Cylinder #7

[JZiegler]

I have been having problems with cylinder #7. I have changes the plugs. I have brand new coil packs. It still throwing a misfire code for cylinder #7. I have to get it inspected soon and I don't think it will pass with the engine light on! It is a 2000 Expedition XL. New battery, new alternator, new turn signal flasher. I know that last one may seem insignificant but when I changed it my odometer started staying on. Next I think I'll replace the Hazard flasher and see if my radio works on the buttons that don't respond!

Any suggestions on what else to try or do to resolve the cylinder 7 code would be greatly appreciated. Please do not say to take it to the shop. I don't trust most of them and book time is usually twice as long as it actually takes.

 

[Bedrck47]

Check the connector to the #7 COP Make sure the contact area is clean and tight.

If that doesn't help then take a ohm meter and check the wires from the connector back to the PCM

 

[JZiegler]

I had already checked the connectors and put water sealer (dielectric grease) to make sure it wasn't getting wet. I'll let you know about the wire readings.

Thanks

 

[East-TN]

COP bad?

 

[deweysmith]

Move a different coil to cylinder #7. If the coil is bad the misfire will follow it.

 

[docraymund]

Have your catalytic converter checked. Excessive backpressure can cause a misfire.

 

[JZiegler]

COP bad?

Did you read the part where I said NEW PLUGS AND NEW COIL PACKS AKA C O P?

 

[JZiegler]

Move a different coil to cylinder #7. If the coil is bad the misfire will follow it.

Misfire did not follow it is still #7

 

[JZiegler]

Have your catalytic converter checked. Excessive backpressure can cause a misfire.

Trying not to send it to the shop. OBD readout shows CC is good.

 

[1955moose]

Guys a couple of things. 1 a bad cat will not cause one cylinder to misfire, it would affect all under power, its like having a clogged vacuum cleaner and trying to clean your carpet, but instead of sucking its pushing, 2 even if his new coils were bad, he wouldn't get the same cylinder code, the odds would be 1 in eight or higher. No his issue is either as Bedrck 47 stated, he's got a harness continuity problem, an injector or cop/ spark plug that's misbehaving, or worse case scenario a bad valve/piston/ intake problem with #7. Appreciate all the help, but let's keep him focused on proper diagnosis, and repair of his problem

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[docraymund]

You could use a noid light and check the injector and cop terminal for pulsation. If both tests are good, check the connectors if they are loose. (If it wiggles slightly from side to side). You could slightly bend the tab for a tighter fit. If all these are ok, then you may need to do a cylinder compression test followed by a leakdown test. Good luck!

 

[Adieu]

Injector.


Switch it over with the next one and see if the miss follows


Iniectors are an easy 5 min affair, unbolt fuel rail pull up till the needed injectors clear the block, and click them out of their slots....just wear gloves and bring paper shoptowels as they'll drip a bit of fuel

 

[rjdelp7]

#7cyl is driver side and 3rd from front.

 

[JZiegler]

#7cyl is driver side and 3rd from front.

nope my #7 is drivers side and 2nd from the firewall!

 

[JZiegler]

I'm going to back up to first having problems. About 6 months ago, I drove through a Texas thunderstorm with "torrential" rain. It was bad enough that water was getting on top of my motor even though I was traveling at 85+ mph. My grandson needed me. I am his bestest GRANDMA (Oma). I am mechanically inclined, can rebuild most motors inside of 6 hours with all the parts at my side! Anyway, after this day, I started having numerous problems and was fixing them as they appeared. So, when my OBD II reader showed 3 misfires along with other problems, I fixed all the quick ones and left the misfires for a short time, I changed the front four plugs and was down to 2 misfires #4 & #7 I ordered a complete set of COP's because I had found on the plug change that my COP's in the back were coming apart, literally! When the packs came in, I replaced all 8 plugs, checked the connector gaskets, added dielectric grease to them, I replaced all 8 COP's and reassembled the vents and all the wires, hoses and crap under the hood that makes working on them a PITA! I test drove while running the OBD II coder and received #7 misfire. I believed it may just be build up in the cylinder so I drove it hard for a week. You know like a man, because I have a lead foot! The following weekend, I swapped the coil pack with the one beside it. Misfire stayed on #7. My connectors are tight, no water, no bad COP's, Motorcraft Plugs, just can't get rid of this stupid misfire and my inspection is now past due! So, I will be trying the noid light after my husband brings my car back tonight. He took it to work to test the wiring harness because my meter is missing.

Anything else you may think of...I'm checking aside from asking or stating things that may imply my lack of knowledge like where #7 is located!

PS The bad COP's #7 & #8 the connector (the end that looks like a plug wire, in case you don't think I would know) separated, the spring was stretched and broken on one, and the other was attached to the plug and stretched. Both boots came off the hard plastic body in pieces. I think #7 was dead before the storm and it just didn't throw a code until after. If so, would carbon build up take this long to clean up?

 

[1955moose]

Guys that the same thing, think about it! Either way you slice it, the winner is, drum roll please, #7

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[1955moose]

I apologize, didn't see female anywhere in your post. Was referring the guy in my posts. You didn't mention the torrential rain storm until now. You drowned everything under the hood, never a good thing. At this point I would pull both the #7 connector spray out with electrical cleaner, do the same with injector connector for that cylinder. As posted earlier, you've got water in one of those plugs, gotta be. Now you know why you don't buy a car/ truck with flood damage.

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[JZiegler]

I apologize, didn't see female anywhere in your post. Was referring the guy in my posts. You didn't mention the torrential rain storm until now. You drowned everything under the hood, never a good thing. At this point I would pull both the #7 connector spray out with electrical cleaner, do the same with injector connector for that cylinder. As posted earlier, you've got water in one of those plugs, gotta be. Now you know why you don't buy a car/ truck with flood damage.

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Ok, I have already done that to the connector, I'll do the injector tonight. I will also recheck all my plugs and replace any that are dirty in anyway. Even if it is overkill, you never know.

 

[1955moose]

On the spark plugs, try #7 first, since you keep getting that code, something involving #7 should be your solution.

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[mmurphy1313]

id guess injector.....but id rule out wires first, maybe even try seafoam or lucas product first before diggin in.
how many miles? which engine?