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Discussion Starter #1
Ok guys,

Here are the symptoms:

Misfire on Cylinder #6 code generated in CEL and car obviously has a miss in it when you run it.

Here is what I have done:

1. Pulled the plug... plug is brand new, and is wet with fuel, so getting fuel to the cylinder, so not injector.

2. Hooked Timing light up to verify spark being generated: Spark pattern is normal for ALL cylinders except for #6... has break in the spark pattern. (1-2-3-break-1-2-3-4, 1-2-break-4)

3. Swapped spark plug wires with #5 cylinder, (both plug and coil end) and still #6 misfire.

4. Put different coil pack on, and misfire still there on #6.

Any ideas?

I've got a spare EEC and was going to put it in later today to see if that is the issue.

Only thing else I can think of is bad crank sensor, or misaligned gear wheel inside the timing cover that does the timing on the crank?

Please help!!!
 

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The first thing I see is that your runinng NGK plugs. Plus you cannot always look at a plug and tell what condition it is in.

Grab a set of DP Autolite and try that on for size.
 

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have you messed with the trigger wheel behind the front cover?......if not, then I highly doubt that is your problem.....unless it cracked on its own, which is also highly unlikely

if you are running a non-stock maf and/or injectors I would not recommend swapping out the EEC...those are two things that absolutely have to be accounted for in the pcm for the car to run right
 

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Discussion Starter #4
running Bosch Platinum+4 Plugs and they are all brand new.

As far as the trigger wheel behind the timing cover, I had to remove it when I pulled the Oil pump, so it is a possibility that it could be out of position, but since it is keyed like the Pulley, etc, would be difficult to have it out of place.

As far as the EEC goes, if the stock one that I have is going bad, then for the short duration that I would have another EEC in place to see if THAT is the reason that the spark pattern is haywire on #6 should be negligible.

I just want to understand why #6 keeps missing so badly!
 

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running Bosch Platinum+4 Plugs and they are all brand new.

As far as the trigger wheel behind the timing cover, I had to remove it when I pulled the Oil pump, so it is a possibility that it could be out of position, but since it is keyed like the Pulley, etc, would be difficult to have it out of place.

As far as the EEC goes, if the stock one that I have is going bad, then for the short duration that I would have another EEC in place to see if THAT is the reason that the spark pattern is haywire on #6 should be negligible.

I just want to understand why #6 keeps missing so badly!
yea unless you cracked it, there's no way its in the wrong orientation

as far as the other pcm goes......if your currently installed maf and injectors are much different than stock, then the difference isn't negligible.....you likely have larger than stock injectors right? if so, you'll immediately be running the motor rich for a good deal of time...it's your call though
 

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Discussion Starter #6
To the best of my knowledge the injectors are stock (Yellow).

As for the other PCM I have stock MAF etc. On it at the moment and the other PCM is set up for my non-stock MAF and octane fuel.
 

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Discussion Starter #8
OK, other PCM didn't work, still have the misfire.

How many grounds are there on the Engine? Is it just the one on the Passenger's side, or is there another on the Driver's side
 

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You need to narrow it down to one particular thing. There are only a few things that would cause a misfire on one particular cylinder. It could be the plug, the wire, the coil, the injector, rarely the ECM, or something internal in the engine. Grounds, cam sensors, crank sensors and the MAF can not cause a misfire on a single cylinder.

So here is how you narrow this down. The coil should have cylinder 6 paired with cylinder 1, so just switch those 2 plug wires around at the coil. Since it is a waste spark system, it will still fire at the correct time, so this won't mess anything up. It probably isn't the coil because usually if a waste-spark coil goes bad it causes a misfire on both cylinders, however if there is a problem with that one side of the coil for some reason, after doing this your misfire will move to cylinder 1. Once you have done that, take the plug wire itself that is going to cylinder 6 and swap that with cylinder 7. Pull the spark plug out of cylinder 6 and swap that with 5, then pop the injector rail on that side up and swap the injectors between 6 and 8. Now clear the code, and drive the car until the light comes back on, and see which cylinder is misfiring. If cylinder 1 is misfiring, you have a bad coil pack. If 7, you need wires, if 5 you need plugs, if 8 you need an injector, if it is still 6, you have something wrong internally with your engine and a compression check is the next step. To do all of these things should take no more than 30 minutes, and it will give you a definitive answer of what the problem is without costing you a dime in parts.
 

