Vehicle loses power when driving uphill?

DEB58

MEMBER
2002 ISUZU TROOPER
3.5L
V6
4WD
AUTOMATIC
158,000 MILES

Owned since 2005. Three months ago, it started issues on steep grades, now slight grades also. Doesn't seem to have power, but down shift and it will make it up. Regular maintenance is always performed at a shop. Mechanics at the shop are stumped. Replaced EGR, timing belt tensioner.

Transmission shop has said 2 times in last 2 months, it is not transmission.

9 Replies

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Hi,

When you have a loss of power, it is usually either a fuel-related issue or a partially plugged catalytic converter. There are other things, but these are the most common.

So, by chance do you have a live data scan tool? If you do, let me know what the short-term fuel trims are at idle and the engine at operating temperature.

Also, let me know if any diagnostic trouble codes were retrieved and what they are.

If you haven't already, check the fuel pressure. Here is a link that explains how it's done:

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

You can eliminate the fuel pressure testing if you have the fuel trims.

If that checks good, then take a look through this link and let me know if anything mirrors what you are experiencing:

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

Let me know as much as you can.

Joe

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Tuesday, April 25th, 2023 AT 7:28 PM

DEB58

MEMBER
5 POSTS

Hi Joe, sorry about the delay in answering. No data reader, I am at the mercy of the automotive shop. I am trying to research it because they seem to be at a loss. My ABS light recently came on And I am waiting on an appointment to have the right front holding solenoid replaced, they said it was Code 40 on ABS dash light. This is only light that has been on, and code found.

The links you gave do not seem to match my uphill power loss. Okay on straight stretches, no power loss. Via my research I have asked them if it could be catalytic converters, clogged fuel injectors, MAS, RMS, etc, they say nope. So far, I've been told to get a new exhaust (terrible job from muffler shop, they cut it and welded new piece on, rather than whole section), new EGR, right rear wheel bearing, which has not fixed hill issue. I took it to another shop, he didn't get any codes, but lifted it and showed me the "new" muffler, which solved nothing. No one seems familiar with Isuzu here. Thanks again Joe.

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Thursday, April 27th, 2023 AT 9:36 AM

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Hi,

If they replaced the muffler only, that wouldn't remedy an issue with a plugged converter.

Also, since you notice power up hill, I suspect it is there when you are on a flat but not noticed because it doesn't require as much power.

The interesting thing about what you have been told related to the ABS, from what I see is that isn't a code for this year and model. See pic below. Maybe they made a mistake.

If you have a power loss on hills, there really aren't a ton of things that can cause it.

For example:

Timing'
In need of a tune-up
Plugged air filter
Converter restriction
Low fuel pressure
Transmission (was already checked)
Lack of ignition advance (PCM Controlled)
Faulty coolant temp sensor (causing issues with the air/fuel mixture)

I'm sure there are others, but that is the primary list. If you had a scan tool that had live data, I could walk you through testing things to see if there are any failing parts. Is there any way you could get your hands on one?

Let me know.

Joe

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Thursday, April 27th, 2023 AT 6:46 PM

DEB58

MEMBER
5 POSTS

I spoke with the shop on Friday. Mentioned there is no code 40. They looked up the record and it is code "43". I do not have access to a code reader, and the shop says that's the only code it throws. I will update you after they have it in this week. It sounds to me like the issues you mention should be remedied by the shop. I will update soon. Thank you again, Joe!

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Monday, May 1st, 2023 AT 4:45 AM

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Hi,

Code 43 is an ABS code. There is an issue with the electronic hydraulic control unit (EHCU). I don't feel this would cause you to have power issues.

As far as the other issue, let me know what they tell you. I'm interested in knowing.

Take care,

Joe

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Monday, May 1st, 2023 AT 7:47 PM

DEB58

MEMBER
5 POSTS

Hi Joe, not much of an update so far, still waiting on ABS. Pushed back to This Friday it is supposed to be fixed and reinstalled. I was led to believe it was a day/two, turns out not the case. I asked them to check the things you mentioned while waiting but I am getting nowhere. I may have to try to find another mechanic who will/can do a diagnostic. I'll try to keep you updated, but I can't get an answer out of them. I appreciate the help, I really do. Thanks again Joe.

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Thursday, May 11th, 2023 AT 6:29 AM

KEN L

MASTER CERTIFIED MECHANIC
47,536 POSTS

JACOBANDNICKOLAS is one of our best, please let us know what happens.

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Thursday, May 11th, 2023 AT 6:03 PM

DEB58

MEMBER
5 POSTS

Hi Joe. Well, ABS fixed, asked them to check list you mentioned, they didn't. Said it's fine on test drive down the block and back, and that's it for me. I now have an appointment with a new shop, Monday morning.
I can't get my hands on live data so that's out.
I did take myself on a drive 120 miles round trip, highway and gravel roads, out in the country. Drove fine. All straight stretches with smaller hills, no steep inclines. Ran good.
I then tried to do the grade heading the other way, and immediate loss of speed and power. So, it's definitely steep grades.
I will be asking a new shop to check the list you have mentioned. I will update you next week. Thanks again! Deb

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Thursday, May 18th, 2023 AT 12:02 PM

JACOBANDNICKOLAS

MECHANIC
109,724 POSTS

Deb,

Thanks for the update. Isn't it interesting how people know more than you by driving a vehicle around the block? LOL Regardless, something is causing the power loss to happen. I look forward to hearing what they find.

Let me know if you have other questions or if there is anything I can do to help.

Take care,

Joe

PS: Deb, at this point, I'm not certain what is causing this. I have no idea where you are located, but until the problem is resolved, I wouldn't drive in areas that may not be friendly. LOL Just be careful. We don't want it to stall on you and not restart.

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Friday, May 19th, 2023 AT 8:58 PM