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PostPosted: Tue Jul 30, 2019 4:48 pm 
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Definitely Cylinder 6. The injector test was pretty obvious - each other injector caused the engine to stumble just a tiny bit. Cyl 6 does not - no change at all unplugging the injector.

This is good I take it?

Rich

Here is the plug from #6 and had a heavy smell of fuel when I pulled it:

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PostPosted: Tue Jul 30, 2019 6:20 pm 
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Yes. That tells you the injector isn't firing properly.

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2007 Chrysler Town & Country Limited: Sold to neighbor
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PostPosted: Tue Jul 30, 2019 8:50 pm 
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Replaced the plug - still missing - still on #6.

I could try the old method of plugging the plug into the coil boot and laying it up against a ground but it looks like they are spring loaded so I don't know if it will stay connected.

Any other way of testing if the plug is getting power to fire it?

Rich


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PostPosted: Tue Jul 30, 2019 8:57 pm 
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Rich, you've got the right idea. Now if it was all cylinders on that bank I'd have you double check the ground strap that runs from the camshaft cover to the cylinder head (this started in 2004 on the Northstars). If the plug does not fire with a new coil, new plug, then I'd be leaning toward a bad PCM. I don't have the schematics handy but there will be a wire putting +12V to that coil, if that wire is not getting power there is the issue. If the plug was not wet with fuel I'd suspect a bad injector or injector wire circuit, which I will not rule out yet- but you need to see spark at the #6 plug.


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PostPosted: Tue Jul 30, 2019 11:01 pm 
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Here is the pinout for one of the coil modules - question is where should the 12v be and what is the control signal? I'm thinking that the pink wire is likely the 12v since it is the same color on all of them.

It would help to have an understanding of how the thing works too. Anyone?

Image

From the manual:
Code:
IGNITION COIL/ICM ASSEMBLY

Each ignition control module (ICM) has the following circuits:
An ignition voltage circuit
A ground
An ignition control (IC) circuit
A low reference circuit
The powertrain control module (PCM) controls the individual coils by transmitting timing pulses on the IC circuit of each ignition coil/module to enable a spark event.

The spark plugs are connected to each coil by a short boot. The boot contains a spring that conducts the spark energy from the coil to the spark plug. The spark plug electrode is tipped with platinum for long wear and higher efficiency.


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PostPosted: Tue Jul 30, 2019 11:34 pm 
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Ok I turned the key on and tested power on the pink wire and I have 12v on all the pink wires (tested 2 of them). My meter is likely not fast enough to catch voltage on the IC circuit to catch the voltage. I might be better off with a test light to see if the signal is there. Problem is the manual doesn't say how much voltage is supposed to be on that IC circuit.


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PostPosted: Wed Jul 31, 2019 12:37 am 
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I just ordered one of these: https://www.amazon.com/gp/product/B000OCKJDW/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1

Will be here on Thursday - going to wait - it will take all the guesswork out of the situation. It will test the plug and the coil pack.

Rich


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PostPosted: Wed Jul 31, 2019 11:47 am 
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OK, I'm a little confused but I will try to talk myself through...

1) You basically did a poor mans injector balance test. You pulled each injector plug and when you did, that caused a stumble on that respective cylinder. When you got to #6, nothing happened. That is the sign of an injector and/or the wiring to it either not firing at all, or very minimally (which I suspect as you say that the plug smelled like fuel).

2) The plug smells like fuel, which also tells me that the coil isn't firing. Again, swap #8 to #6 and see if anything changes. If not, then I would clear the coil of being a culprit.

I would start looking at wiring harnesses, looking for bad ground (mentioned about the strap above), all the way up to a bad PCM (but that would be last resort). It seems to me that #6 is not getting any signals through the harness.

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Retired Bonneville Owner and former GM Tech:
2004 Pontiac Bonneville GXP: Black/Ebony *SOLD*

Summer Toys: Combined 827 RWHP / 877lb/ft RWTQ
2004 Pontiac GTO: Impulse Blue Metallic/Black/M6: lots 'o mods, 415 RWHP / 405lb/ft RWTQ!
2006 Cadillac STS-V: Light Platinum Metallic/Light Gray/A6 - Spectre CAI, Magnaflow exhaust, Speed Inc. tune, 412 RWHP / 472lb/ft RWTQ

Daily Drivers:
2019 Chrysler Pacifica Limited: Mommy's new RGC
2015 Chrysler Town & Country Limited Platinum: Kids new RGC
2007 Chrysler Town & Country Limited: Sold to neighbor
2009 Pontiac G8 GT: L76, Sport Red Metallic
2003 Chevrolet Suburban 2500: Doeskin Tan - 8.1L Big Block... new plow truck
1999 Chevrolet Suburban: Sunset Gold Metallic - Daddy's winter beater and plow truck


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PostPosted: Wed Jul 31, 2019 12:17 pm 
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Actually I see it as no spark because of heavy fuel smell on the plug. That tells me that the injector is working, allbeit not how well it's working. If there is no spark there would be no stumble either because the cylinder is not firing normally. So now I'm trying to confirm power at the coil to confirm spark.

Now if there is spark AND fuel then what? Plug is being fouled out? Low compression in that cylinder?

Rich


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PostPosted: Wed Jul 31, 2019 12:32 pm 
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are you positive you have spark? leave 6 out but connected and see if you get good spark when you crank and idle.
if you do, then the mixture is too rich and wont fire - can you swap the injector easily to test?

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PostPosted: Wed Jul 31, 2019 12:37 pm 
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Not positive.. which is why I'm buying the tool. Can't easily test as you suggest because the boot on the coil is spring loaded and pushes the plug out. Not going to try to hang onto it while cranking :)

I do have +12v at the pink wire on the coil and the coil is brand new as is the plug. I just don't know if the pcm is telling it to fire or not.