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Discussion Starter #10
There are new plugs in all 8 cylinders, and still misfire.

I swapped a different coil pack in and still misfire.

I swapped plug wires between #5 and #6, still misfire.

The plug in #6 was wet, so I know the injector is operating.

Swapped ECM and still misfire

I put the timing light on plug wires 1-8 and get the funky pattern ONLY on #6 no matter what I did.

This is a spark problem based on all of my troubleshooting. I wouldn't think that a bad injector would cause such an errant spark pattern that I am seeing with the timing light.
 

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It's possible the injector is sticking opened. When you go to start it, does it crank for longer than normal? If so, you probably have an injector leaking and the fuel pressure is bleeding down. Does the misfire get better, worse, or stay the same as you rev the motor up? What is the timing light doing? Have you tried pulling the plug out and grounding it on the block and cranking the car over to see if you actually have spark at the plug?
 

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Discussion Starter #12
Haven't tried grounding the plug yet.

The timing light has a steady even pulse to every cylinder except #6. It has a quick succession of 3 pulses followed by a pause, then another quick group of pulses then another pause.

Starts up quickly.
 

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Have you tried swapping the plug wire to another cylinder? If it starts up quickly, then it is not an injector sticking opened.
 

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Discussion Starter #14
haven't had a problem with it starting. I've tried swapping plug wires between #5 and #6 (both swapping the entire wire from the coil pack to the spark plug, and just swapping the spark plug end)

It is going into Ford on Monday morning. I'm out of ideas, and I don't have all the computer stuff to see anything "real time". So for $93 I'm hoping they can tell me what stupid thing I did wrong...
 

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I would look into what cylinder fires before #6. The computer might be giving you a bad reading cause it thinks it #6 but there is really a problem with the cylinder that fires right before #6. Stay away from the Bosch Platinum +4 plugs. I've seen a lot of issue with them. Good luck, Brian.
 

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Discussion Starter #16
Turns out the issue was nothing more than just LOW... (30% low) compression in Cylinder #6.

LUCKILY the heads were under 3 year Warranty, so I got to pull it off, and swap it out for a new one.

With the new head in, everything is GOOD.
 

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Discussion Starter #18
NEVER in my WILDEST DREAMS... did I think that low compression would screw up a spark pattern! Bad ground, bad input signal, bad plug, bad coil, yes... bad compression... nope... learn something new every day
 

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You need to narrow it down to one particular thing. There are only a few things that would cause a misfire on one particular cylinder. It could be the plug, the wire, the coil, the injector, rarely the ECM, or something internal in the engine. Grounds, cam sensors, crank sensors and the MAF can not cause a misfire on a single cylinder.

So here is how you narrow this down. The coil should have cylinder 6 paired with cylinder 1, so just switch those 2 plug wires around at the coil. Since it is a waste spark system, it will still fire at the correct time, so this won't mess anything up. It probably isn't the coil because usually if a waste-spark coil goes bad it causes a misfire on both cylinders, however if there is a problem with that one side of the coil for some reason, after doing this your misfire will move to cylinder 1. Once you have done that, take the plug wire itself that is going to cylinder 6 and swap that with cylinder 7. Pull the spark plug out of cylinder 6 and swap that with 5, then pop the injector rail on that side up and swap the injectors between 6 and 8. Now clear the code, and drive the car until the light comes back on, and see which cylinder is misfiring. If cylinder 1 is misfiring, you have a bad coil pack. If 7, you need wires, if 5 you need plugs, if 8 you need an injector, if it is still 6, you have something wrong internally with your engine and a compression check is the next step. To do all of these things should take no more than 30 minutes, and it will give you a definitive answer of what the problem is without costing you a dime in parts.


I have the same type of issue, but with a mis fire in cylinder #8. I'm more of an SC guy and have not spent much time on my 97 LX at all. What would the order be for me to switch up the wire, plugs, injectors as stated in this post, but his issue was cylinder #6?

Thanks in advance.
 

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Cylinder 8 is paired with 2, so switch those 2 at the coil. As far as swapping everything else around, where you move things to is not important, as long as you note what components got swapped with what cylinders, and make sure to use a different cylinder for every component. The idea is that by shuffling the components around, if a particular component is causing the misfire, when you move that component to another cylinder, the misfire will move, and if you know where it moved to, and what component you swapped into that cylinder, you know what your problem is without spending any money on parts.
 
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