Engine bogging down, any ideas why?

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Jan 26, 2016 | 01:44 PM

TomKattt

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Engine bogging down, any ideas why?

Hi all. I have a 2005 Expedition and it has a problem no one has been able to solve. It is intermittent. At low speeds, the engine will bog down for a few moments. It's not something we have been able to reproduce so we don't know what's going on.

I replaced spark plugs and coils, cleaned my fuel system and replaced the fuel filter. There are no engine codes. I put my real time scanner on it and watched air flow and manifold pressure, hoping to spot something amiss. No luck.

If FEELS to me that the car gets stuck in a high gear and is lugging. I feel that way because I can press on the accelerator and the car will downshift, or I can manually downshift, and the car drives normally. So it SEEMS like at 10 mph or so it has somehow gotten into 3rd (or overdrive ... hmmm.... maybe I will turn off the overdrive for a while and see if that has any impact. )

Anyway, it seems to do it mostly at low speeds, I can downshift and the car drives normally. It feels like the engine bogs down, loses power for a few moments.

I have taken it to 3 shops and no one has any idea what's wrong. I'm looking for suggestions. Thanks.

Jan 27, 2016 | 10:46 AM

alloro

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Quote:

Originally Posted by TomKattt

I have taken it to 3 shops and no one has any idea what's wrong.

General repair shops or transmission shops?

Jan 27, 2016 | 12:08 PM

TomKattt

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I took it to general repair shops. I do not think this is a transmission problem; rather it is more likely a problem with the systems that control the shift points, assuming I'm even guessing right about this being a shifting problem. The shop I had it in yesterday said the transmission is working fine.

Jan 27, 2016 | 12:35 PM

alloro

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Quote:

Originally Posted by TomKattt

rather it is more likely a problem with the systems that control the shift points, assuming I'm even guessing right about this being a shifting problem.

The tranny shop has the ability to read the transmission codes which are different than the OBD-II engine codes. Going to them will confirm or dismiss the tranny as being the problem. Guessing isn't going to help you.

Jan 27, 2016 | 02:56 PM

pdqford

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Quote:

Originally Posted by TomKattt

I put my real time scanner on it and watched air flow and manifold pressure, hoping to spot something amiss. No luck.

"05 is prolly Drive by Wire. Does it have a TPS or equivalent to watch with your real time scanner?

Feb 12, 2020 | 07:38 PM

TomKattt

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Quote:

Originally Posted by alloro

General repair shops or transmission shops?

Hi, I have taken the car to a general repair, the mechanic took a test drive and said he had no idea what was wrong. He suggested maybe it was shifting too early and said I might just have to wait for it to get worse to get it diagnosed.

I took it to a transmission shop. The mechanic test drove it, said maybe I should try the Throttle Position Sensor, which I replaced and did not fix the problem.
I took it to a dealer who had no interest in this, suggested I take it to Aamco.
So, 3 places and squat for answers.

Feb 13, 2020 | 12:23 AM

CathedralCub

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Quote:

Originally Posted by TomKattt

I have taken the car to a general repair, the mechanic took a test drive and said he had no idea what was wrong. He suggested maybe it was shifting too early and said I might just have to wait for it to get worse to get it diagnosed.

Okay so don't go to this mechanic.

Quote:

Originally Posted by TomKattt

I took it to a transmission shop. The mechanic test drove it, said maybe I should try the Throttle Position Sensor, which I replaced and did not fix the problem.

I'd plug in and look at telemetry to see if the PCM thinks the same thing about your throttle movement as you do.

Quote:

Originally Posted by TomKattt

I took it to a dealer who had no interest in this, suggested I take it to Aamco.

That's too bad. I've found a lot of dealers don't like to work the older stuff, it falls out of their wheelhouse and they don't have experience with it, and it ends up being a complicated repair that takes space. It's better they recognize it up front than burn you for a bunch of money and time and not be able to fix it.