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Kr Losing Power


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I think the car has this problem for a while but I wasn't for sure at first. I first noticed it at highway speeds. It would shutter a little while cruising at highway speeds. I also noticed that I would have to give it a little more throttle to make up the mountains.

There was a time that I had to be careful because it would smoke the tires if I floored it in 2nd or 3rd. Well yesterday it couldn't do it in first. I was rolling around 10mph floored it and it took off, but didn't have the power to cut the tires lose.

Now I feel the shutter while driving though the neighborhood.

 

It still sounds the same and no warning lights. Any ideas? A tune up? Fresh plugs, fuel filter,,,,,,

 

Nothing done to the engine since it had 2,000 miles on it. New clutch around 20,000 miles. Almost 40,000 miles now.

Edited by sheppd01
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Maybe bad fuel? Did you just fill it up recently? Also, you don't think a fuel line is pinched or the fuel filter is clogged? You know it's getting air, so that just leaves fuel and spark. GL and keep us posted.

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sounds like something our 07 Expedition did...5.4 motor...had to have the plugs and wires changed....cleared it right up...good luck

Funny you say that. I had to do the same thing with my 07 Expedition at 45,000 miles. I was lucky in that the warranty covered it. Not sure why as I consider that a maintenance item. Have not had a shutter issue in over 17,000 miles.

 

Shepp, hope you resolve your issue.

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I haven't touched the KR yet but I plan on changing the plugs, fuel filter and all the fluids before I start it again.

 

Maybe this weekend..

 

On a probably related note. Wife just got her car back from the dealer; 7,000 misfires on two cylinders.

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I was leaning towards fuel filter too but with misfires on 2 cylinders, spark plugs would be the first thing I'd change.

 

 

Phill

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Plugs and fuel filter would be my advice. Fuel filter is supposed to be done every 15,000 I think. Not too hard to do either, just have to remove part of the driver's side plastic cover under the door and it comes right off.

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  • 3 weeks later...

From the beginning, i was thinking a plug coil. I had a coil go on the number one cylinder. Could it be possible to have two. On another note, summer heat will deplete the power on these cars...

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  • 3 months later...

I have changed the plugs, air-filter, and the mass airflow sensor. All the plugs where black except one. It was white. It runs better now but still is not at 100%.

 

You can see in the beginning of the video it back fires when I let off the gas. Last year it would make a cool rumble sound when letting off the gas but now it pops. What does that mean?

 

I didn't really notice until I watched the video but it sounds like it also pops when I was slowly giving it gas. Maybe I am being paranoid.

 

I was going to take it in to a very good tuner but he has had recent health problems so I am back to trying to figure this out on my own.

 

https://www.youtube.com/watch?v=6BuPpuz7QZk

Edited by sheppd01
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Do you know which cylinder the white plug came out of?

That would be a good place to start checking.

For those who are not aware, alway track which plug comes out of which cylinder.

A piece of cardboard with 2 rows of 4 holes poked in them and numbered lets you easily do that.

Also check the gaps on the plugs going in and coming out.

For modified/increased boost engines, to prevent misfires reduce spark gaps smaller than the oem factory settings.

For the cylinder that had the white plug, I would carefully check the coil pack and the injector to start with, along with their wiring and associated connectors.

Make sure they are fully seated and snap locked in place.

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While it seemed to run better and I hoped I had fixed it I was wrong.

 

It was getting 14 mpg highway and still didn't have all the power it should.

 

My best guess now is an injector or a valve problem.

 

Johnny Lightning has it now. He is going to start with a compression check and go from there.

 

The good news is if it is a valve problem I already have the wife talked into upgrading the cams. ?

 

Edit

I am not a mechanic but my best guess is that it had an injector that went bad and caused one of the cylinders to run lean. That was the reason for the one white spark plug and it may have also messed up the valves.

Edited by sheppd01
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