Missing on cylinder 1

07Boss

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So earlier this week I start my 07 GT and head to work. About 20 mins later the engine seems to be lagging/sluggish feeling. I take the interstate most of the ride in. I was doing 60 with cruise control on when I noticed the engine lagging a little. Pulled into work, parked and the engine was running a little rough.
Time to go home, so I start it and the engine is running smooth. Within a few mins the engine was lagging/sluggish again and right before I get home, there's a check engine light. The code is a P0301. Cylinder 1 misfire detected. I pull the plug and it looks fouled. I clean it and put it back in. Start the car and everything seems fine again. I take it for test drive and it starts acting up again but the issue comes back then goes away again. I check the wiring to the coil on plug and fuel injector. Everything seems ok. I get a new plug for cylinder 1. Start the car and it seems happy again, running smooth. I think ok that the plug must have been the issue. Go to work the next morning and the lagging comes back. Check engine light comes on right before I get to work. It's good old P0301 again. So, I swap coil packs with another cylinder, no change. I pull the plug out with it attached to the coil pack and crank the motor. There's spark so that's working. I then pull the injector, use a 12-volt battery and I hear it click when I tap the wire on the battery.
I think the worst and rent a compression tester.
Results:
Cylinder 1 - 175
Cylinder 2 - 179
Cylinder 3 - 180
Cylinder 4 - 171
Thinking this is ok.

Now does anyone have an idea what to try next?

UPDATE:
I went and got a NOID test kit, both the fuel injector and coil pack showed they were working.

I'm out of ideas, any thoughts???
 
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crjackson

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Swap the injector to another cylinder just for the heck of it.

If no change, try the coil next.
 

Dino Dino Bambino

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Swap the injector to another cylinder just for the heck of it.

If no change, try the coil next.

Unfortunately he's already tried swapping coils to no avail.
He needs to clear the codes each time he swaps plugs, coils, or injectors with an adjacent cylinder and hope that a new code for that cylinder will pop up. It's extremely frustrating when one starts replacing parts and the problem either persists or goes away for a short time only to return again.
The problem could nevertheless be the no.1 coil pack (or at least ignition related since the old plug was fouled suggesting unburnt fuel) but the intermittent nature of the misfire makes it more difficult to diagnose. I'd suggest replacing the coil pack anyway if it's the original factory item and it's done over 100k miles (always use OEM replacements).
 

crjackson

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I had a similar problem on my 98 4.6 a few years back. It ended up being an injector that decided to be a "part-time-lover". It tested fine with NOID, but when I finally swapped them around, it eventually reveled itself. Once I was certain, I replaced them all and it's been fine for years.

I've also had the elusive COP heat issue. It was easy to verify by playing musical cylinders.

Hey, I took a shot! ;)
 

MasterofDisaster

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I had this sort of problem about 18mo ago. I was able to verify that the ignition was working and the injector was working. Mechanic smarter than I figured out it was a bad computer.
 

07 Boss

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Well now. What's up with the name bro? I'm the OG 07 Boss. How you gonna go around pretending to be me? Lol.
 

07Boss

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I had a similar problem on my 98 4.6 a few years back. It ended up being an injector that decided to be a "part-time-lover". It tested fine with NOID, but when I finally swapped them around, it eventually reveled itself. Once I was certain, I replaced them all and it's been fine for years.

I've also had the elusive COP heat issue. It was easy to verify by playing musical cylinders.

Hey, I took a shot! ;)
I played "musical cylinders", no luck. Still looking.
 

07Boss

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I had this sort of problem about 18mo ago. I was able to verify that the ignition was working and the injector was working. Mechanic smarter than I figured out it was a bad computer.
You are probably on to something, my SCT Tuner won't send files up or down since the misfire started. (Battery is at 12.5 Volts)
Going to run a smoke test just to see if there is a leak by cylinder 1. Doubt that's it since there isn't a lean DTC coming up.
 

VBSTANG06

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Sup 07Boss so you have swapped coil packs, got a fresh spark plug, and verified fuel injector is working. I would suggest taking a look under the valve cover and see if there is excessive play at the 3 roller followers for cylinder #1.
 

Dino Dino Bambino

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I would suggest taking a look under the valve cover and see if there is excessive play at the 3 roller followers for cylinder #1.
Good call. A bad cam follower won't cause a compression loss because the corresponding valve can still close properly, but it could cause a misfire because the valve can't fully open to fill the cylinder.
A cylinder balance test might be helpful.
 

07Boss

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Catch up time. One thing that may be important is this car has a CDC Shaker Hood System, I'll come back to that later.
So, I end up changing out fuel injectors and fire off the car. It runs great. No misfire or any other issues. For a short time, 1 day in fact, I was loving my car again.
The very next day I put my shaker back on and fire up the engine. My heart just sank, right away I can tell something is off.
It's got a misfire but it's not cylinder 1. Using the Noid test lights it turns out to be the #8 cylinder fuel injector wiring that is giving a weak intermittent flashing light.
Now, what I'm thinking is the Shaker Hood is also an engine cover besides a fresh air intake. The car is a 2007 so it's 17 years old. Is it causing more heat buildup since it covers over the Fuel Injectors and Coil Packs plus all the wiring for them?
Any ideas on methods to trace the wire for #8 cylinder injector so I can repair it?
See the stock photo of what it looks like below.

Shaker Pic.png
 

VBSTANG06

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That intake is nice it makes the 281 look huge ha. Possibly corrosion in the sockets for fuel injector plug I don't know how water tight that mod is. Make sure your ground wires have solid metal to metal contact. If you have an extraction tool for the injector plug wires you can pop them out and inspect and check the plug release tab as well I had 3 of those brittle tabs break off on me.
 

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