Rough idle, running lean

2008 FORD F-250
135,000 MILES • 5.4L • V8 • 4WD • AUTOMATIC
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RIPKEND
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The truck is running very rough at idle. Has cut out at a stoplight. No issues at start up or while accelerating. Took it to a repair shop, and they indicated it was running lean. Relaxed coils and spark plugs. Ran a smoke test and indicated there was no leakage anywhere. Still the same issue is happening. They are now recommending replacing the engine entirely, which is a tall order. Any opinions on other possible solutions to this problem?
May 10, 2022 at 9:37 PM
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RIPKEND
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The previous comment was supposed to say replaced spark plugs and coils. Also, the repair shop also indicated the top of the engine is not getting oil.
May 10, 2022 at 9:45 PM
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KASEKENNY
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What is their reason for replacing the engine? The top of the engine is not getting oil.

How did they confirm this? If the top of the engine is not getting oil, then that would point to a pressure issue. So, what is the oil pressure?

https://www.2carpros.com/articles/high-or-low-engine-oil-pressure

Basically, I would need a lot more info in order to feel comfortable replacing the engine. Based on this info, it sounds like they are guessing with a large bill.

However, I suspect they have looked at all this but just didn't inform you. If the engine has oil pressure issues, then that could have damaged bearings. If that is the case, then the running rough issue doesn't matter.

So, let's address the proof that they have that the engine needs to be replaced and then we can make a better decision on what to do with the running rough. However, if the engine is running lean then that means you most likely have a vacuum leak somewhere.

https://youtu.be/4ktw1X4W_-k

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let me know about this engine issue and we can go from there.

Thanks
May 11, 2022 at 7:59 AM
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RIPKEND
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Thanks for the reply. I asked them after reading your reply. The oil pressure is low, and this has caused some scarring (I think that is the term they used) on some cam bearings. Is this more helpful information?
May 11, 2022 at 8:30 AM
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KASEKENNY
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It does. The scarring that they are talking about is on the cam bearing. It is actually called scoring, but they would have had to pull the cam bearings and inspect them in order to determine this. They would have had to have a reason to do this. Was the engine making noise, like rattling or knocking?

It just sounds a little odd unless there is more to the story. If there is not, then I would seek a second opinion before I go with what they guys are saying and replace the engine.

Let me know if there is more to this and we can go from there.
May 11, 2022 at 5:43 PM