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Discussion Starter #1
I know this isnt directly a mn12 question, but I'd appreciate the help. I've got a 93 CV LX, and it's missing like crazy. First things first, I pulled the plugs to see what they look like. Passenger side plugs are all just fine. The drivers side plugs were all sooty and black with carbon, so I've gone through plugs, wires, and an O2 sensor on that side. No change whatsoever.
It occurs to me that maybe the EEC is hanging the injectors open, but isn't it very odd it would hang open all 4 on one side all at the same time like that? Maybe a coil pack is going bad? I'm really confused what to try next, since most other things would affect both sides and not just one. The sooner I make this car driveable the sooner I can lay up my MN12 to install my PI cams, so I'd really like to get it fixed asap. Any ideas?
 

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It could have a bad exhaust leak on the passanger side causing the computer to think that the car is runing lean on that bank and it is trying to richen that bank up to fix the problem.
 

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These should go on the Misc.... Mod....????! Im with bird96, look into that!
 

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misc? It's a 4.6L question...




but the early 4.6l eec's were known for going out and messing up the fuel delivery, so it's a very good possibility. The coil packs dont individually control one side, both coil packs share sides.

-Thomas
 

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oh, but I did have a situation where my o2 sensor crapped out, I think I dropped it in tranny fluid during my tranny swap :( But that threw a code for that bank, and in turn told the computer to richen it up, when it was actually fine.
-Thomas
 

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Discussion Starter #8
It does have a very small exhaust leak after the cats, I'll get a new gasket and see if that helps. Somehow I doubt it, but its worth a shot. It had the leak before and never had a miss. The car never threw a MIL, and I did reset the EEC before restarting it with the new O2. I'll check it for codes, but I highly doubt I'll find anything. Keep in mind this car is an EEC-IV car. Whatever this is, i think it's going to be something odd. Thomas, I had the same thought about the coil packs but at this point I can't count anything out.
The timing is fine, as the front cover has never been off the car.
 

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Discussion Starter #9 (Edited)
Okay EEC-IV fanatics...
much to my surprise, I found a 172- system indicates lean (bank1). Then I blipped the throttle and it cycled the cylinders... performed the test three times, all with the same results. 1 2 1 2.
IMO, this makes no sense, since the right side looks perfect and runs well, while the left side looks sooty and runs like crap. what gives?

(Edit:) Pulled the plugs just because the tests made me curious. Pulled 5-8 and they looked the same. A bit rich and covered in carbon. Pulled 3-4 and they looked perfect. Pulled 1-2 and they look like they were in a coal mine - totally covered in soot.
I forgot to mention above that I did check the injector harness, and it's blinking and pulsing just like it should, so that's one culprit eliminated.
 

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Sounds like you may have a clogged cat on that side. Would explain the black plugs. The ECM may have also taken a dump, uncommon, but don't rule it out. Hope it's something simple, good luck Tom.
 

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Blown head gasket? Also, maybe the injector harness got a little too hot. I'd swap O2 sensors between sides and see if the situation changes.
 

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Here's some food for thought. Go back to your basics. The plugs are black and sooty. Why? Is the the soot wet or dry? Dry,sooty deposits mean you have a rich situation or a weak ignition. A weak ignition would also indicate a rich situation if the plug was not oil soaked. Your problem is occuring only on one bank. Why would the injecters work properly on one bank and not the other? Sounds like a weak ignition to me. Remember that your coils fire on the exhaust stroke as well as the power stroke of the paired cylinder. Visually check the inside of the towers of your coil packs to make sure that they show no signs of arching. This would cause a misfire of the opposing cylinder as well. You will loose throttle response and it will feel like a plug is fouled when you kick it down. It will look pitted at the bottom if it is. Let me know what you find out. Good luck!!
 

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Uncaged 94 said:
Here's some food for thought. Go back to your basics. The plugs are black and sooty. Why? Is the the soot wet or dry? Dry,sooty deposits mean you have a rich situation or a weak ignition. A weak ignition would also indicate a rich situation if the plug was not oil soaked. Your problem is occuring only on one bank. Why would the injecters work properly on one bank and not the other? Sounds like a weak ignition to me. Remember that your coils fire on the exhaust stroke as well as the power stroke of the paired cylinder. Visually check the inside of the towers of your coil packs to make sure that they show no signs of arching. This would cause a misfire of the opposing cylinder as well. You will loose throttle response and it will feel like a plug is fouled when you kick it down. It will look pitted at the bottom if it is. Let me know what you find out. Good luck!!
but the two ignition coils that power the 4.6 are not one coil for one bank. Each coil has 2 wires to bank 1 and 2 wires to bank 2
 

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Each coil pack is actually two coils. One for each set of matching cylinders. And they are on opposing banks of the engine. It is possable that the DIS module ( ignition module) could be at fault. It determines the turn on and firing time of the coils. You can check the coils by removing the plug wires from the towers and checking the resistance with an ohm meter. Be sure that you are checking the paired set. Resistance should be between 13-14 ohms. To check the primary resistance of the coil, pull the plug off of the coil and check the resistance. Put one lead between the center prong and one of the end prongs. Then switch to the other end prong while you are still on the center lead. Resistance should be between 8 and 9 ohms. Also check for battery voltage to the coils. check all connections to the coil from the DIS module. Make sure that the plugs are tight and corrossion free. If these check ok, it may be the DIS module, or possably the EEC module. Good Luck.
 

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ok, not that I am an expert or anything, but I wouldn't put it past the coil pacs. A local T-bird owner just went through the SAME problem. he changed plugs, wires, had everything tested...nothing: 2 weeks later he decided to try replacing the coil packs...viola! problem solved :D Just my .02

Shane
 

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So far the sound of a plugged up cat seems most logical. Having coil packs fail for one side of the engine(i presume this was an "out of the blue" occurance) would just seem a little far fetched to me. It's all possible, but what is most logical? That is, of course, my uneducated opinion. I hope you get it figured out.
 

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Thomas said:
misc? It's a 4.6L question...




but the early 4.6l eec's were known for going out and messing up the fuel delivery, so it's a very good possibility. The coil packs dont individually control one side, both coil packs share sides.

-Thomas
I'm with thomas on this one.............one coil packs controls 2 plugs on either side - so that rules out coils.


I agree it's probably the eec - they love to decide to hold x number of injectors open.

Go buy a NOID light from an auto parts store and check to see if they all blink or if those 4 are on all the time.
 
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