Flashing check engine light?

[TobyU]

Tried cleaning & securing connections to cops & injectors then revved up the engine idle until it started flashing again & the engine just really dropped on power & idle, something is badly wrong..I will definitely figure out a diagnosis plan tomorrow.

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Pull up that COP and see it if fires a plug consistently.

That is 1st step.

You can call me at shop number and I'll walk you though it... 937-964-5466
Toby


I have a 2000 1st gen here I have to get ready to sell, My wife's old one.

 

[TexEx]

Even one cyl misfiring will give you a flashing light.
#8 might be only prob.
You didn't accidentally drop #8 plug going in or lean the extension sideways too much to where it could have put pressure on the insulator and cracked it did you?...been there.
Check the wires first.
Then lift up the COP and put an old plug into it and start it up and see if it fires nice and hard and each time it should regularly with no skipping.

If so pull the plug and inspect or put another one in. They are cheap.

If not ignition and a solid miss on cyl it is time to do compression test and pull valve cover.

I thought about putting that ols plug back in just to check, you have to pull off the cpu board/mounting bracket to access the back cylinder at least its easier, I'll try in the morning, y3u may be on to something, thx!

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[TexEx]

Check the MAF. Make sure there are no bugs on it or its swelling from corrosion.

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Did that cple of weeks ago, cleaned with maf cleaner & throttle body throughly, thx

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[TexEx]

Pull up that COP and see it if fires a plug consistently.

That is 1st step.

You can call me at shop number and I'll walk you though it... 937-964-5466
Toby


I have a 2000 1st gen here I have to get ready to sell, My wife's old one.

Really appreciate that, do you mean pull it up & hover it over the plug tube? I'll buzz you tomorrow, thx

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[TexEx]

If you've been dealing with the slight misfire for a while, you could have a vacuum leak somewhere. Extra air entering the system that is not monitored is viewed as excess oxygen in the system and the ecu will compensate by adjusting fuel trims. Fuel trims in these trucks are key to understanding run issues. If you have an Android device, I highly recommend the Torque app. It's a one time $5 purchase. Then get a cheap $15 ELM OBD2 Bluetooth device off Amazon. It's been invaluable to me in figuring out my 5.4L both 2V and 3V.

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Elm 327? Just purchased thanks so much!

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[TobyU]

I thought about putting that ols plug back in just to check, you have to pull off the cpu board/mounting bracket to access the back cylinder at least its easier, I'll try in the morning, y3u may be on to something, thx!

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Yes. I always pull the CPU up out of the way to get to the rear one on pass side on 03 navi but that's #4.
Wait!
What year do you have?
On my 2000 no CPUs in the way anywhere.
Maybe you were thinking GM on cyl numbering and we're looking at wrong one.
Pass side is 1-2-3-4 and driver is 5-6-7-8.
When you said CPU mount it sounds like the 03 Navi but that it in the way of #4 pass side rear.
Did you get code P0308 cyl 8 misfire on a code reader ?
If so then we need to focus on #8 driver side rear one.
Could be simply bad COP on that one or unseated connector.

 

[John Stephan]

Elm 327? Just purchased thanks so much!

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Yeap.

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[John Stephan]

What about the COP pigtail connectors? Did any of the tabs break off and now are not securely held onto the coils? If you can disconnect them with the slightest tug without depressing the tab, this can cause a misfire as well.

If you find a broken tab, whatever you do, DO NOT ever cut and splice in a new pigtail. There is a much easier way. It takes finesse and practice.

Go to a junk yard, find a good donor truck, van, etc. Not every connector will be good. Cut them off and bring them home. Carefully learn how to depin the connectors, then replace as needed on your own vehicle.

The front couple cylinders are easy. I had to do #4. Many words were said, but eventually I got it done.


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[John Stephan]

I thought about putting that ols plug back in just to check, you have to pull off the cpu board/mounting bracket to access the back cylinder at least its easier, I'll try in the morning, y3u may be on to something, thx!

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There is such a thing as cheap knockoffs on the plugs. I bought a set of 8 from Amazon and they were all junk, the packaging was correct. I bought 8 good ones from the local AZ.



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[John Stephan]

Just to be clear. Cylinder numbering on a Ford is unique.

Front to back on passenger side on the V8 is 1-4. Front to back on driver side is 5-8.

I've seen you mention removing the ECU etc. to get to the back 2 cylinders. That is to access cylinders 3 & 4.

#8 is next to the firewall on the brake booster side. It can be accessed with extensions and not removing any accessories.

Make sure you dont have a bunch of water in the hole first. Use a blow gun to clear out any debris. Wife's expy had a hard miss #8 one day. Leaf debris on the cowl was allowing water to pass in a hard rain. It dripped down and filled up the plug well.

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