With the engine running set the Volt Meter to DC Volts.  Positive lead to fuse 28 and the negative lead at the coil back-probed into the power feed wire.
The Volt Meter should not display above 0.250 volts or 250 MilliVolts. If it is greater there is not enough voltage getting to the coil. The wire may have high resistance or any of its connectors.  This power feed also has a splice and feeds the Auto-Shutdown Relay too.  It's in the wiring diagram I provided.

Same Voltmeter setup, except one lead on battery ground and the other on coil ground ( this coil grounds to the motor, so either a fastener or the underside of the coil if there is metal)
Again nothing over 0.250 volts or 250 millivolts.  If there is the ground needs cleaning.
 

With the engine running set the Volt Meter to DC Volts.  Positive lead to fuse 28 and the negative lead at the coil back-probed into the power feed wire.
The Volt Meter should not display above 0.250 volts or 250 MilliVolts. If it is greater there is not enough voltage getting to the coil. The wire may have high resistance or any of its connectors.  This power feed also has a splice and feeds the Auto-Shutdown Relay too.  It's in the wiring diagram I provided.
Did this part and got 0.18 volts .

Same Voltmeter setup, except one lead on battery ground and the other on coil ground ( this coil grounds to the motor, so either a fastener or the underside of the coil if there is metal)
Again nothing over 0.250 volts or 250 millivolts. 
On this part had a hard time getting a reading, did it several times but nothing over 0.15 volts

going to spend some time tomorrow cleaning up the bolts attaching the coil as they are the things i can see that will ground the coil to the block.
will retest it all after wards. 

Jerry, those are good numbers, so power and ground suppply is not an issue for the coil.

One thing i did find is that my PO301 code is not comming up , but now its an PO303 code that is showing up,

Not sure what you are using for a scanner, but at this point knowing how the PCM is handling fuel control can be a very good help.

I'm gonna assume you've replaced all the plugs?

Did you swap any plugs or injectors to produce the P0303 from the P0101?

If you are confident spark is good, the only thing left is lean or dripping injectors ( fuel trims may be of help here) or compression issues.

 

Put all new plugs in it before i posted the problem, in the beginning i was thinking ( look at the simple things first ) even replaced the #1 plug to see if i got a bad plug.
Have not moved or changed them since,
I'am leaning towards the wireing harness for the injectors, is thier a good way to test them ?
my thoughts are they are old, and the heat is never good for wires.

The best way to test the wires is with an oscilloscope, wiggle the wires and check for dropouts or collect enough data that when the PCM records a misfire you can check for possible dropouts.

Are you able to get fuel trim data?  Because if the O2's are working correctly, positive trims at all engine loads is a good indicator of fuel delivery,  so it is possible to have a lean injector.

The injectors are ground side switched, the PCM grounds them to fire them, but they all share the same power supply from fuse 28. 

 

Ok thanks , I dont have a fancy scan tool, I do have a code reader ( Innova 3100 ).
Just checking all the grounds , battery to block is not good, cleaned it and tightened it.
at drivers rear, block to body then hood, is broken at block. picked up a new one today just need to get time to install it.

Was looking at different scaners , what are your thoughts on the TAPDON AD500 ,
not sure if it will give me the info to me need .

I personally wouldn't consider anything less than the TopDon Artidiag 800BT.  You get lifetime updates and its FCA approved throught AutoAuthority for non-professional use. It has both types of OBD2, Global ( mandated by laws) and the Enhanced side which is manufacturer specific that usually comes with annual subscription costs.  This tool is Lifetime Subscription!!!

This scanner has the most bang for your buck!!!

All I use are a Launch Pad 7, Thinktool Pros, then a bunch of factory Scan tools. 

 

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have had thies for over 5 years, can they have anything with the problems i'am havein ?