Hesitation when accelerating intermittently

1994 LINCOLN TOWN CAR
174,518 MILES • 4.6L • V8 • 2WD • AUTOMATIC
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TOWNCAR FAN
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The engine hesitates when accelerating, but not all the time. No triggering factors except for acceleration and moving. Up, down hill, or flat does make it happen more or less times. Never happens at idle. Nothing shows up on the codes. I have replaced plugs, wires, cap rotor, injectors and EGR value. History: the car was a very well maintained limo in San Fransisco until I purchased it 1/4/2018. I was informed of the hesitation when I purchased it, but it has gotten must worse since then.
May 21, 2019 at 12:23 PM
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ASEMASTER6371
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Good afternoon,

Have you verified the fuel pressure? That is where I would start.

https://www.2carpros.com/articles/engine-hesitates

Low fuel pressure will cause this issue.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Also, the timing could be the issue if the chains, guides or tensioner are worn.

Roy
May 21, 2019 at 12:41 PM
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TOWNCAR FAN
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I know the fuel filter has been replaced, vacuum lines checked and the timing has been checked, but will double check the fuel pressure. FYI two mechanics have already tried to fix the problem. Thanks
May 21, 2019 at 1:37 PM
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ASEMASTER6371
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Okay, how did they verify timing?

What exactly did the two shops do for you?

Roy
May 21, 2019 at 2:05 PM
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TOWNCAR FAN
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I was not present but he said he did the plugs, wires, cap fuel filter, rotor, compression test and checked the codes and timing. He may or not have checked the fuel system, I don't recall. I did the injectors. The second one checked the codes and replaced the EGR value, R&R plenum to clean out EGR passage, cleaned throttle plates and performed KOER test.
May 21, 2019 at 2:25 PM
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TOWNCAR FAN
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Not sure how he did the timing.
May 21, 2019 at 2:26 PM
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ASEMASTER6371
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Without removing the front cover of the engine, there is no way to verify the chains.

Roy
May 21, 2019 at 2:50 PM
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TOWNCAR FAN
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Roger that...I doubt he did that.
May 21, 2019 at 3:06 PM
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ASEMASTER6371
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Okay, I would find someone else who will do a complete diagnostic for you to determine the issue.

Roy
May 21, 2019 at 3:10 PM
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TOWNCAR FAN
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I believe the second mechanic will be able to do that. I really only came to him regarding the EGV issue.

Thanks for all your advice!
Robert
May 21, 2019 at 3:17 PM
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ASEMASTER6371
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You are welcome.

always glad to help.

roy
May 21, 2019 at 3:24 PM