2.7 ignition spark issue - DodgeIntrepid.Net Forums - Dodge Intrepid, Concorde, 300m and Eagle Vision chat
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post #1 of 52 (permalink) Old 03-31-2012, 12:47 PM Thread Starter
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Exclamation 2.7 ignition spark issue

Hi all, I am totally new here and searched for some answers both last night and this morning, to no avail.

Symptoms = rough idle & loss of power.
Discovery = By removing each coil's connection one-at-a-time, I found that the coil on the front cylinder (left side, passenger, as I am facing the engine) when disconnected had NO EFFECT on the idle. Neither improving nor making it worse. Next, I removed a coil from another cylinder and that had NO EFFECT either. Thinking now is dead spark plug. Pulled plugs yesterday and changed with the Champion Platinum's. Fired it up only to have the same issue! I can still remove the coil connection to that cylinder with NO adverse affect in the idle.

I have NO check engine light at the moment. Due to disconnect of negative terminal during park plug change.

When this first began, I had the readouts printed by AutoZone. The error codes were 0300 - 0306 and 0172.

The car has over 200,000 on it and generally performs very well. Used 1/2 quart of oil on the trip to California recently.

I need some guidance from you younger guys that know these things. Chime in, point me to links... whatever you can provide, I'll be grateful

Thanks,
OldTimer
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post #2 of 52 (permalink) Old 03-31-2012, 03:07 PM
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P0172 is passenger bank is running rich. That could mean that the cam has slipped one tooth. I don't know if that's possible without other things happening since you have a timing chain, unless the timing chain is stretched or otherwise has lost tension.

Have you ever replaced the timing chain and water pump? It may need it.

What about all the other coils when you pulled their primary wires one at a time? You only mention two. It could be that you didn't notice anything because the computer compensates for the one cylinder and increases the fuel to the other cylinders to maintain the idle speed (closed loop control), so it would seem to you like there was no change.

You might also need to change the PCV valve (use aftermarket, not OEM) and its hose (use OEM, not aftermarket), and the crankcase vent hose (on the passenger side - goes from valve cover to intake tube).


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Last edited by peva; 03-31-2012 at 03:10 PM.
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post #3 of 52 (permalink) Old 03-31-2012, 03:11 PM
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well,, if the plug is not firing,, it too will cause a rich code, do this,, take the coil from the drivers side front,, and swap it with the bad one,, start and see if the miss moves with the coil,
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post #4 of 52 (permalink) Old 03-31-2012, 03:39 PM Thread Starter
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-Peva: Yes, I have disconnected ALL coils one-at-a-time. All but the one cause a noticeable increase in idle roughness. I understand the need and concern about changing PCV valve, hose & crankcase hose, water pump, timing chain, but at this time I am just focused on this firing issue.

DrDodge: Yep done that. All indications are that there is something awry with that particular cylinder.

Since posting this I have been told that it could be an open wire from the control unit to that coil.

I have also been told, it could be an injector failure on that cylinder. To find out if the injector has failed, I should start it and let it run for 5 minutes, then remove the spark plug and examine for gas deposits. If gas is present, injector is working. (Sounds logical to me).

I am about to perform the injector test in about 5 minutes.

I appreciate the input from ya'll, so keep it coming.

Thanks,
Dave
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post #5 of 52 (permalink) Old 03-31-2012, 04:03 PM Thread Starter
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Update: Just tested the spark plug for gas deposits. Couldn't absolutely swear that gas was present visually, but when I smelled of the plug, it was there!

While there, I just for grins swapped the front coil with the next one back with the same results.

Note: When I disconnect a good performing coil/cylinder, I can tell that it is working by the engine acting like it is about to die! When I remove the front coil's connection, there is absolutely no change in the engine speed or any increase in roughness!

