430 Another Misfire Issue

Hi Guys
So I took the car out for a spin last week after sitting a month or so and the engine light came on. At first I figured it was an o2 code from the aftermarket headers so I thought nothing of it. Yesterday I started it up and noticed it was not idling normal and it felt like it wasn't running on all 8. So I pulled the codes and saw a misfire cyl 7 with a standard obd reader. So I did the usual battery cycle to clear the ecm and see if that would get rid of it. No deal. So I pulled some covers and swapped the coils from 5 and 7. Still has a misfire. Then I pulled the plug on 7 and it appears fine (may try swapping plugs also). It may be from the crap fuel we have in the northeast so I went and got some redline fuel cleaner. Drove around for a bit (may need to drive more) but no change so far. I then connected the launch reader and got some odd codes. I was wondering if anyone had any ideas if these other codes could be the problem. Thanks Image Unavailable, Please Login Image Unavailable, Please Login
These came back after dtc clear was done
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My guess based on some of the codes you are getting could possibly be a battery issue ..

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I know that's always my first thought but the battery is only a year old and it's been on a ctek charger all the time.

 

I also forgot to mention that the engine light is flashing (most severe) while driving and solid when I come to a stop.

 

Did you check if you are getting spark or signal to ignition coil

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No. Not sure how to do that on this car. I have a spark tester but it doesn't seem to easy with the size of the coil pack. Is there another way to test it that i'm not aware of. Thanks

 

I just went through this with my 360. If you have an oscilloscope, a COP probe, and a current probe, you can check a lot of things in your engine. The current probe captures the ramp up in amps as the coil is charged and the COP probe catches the actual firing of the COP and the burn time of the spark plug. You don't have to have a lot of experience to find the cylinder that's misbehaving.

You can find the exact details of how to do this on YouTube. Pico has some good videos on their site as well. The cost of the oscilloscope and the probes is less than $1000, which you could easily spend if you brought your car to a mechanic.

p.s. I suggest you stop driving your car until you fix it.

 

Just curious what did your problem end up being?

 

Does your tester look like this

You can spray a little brake cleaner fluid near intake manifold near gasket and see if engine speed changes



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No its a spark plug with a clip. That's a bit more high tech. But I will check none the less. Thanks

 

So I tested for spark on several cyl and it appears fine. I also used a stethoscope to see if the injectors where clicking and they seem fine also. I went through every fuse and they are good also. My exhaust seems to be turning purple/blue all of the sudden which would usually indicate a lean condition. I also did the intake gasket check at idle with brake clean and no change in rpm. I'm a bit baffled at this point.

 

Did you do a load test on the battery?

 

No but it's an odyssey 1500 that's only a year old and it cranks over really fast. I'm starting to think it's a fuel issue like injector or pump.

 

Before you start fretting over things that are really expensive to fix, why not buy one COP and replace #7. That's the one throwing the code, that's the one you should look at. Using the old "it has spark, must be good" method may not work with COP's. There is so much that can go wrong and still show a spark. Besides, could you even tell if it was missing? Would be hard to tell without looking at a trace on a scope.

 

Change the plug. It's not possible to visually confirm that it is good.

 

I swapped the cop from 7 to 5 and vice versa. Still shows up as a 7 misfire. I can feel the miss at idle and when I had 7 cop off to check spark it still felt the same when running. It was like #7 made no difference. I was going to try pulling the connector while running but that would probably screw something up so didn't.

 

My next step was to swap the plugs between two cyl and see if the code moved with it. Normally I would just throw plugs in but This covid thing makes me not want to go into a parts store and shipping is two weeks out at this point.

 

I have seen bad plugs on my car. Very rare but it happens. Change the plug, it's $10.
Plug is dead leading to a non firing C7, which pushes unburnt gasoline and Oxygen in the exhaust, which causes the cat to burn hot, leading to blue color.

Don't drive it anymore until you figure this out. And when you have confirmed it's the plug, change all 8.

 

I am by no means as talented mechanically as most members on this forum but I thought I’d fill you in on something I experienced a while back on a Porsche 911. A very well know Porsche technician once had my car in for a misfire issue. He told me the codes were saying the suspected cylinder was fine but it in his opinion it was obviously not firing. He said he didn’t care what the computer said and that he knew better than that so he put his hand on the cylinder he suspected the coil was out on and it was cold. That’s how he knew it was that cylinder regardless of what the computer said. Now, I am not recommending you touch the cylinder while it’s running but maybe you could use a laser thermometer and see if there is a lower temperature than the other cylinders. I mean, I’d touch it, but I’m not recommending it. Haha!


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A laser thermometer pointed at the exhaust pipe right where C7 is does the same thing.

 

I do have a laser temp gun. The hard part is I have aftermarket headers and they are wrapped.

 

Let's us know how that goes

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So I swapped the plugs between 7 and 6 and the misfire moved to 6. Cant believe all that for a plug. Never had an ngk go bad on me but I guess it happens. yelcab you were correct these plugs do go bad. I guess I have to go to the parts store if they have them. Thanks guys I appreciate all the input and help. I will post how it runs when I'm done.

 

when i had my f430 missfire was caused by a bad upper intake gasket

 

That is why I suggested a little spray of brake cleaner on gasket and notice any change .. that is a common test for that ..mentioned a few times by others as well on other posts


I am so glad you figured it out

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