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Doc Hoy

Runs rough, Starts hard, slightly reduced power

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Been a while since I have visited the forum but I am at a loss.

 

Have 2012 TC with 200k. Gas engine automatic. About 5k miles ago, the truck presented the following symptoms. Starts a little hard. Sometimes has to turn over four or five revs before it catches. Other times starts a little easier. Runs rough at idle. Idles at about 800 rpm and sometimes feels as though it is ready to stall. Sound from the exhaust is of a misfire or staved for gas. I have to press the accelerator peddle pretty far before the truck accelerates. (As though the linkage had somehow slipped...but it hasn't) At speed the truck runs smooth but lacks power. 

 

Replaced coils and plugs. No help. Took to mechanic. He shot codes indicating bad coil. replaced coil. No help. Fuel pressure appears to be correct. No codes on injectors.

 

I have two of these trucks a 2011 and this 2012. Both have about 200k. 2011 runs fine. This one runs rough.

 

Any ideas?

Edited by Doc Hoy

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Any internal combustion engine ... only needs four things to run.

1)  fuel

2)  air

Fuel and air in the right ratio ... if there's not enough fuel, it'll be most noticeable in the upper rpm ranges ... and it'll run rough.  If there's not enough air, it will run okay up to the point there's no more air available, at which point it just won't go faster ... and it will run smoothly at that rpm.

3)  compression

This is the measurement of all thing mechanical.  If there's a loss of compression, then you have metal/seal failures in the cylinder/engine.  It's the most basic of diagnostic tests, and the one that nobody seems to do anymore.  You don't list it as having been checked, but it's what most of your symptoms point to. 

4)  timed ignition

Quite simply ... if you're losing spark, then the engine runs rough, spits back, back fires, etc.

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Compression is good. No water in the oil. No oil or water getting out of the engine. Doesn't run hot. Symptoms not perfectly consistent. By that I mean it does not always take five revs to get it to catch. Sometimes catches right away. Always runs rough but not always the same roughness.

 

I would take this to the Ford Dealership but I have very good reason not to trust them. I know of instances where they "easter egged" for repairs and then charged for everything that was done, even the things that DID NOT have an impact on the problem. I know that they do a bait-and-switch process. 

 

I was hoping that someone on the forum might have had the same or similar problem and could tell me what they did.

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How’s the cam belt? (if equipped)

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Have you Removed the O2 sensor and taken a pressure reading , If the converter is starting to plug it will give you a similar condition.

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7 hours ago, Mike Chell said:

Any internal combustion engine ... only needs four things to run.

 

 

A shop teacher used to say about engines, "suck, bang, and blow".

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suck, squeeze, bang, blow.

I am not doubting ... but what were the numbers on the compression test?

 

Fuel pressure can be "correct" for idle but still not keeping up with use.  Bad fuel filter ... or bad fuel.

 

To justify my questions and suggestions ... I teach people how to work on motorcycle and outboard engines.  Been doing so for 21 years.

1)  Air

2)  Fuel

3)  Compression

4)  Timed ignition.

 

You're engine's not running well, one of those four items is incorrect.  If you've fully verified the mechanical operation (airflow and compression), then the problem must be electronic (fuel delivery and timed ignition).

 

 

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To MRTN,

 

Thanks. I think I have pretty much confirmed the engine has a timing chain.

 

To GBL,

 

Thanks. No, I haven't. In fact I want to replace the O2 sensors but wasn't able to learn their location.

 

To fifty150,

 

Thanks. My shop teacher wasn't that nice. He had some more specific things he would say to us.

 

To Mike,

 

Thanks again. Don't know the numbers on the compression test accept to say that they were consistent in the cylinders. (Mechanic's words were, "You don't have a bad cylinder.") As regards idle, the truck runs rough as though there were a misfire on a cylinder. As regards acceleration, it acts like a carburetor car with a bad accelerator pump or a leaky vacuum advance line.  Also, in my first response to you I mis-spoke. I reported that the truck "always runs rough." and that is not the case. I should have said it "always idles rough". At speed it smooths out but is slightly lacking in power.

Edited by Doc Hoy

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If the engine has normal compression and no mechanical noises  you should be able to find out what is going on.

Please let us know what you find.

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