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My car was showing a P0302 code which is a cylinder 2 misfire. I had it checked by the scanner at Advance Auto and also by Tony2005's scanner. So I take the car into the dealership and they're saying that my #6 fuel injector is bad. Why is the dealership saying the #6 injector is bad and two other scanners saying #2 cylinder? Is the dealership wrong or is their computer just more accurate and the scanners are wrong?
Thanks
"Why do we drive on parkways and park on driveways?"
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Originally posted by Silversvts:
My car was showing a P0302 code which is a cylinder 2 misfire. I had it checked by the scanner at Advance Auto and also by Tony2005's scanner. So I take the car into the dealership and they're saying that my #6 fuel injector is bad. Why is the dealership saying the #6 injector is bad and two other scanners saying #2 cylinder? Is the dealership wrong or is their computer just more accurate and the scanners are wrong?
Thanks
Won't know til they try n fix it. But if it is showing a misfire that is usually spark and not a fuel injector issue. Dealership could be wrong, but I hate those guys anyways. The monkeys that usually work their don't have a clue. 
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Originally posted by Silversvts:
My car was showing a P0302 code which is a cylinder 2 misfire. I had it checked by the scanner at Advance Auto and also by Tony2005's scanner. So I take the car into the dealership and they're saying that my #6 fuel injector is bad. Why is the dealership saying the #6 injector is bad and two other scanners saying #2 cylinder? Is the dealership wrong or is their computer just more accurate and the scanners are wrong?
Thanks
The OBD-II system does allow dealer-specific codes, these codes will be a P1xyz code and may include codes for fuel injectors, etc. I have an OTC Genisys scan tool which will allow me to retrieve the dealer-specific codes as well as monitor some dealer-only parameters in the datastream mode. There are parameters for fuel injector faults which the Autozone readers will not see but show up during the datastream mode.
The misfire indication uses the knock sensor and camshaft position sensors to determine which cylinder the PCM thinks is misfiring. There is a [small] chance that a bad injector on cylinder #6 could cause a misfire on cylinder #2 report.
What I would do is use my scanner to determine if the air/fuel ratio is going lean or rich during a "misfire" to determine if unburned fuel is getting into the exhaust. If the mixture goes rich, then you probably don't have spark (which would indicate a bad plug, wire, or coil). If the mixture goes lean, then you may not be getting enough fuel (bad injector).
Do cylinders 2 and 6 share a coil by chance (I don't have my service manual handy)?
-Rod
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Originally posted by SHOrod:
What I would do is use my scanner to determine if the air/fuel ratio is going lean or rich during a "misfire" to determine if unburned fuel is getting into the exhaust. If the mixture goes rich, then you probably don't have spark (which would indicate a bad plug, wire, or coil). If the mixture goes lean, then you may not be getting enough fuel (bad injector).
Do cylinders 2 and 6 share a coil by chance (I don't have my service manual handy)?
-Rod
I just changed the plugs, wires, and the coil. This is the configuration of the coil pack:
4-6-5 <--coil pack
3-2-1
I don't know if they share the same coil or not though.
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I'm not sure if your Contour has 3 coil packs or not. In the configuration you show, if you have three coils, then cylinders 2 and 6 DO share a coil. That could explain why you might actually have a bad injector but the PCM is reporting a misfire on cylinder #2. If it were me, I'd want to see the lean/rich reading or the factory scan tool report an injector #6 fault to be sure. Neither the injector nor the coil are inexpensive.
-Rod
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Originally posted by SHOrod:
I'm not sure if your Contour has 3 coil packs or not. In the configuration you show, if you have three coils, then cylinders 2 and 6 DO share a coil. That could explain why you might actually have a bad injector but the PCM is reporting a misfire on cylinder #2. If it were me, I'd want to see the lean/rich reading or the factory scan tool report an injector #6 fault to be sure. Neither the injector nor the coil are inexpensive.
-Rod
It's one coil. The only cars (to my knowledge) to have a 3 coil set up are the GM 3800 series II.
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Wastefire? Here is a diagram post by Favorite Mystaque which should explain the 2 coil- 6 injector connection. Look at the bottom right.
Originally posted by FavoriteMystaque:
Here is a firing order diagram, worth checking. Sort of tricky to read, but the best one I've seen:
[image] [/image]
Last edited by Tony2005; 12/07/05 04:05 AM.
"Always do the cheap and easy ones first."
1996 V6 ATX 96K miles
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Clarification
Originally posted by Tony2005:
Wastefire? Here is a diagram post by Favorite Mystaque which should explain the Spark Plug 2 - Injector 6 connection.
Coil 1 on the Coil Pack is for Spark Plugs 1 and 5
Coil 2 ............Spark Plugs 4 and 3
Coil 3 ............Spark Plugs 2 and 6
"Always do the cheap and easy ones first."
1996 V6 ATX 96K miles
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Wouldn't a power balance test tell you exactly which cylinder(s) is misfiring? Then once you know the cylinder(s), you can narrow your testing to determine whether it's a fuel, compression, or spark issue.
You can do this test with a few lengths of electrical wire, a tachometer, and a grounded screw driver. You can probably find a tutorial on the web in case no one has written one in this forum.
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Originally posted by stuvx:
Wouldn't a power balance test tell you exactly which cylinder(s) is misfiring? Then once you know the cylinder(s), you can narrow your testing to determine whether it's a fuel, compression, or spark issue.
You can do this test with a few lengths of electrical wire, a tachometer, and a grounded screw driver. You can probably find a tutorial on the web in case no one has written one in this forum.
On an older car, yes, however, this Contour uses a coil for a pair of cylinders. Suspect in this case is the coil for cylinders 2 and 6, which fire at the same time. One cylinder will be on the power stroke, the other will be on the exhaust stroke (to burn any remaining unburned fuel) if I remember correctly. So, if you ground out that coil (which I don't recommend on computerized cars and transistor ignition) you still won't know which cylinder is misfiring, 2 or 6.
Depending on the year of the car, a high-end scan tool may have the capability to turn off one injector at a time. If the problem is truly injector #6, and it is easy to duplicate the misfire condition, this feature could certainly help out there. An up-to-date OTC Genisys scan tool has this ability, at least for a 1998 Taurus SHO.
-Rod
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