Engine Power Is Reduced - Ongoing Issue, Updates throughout thread.

[Mighty Hd]

Maybe check the fuse box, pull it off and see if there is any corroded pins.

Did that this morning. Everything looks good.

 

[Mighty Hd]

Well, the saga continues.

I replaced the terminal ends of the negative ground cable from the battery to the block/front bumper and discovered the inside of the cable was black and had a green dusty substance as well.

Installed the new battery to block/frame ground today. Frame grounding points are clean. The secondary ground at this same location looked good, but i went ahead and put a new terminal end on it as well.

I also re-did the ground wire under the driver side door; removed the end and spliced in a new loop terminal.

Everything was good, let it run and all the codes were gone with the exception of the transfer case.

After a hot -soak and restart, “engine power is reduced” message is back again.

FML.

Removed the top cover of the dash and verified the ground wires were clean and secure.

So the following has been performed:
Throttle Body (new OEM)
Negative Battery cable (OEM)
Battery is good
Every ground checked, cleaned and reassembled.
No evidence of wire damage
Fuses / relays all pulled and verified there is no corrosion


WHAT am I missing?

I’m half temped to either take it to the dealer or just sell the damn thing.

 

[Geotrash]

Well, the saga continues.

I replaced the terminal ends of the negative ground cable from the battery to the block/front bumper and discovered the inside of the cable was black and had a green dusty substance as well.

Installed the new battery to block/frame ground today. Frame grounding points are clean. The secondary ground at this same location looked good, but i went ahead and put a new terminal end on it as well.

I also re-did the ground wire under the driver side door; removed the end and spliced in a new loop terminal.

Everything was good, let it run and all the codes were gone with the exception of the transfer case.

After a hot -soak and restart, “engine power is reduced” message is back again.

FML.

Removed the top cover of the dash and verified the ground wires were clean and secure.

So the following has been performed:
Throttle Body (new OEM)
Negative Battery cable (OEM)
Battery is good
Every ground checked, cleaned and reassembled.
No evidence of wire damage
Fuses / relays all pulled and verified there is no corrosion


WHAT am I missing?

I’m half temped to either take it to the dealer or just sell the damn thing.

Is your battery an AGM? I just went through a whole series of electrical gremlins on my Infiniti G35X, which had a 10 month old AGM battery from Advanced Auto. Took it to them for testing and it all tested fine on their 1990s tech battery/charging system tester so they wouldn't replace the battery. Just the same, I went down the street to Autozone and bought a new conventional lead-acid battery and put it in. All problems magically fixed themselves.

 

[Foggy]

If your negative cable had the green corrosion inside of it, then that ground is no good
You can order online (RA) a new assembly - gm part - I did both of mine just
as maint when I did my headers/etc

 

[Mighty Hd]

New negative battery cable is on
Positive cable is good and cleaned
New 170 amp mega fuse
Ground terminal ends have all been replaced, crimped and heat shrink sealed:
- LT / RT front frame rails behind the bumper
- LT under driver door
- LT rear at the rear body mount
New OEM ground strap LT engine head to firewall

New throttle body
New gas pedal
New mass air flow sensor
New MAP Sensor

Removed all wiring from the wire loom, no wires are damaged. New wire loom
Dielectric grease on the PCM connection, throttle body connection, MAF connection and all ground points.

Removed the Blackbear tune and reprogrammed the factory engine / trans tune.

Still getting “Engine Power is Reduced”
Obviously with the factory tune I can’t drive it so I put the Blackbear tune back on, which prevents it from fully going into limp mode.

It happens only after a hot soak. Ie: Driven for 5-10 miles, full warm up. Sit for an hour or so and restart. Triggers a ton of codes and engine power is reduced. It was initially intermittent. Now it is much more frequent.

My next two options are to either trade it or take it to the dealer and fix it. Real ******* as I just redid the entire brake system and put new tires on within the last 5,000 miles.

 

[Mighty Hd]

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[Mighty Hd]

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[Mighty Hd]

Last set

 

[Just Fishing]

What happens if you do the heat soak repro with the hood open?

Might be a way to start blaming the ecm since it's under the hood.

 

[Mighty Hd]

What happens if you do the heat soak repro with the hood open?

Might be a way to start blaming the ecm since it's under the hood.

We have had some cooler weather, it is not doing it nearly as frequently. Specifically when it’s cold – cold for Florida under 60° – it will do it every few days.

I put the factory tune back on the ECM and the TCM end still getting the error. It comes up and says “engine power is reduced “and then disappears. No codes. However I’m getting a ton of fault codes. Nothing that illuminates the malfunction indicator lamp