What else can I do?
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post #6 of 52 (permalink) Old 03-31-2012, 04:16 PM
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Quote:
Originally Posted by OldTimer View Post
-Peva: Yes, I have disconnected ALL coils one-at-a-time. All but the one cause a noticeable increase in idle roughness...
I'm confused by your first post:
Quote:
Originally Posted by OldTimer View Post
...Discovery = By removing each coil's connection one-at-a-time, I found that the coil on the front cylinder (left side, passenger, as I am facing the engine) when disconnected had NO EFFECT on the idle...Next, I removed a coil from another cylinder and that had NO EFFECT either...

Last edited by peva; 03-31-2012 at 04:18 PM.
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post #7 of 52 (permalink) Old 03-31-2012, 04:31 PM Thread Starter
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Peva: I am sorry, but I don't understand what you are confused about. Maybe I am not being clear enough!

When I say I have disconnected the coils one-at-a-time of course the engine is running and of course I replaced each coil connection before moving to the next.

In my last update... I removed the coil from the troubled cylinder. I then removed another coil from a cylinder that is performing well. I exchanged the two coils. In other words I placed the suspected coil on the good cylinder and took the good cylinder's coil and placed it on the troubled cylinder. There was NO change in the performance of idle.

Does this help?
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post #8 of 52 (permalink) Old 03-31-2012, 08:57 PM
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Quote:
Originally Posted by OldTimer View Post
Peva: I am sorry, but I don't understand what you are confused about. Maybe I am not being clear enough!

When I say I have disconnected the coils one-at-a-time of course the engine is running and of course I replaced each coil connection before moving to the next.

In my last update... I removed the coil from the troubled cylinder. I then removed another coil from a cylinder that is performing well. I exchanged the two coils. In other words I placed the suspected coil on the good cylinder and took the good cylinder's coil and placed it on the troubled cylinder. There was NO change in the performance of idle.

Does this help?
Yes. I understood when you later said you swapped two coils. It was at best ambiguous how you said it in your first post - When I go back and read the first post, I still would never read that as saying that you swapped the two coils. Removed its connector, maybe, or you simply removed the coil - I did not read it as swapping the two. It's safe to say that DrDodge also didn't read it the way you apparently meant it since he suggested swapping the coils. Can you see how I *was* confused (by your first post)?


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post #9 of 52 (permalink) Old 03-31-2012, 10:07 PM Thread Starter
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Peva: It's ok! Bottom line is a got a 1999 Intrepid that belongs to my wife and isn't capable of getting her to Walmart. Perhaps now you understand my plight better. ;-)

I need help getting down the Troubleshooting Lane! I'm totally out of ideas.

Well, at 70 years old I'm not sure had that many in the first place! But now I digress.
Dave
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post #10 of 52 (permalink) Old 03-31-2012, 10:19 PM
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ok,, time for a compression test,, and time to see if you have injector pulse
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post #11 of 52 (permalink) Old 03-31-2012, 10:44 PM Thread Starter
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DrDodge: "time to see if you have injector pulse," Where would I begin? What do I use?

I can get a compression test done. Will pursue that tomorrow.
Thanks,
Dave
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post #12 of 52 (permalink) Old 04-01-2012, 01:35 PM Thread Starter
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There is NO voltage present on the wires that attach to each coil when the ignition is ON. Should there be a voltage present or not?
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post #13 of 52 (permalink) Old 04-01-2012, 02:11 PM
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If you're measuring across the two wires, then you will get 0 volts. If you measure from the dark green/light green wire to ground, you should then get +12V.

But for it to be running at all, you have to have coil and injector supply voltage. So I don't think that is your problem - unless you see zero volts from the dark green/light green wire to ground on that one cylinder. Another possibility is that the PCM output/driver for that cylinder is kaput.

The dark green/light green wire is the power source for the coils. The other wire (tan with another color stripe for each coil) also will be at +12V except when firing (hence the 0 volts reading when it's not running). The coil gets fired by the PCM pulling the tan/xx wire to ground momentarily and then releasing it. (Being an "Old Timer", you remember how points work, right? It's done just like that, except with electronics.)