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PostPosted: Wed Jul 31, 2019 1:41 pm 
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rwebb616 wrote:
Actually I see it as no spark because of heavy fuel smell on the plug. That tells me that the injector is working, allbeit not how well it's working. If there is no spark there would be no stumble either because the cylinder is not firing normally. So now I'm trying to confirm power at the coil to confirm spark.

Now if there is spark AND fuel then what? Plug is being fouled out? Low compression in that cylinder?

Rich


Which is why I have said, numerous times now, move the coil on #8 to #6 and move #6 to #8 and see if the misfire moves. If #6 works properly and #8 now misfires, you know it's a coil. If not, the coil is ruled out and becomes a wiring/harness/ground issue.

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2004 Pontiac Bonneville GXP: Black/Ebony *SOLD*

Summer Toys: Combined 827 RWHP / 877lb/ft RWTQ
2004 Pontiac GTO: Impulse Blue Metallic/Black/M6: lots 'o mods, 415 RWHP / 405lb/ft RWTQ!
2006 Cadillac STS-V: Light Platinum Metallic/Light Gray/A6 - Spectre CAI, Magnaflow exhaust, Speed Inc. tune, 412 RWHP / 472lb/ft RWTQ

Daily Drivers:
2019 Chrysler Pacifica Limited: Mommy's new RGC
2015 Chrysler Town & Country Limited Platinum: Kids new RGC
2007 Chrysler Town & Country Limited: Sold to neighbor
2009 Pontiac G8 GT: L76, Sport Red Metallic
2003 Chevrolet Suburban 2500: Doeskin Tan - 8.1L Big Block... new plow truck
1999 Chevrolet Suburban: Sunset Gold Metallic - Daddy's winter beater and plow truck


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PostPosted: Wed Jul 31, 2019 1:53 pm 
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I didn't really suspect the coil since they were all just replaced but it is certainly easy enough to do that test. I'm more suspecting no power at the plug to cause the spark, or if there is then there is something more serious going on.


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PostPosted: Thu Aug 01, 2019 8:57 am 
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put it on hold until the part arrives- its diagnosis time

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PostPosted: Thu Aug 01, 2019 9:11 pm 
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Ok I ran the first two tests on the box:
Image

I have spark with both - coil to ground and all the way through the spark plug as shown.

Now what? Could be a bad injector if it's not putting out enough fuel... could swap injectors if it's easy to change them... I have never attempted.

Rich


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PostPosted: Fri Aug 02, 2019 9:29 am 
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I'm hoping it's now narrowed down to a bad injector, possibly leaking/ getting stuck open. A quick way to test this is to turn the key to on with the fuel rail and injectors propped up above the injector ports so you can see the tips. If any one of them is leaking it will need replacement as it can wash down a cylinder with fuel (bad for rings, bad for cylinder wall) and if this has happened I would prefer an oil change be done as some fuel will likely be in the oil.

The last thing after the fuel injector would be to do a compression test on the cylinder. The car ran great here at the shop and a upon delivery to Sarnia Ontario. I gave the car a couple of good test drives as well. I would not expect any mechanical failures.


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PostPosted: Fri Aug 02, 2019 9:33 am 
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Fair warning, a leaking injector can fill a cylinder up with fuel and cause a hydraulic lock. I have seen a cylinder crack on a late 90's Aurora from this, bad injector was the fault. 2000+ Northstars have weaker connecting rods and usually hydro-lock on those will bend a rod. A bad injector is a good thing to catch early on, and it seems you might have.


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PostPosted: Fri Aug 02, 2019 10:44 am 
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I just went out and looked at it.. man those things are smaller than I thought. I was thinking they were a good 4 inches or so long based on the FSM illustrations. Anyway I haven't done the test yet because I need another person and they are not yet available but what I wanted to say is that I pulled the dipstick to check the oil - had no smell of fuel in it but that doesn't mean that it's not an injector. Just means if it is it's probably not enough yet to saturate the oil - hasn't been run for long in this condition and the oil was just changed I would say 500 or so miles ago. Or that could also mean there hasn't been any leak down yet which is a good sign too.

Like I had mentioned earlier I did notice a slight smell of oil on the tip of the first spark plug.

Rich


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PostPosted: Fri Aug 02, 2019 11:32 am 
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Or it hasn't gotten past the rings yet, which leads to the theory of hydrolock mentioned above. Crank it with the plug out and see if fuel sprays out.

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2004 Pontiac Bonneville GXP: Black/Ebony *SOLD*

Summer Toys: Combined 827 RWHP / 877lb/ft RWTQ
2004 Pontiac GTO: Impulse Blue Metallic/Black/M6: lots 'o mods, 415 RWHP / 405lb/ft RWTQ!
2006 Cadillac STS-V: Light Platinum Metallic/Light Gray/A6 - Spectre CAI, Magnaflow exhaust, Speed Inc. tune, 412 RWHP / 472lb/ft RWTQ

Daily Drivers:
2019 Chrysler Pacifica Limited: Mommy's new RGC
2015 Chrysler Town & Country Limited Platinum: Kids new RGC
2007 Chrysler Town & Country Limited: Sold to neighbor
2009 Pontiac G8 GT: L76, Sport Red Metallic
2003 Chevrolet Suburban 2500: Doeskin Tan - 8.1L Big Block... new plow truck
1999 Chevrolet Suburban: Sunset Gold Metallic - Daddy's winter beater and plow truck


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PostPosted: Fri Aug 02, 2019 11:35 am 
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Any way to crank it without starting? Remember the Bonneville has that kinda auto-start thing when you hit the key.


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