BTW - the injectors are powered by the same fuse (Fuse S) and their high sides are also dark green/light green wires. They work the same way - the other wire gets grounded by the PCM to open the injector. That's just to explain how it works. Again, Fuse S has to be good if it's running at all.

You might want to download the FSM and use the schematics (Section 8W) to troubleshoot it efficiently.


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Last edited by peva; 04-01-2012 at 02:35 PM.
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post #14 of 52 (permalink) Old 04-01-2012, 03:01 PM Thread Starter
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Hi Peva, I guess once again I am vague in my explanations. Sorry! I measured from each of the two wires to the Negative battery connector on the strut tower.

I randomly selected two coils and the suspect coil and NONE have ANY voltage present with the ignition key in the ON position.

I just did this again after reading your message! I measured from each of the two wires to that negative battery point... NOTHING!

I don't know what fuse S is, but there is a fuse in the box under the hood that indicates for coils/injectors, 20amp. I guess that is the one you are speaking of. I removed it checked it with ohm meter and it is fine.

Will look at section 8W and see if I can understand anything.

Any additional suggestions would be greatly appreciated.
Thanks again,
Dave

After looking at the wiring diagram I decided to remove the fuse (20amp injector/coils) and take a voltage measurement there. I found 0.01 on the leg nearest to the firewall. The other leg, of course, had zero.

So if I am reading this correctly, that means that there is something wrong at the Automatic Shutdown Relay. It appears to be the same relay as the one next to it. Perhaps I can swap these to see if there is any change in symptoms.?

Last edited by OldTimer; 04-01-2012 at 04:06 PM. Reason: Edit: After looking at wiring diagram.
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post #15 of 52 (permalink) Old 04-01-2012, 03:52 PM
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No problem.

Again, if there truly were no voltage (relative to ground) at the dark green/light green wire of all the coils, there is no way the engine would be running a-tall because the coils would have no electrical power. Make sure your meter leads are making good metal-to-metal contact.

Often, the electrical connections on these old cars have surface corrosion that may look like you can get good electrical contact just by pressing the meter lead tips to the metal, but there is an invisible corrosion that is insulating the metal from good contact with the meter lead tip. This can be especially true of body/frame/chassis parts that you are trying to use as ground point (because they are so exposed to the elements).

To test what I am speaking of there, put the meter in resistance (ohms) mode, and touch both leads to the same piece of metal but not touching each other. If there is that insulating surface corrosion that I was talking about, you will get high ohms reading (typically several mega-ohms, or "Over Range" indication). If both leads are making good contact, you should be reading less than 1 ohm.

I've seen it where you can press really hard with a pointed tip where it appears to be digging into the metal, and all you're doing is indenting the metal under the corrosion without busting thru the corrosion, and damaging the lead tip in the process - you might see the meter start to shift into a lower ohms reading, but only briefly as you wiggle the probe around. You might need to burnish down to the metal with crocus cloth/sandpaper/emory cloth. After doing that, test that area with the two leads in ohms mode again - then make your measurement. (Don't forget to put the meter back into volts mode before putting the leads across voltage!!)

A tip: You might want to go by Radio Shack and pick up a pack of jumpers (several in a pack for a few dollars) with alligator clips on both ends. That way, if you want one meter lead on one point (such as ground) while you move the other lead around to different other points (for voltage readings or whatever), you can focus all of your attention on placing the second lead where you need it for each measurement. (You can also get meter leads with alligator clips, but the jumpers work just as well and give you more versatility, and for less money.)

Radio Shack jumpers to consider (the larger ones would be better for connecting a meter lead to a convenient ground point):
http://www.radioshack.com/product/in...ductId=2062660 (ten small 30" long - $7.99 cat. no 278-1156)
http://www.radioshack.com/product/in...ductId=2062661 (eight small 24" long - $6.99 cat. no 278-1157)
http://www.radioshack.com/product/in...ductId=2062622 (four large 30" long - $7.99 cat. no. 278-001


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Last edited by peva; 04-01-2012 at 04:22 PM.
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