Reduced Power Mode

[sealandsky]

Hi brain trust - I has a strange thing happen to me a few hours ago... I had an opportunity to pass a slow car in front of me and being a short lived opportunity I mashed the pedal to the floor. Just as I was abreast of the car I was passing, I had a dramatic reduction in power to the point that it felt plike the auto-emer braking had kicked in. I managed to complete the pass (just barely), but had a message pop up telling me that I was now operating in reduced power mode. I also lost tow mode, cruise control and my Yukon drove like crap. I also ahd the traction control amber symbol showing. I'm guessing that I was running on around 50 HP. After getting home (25 miles) I shut down and unloaded my Yukon. Then I went back and started if back up and all was normal, drove great. Any ideas on this folks?

 

[swathdiver]

I mashed the pedal to the floor. Just as I was abreast of the car I was passing, I had a dramatic reduction in power...

How old is the battery and what was its start up state of charge?

 

[sealandsky]

How old is the battery and what was its start up state of charge?

It's an AC Delo "gold" and is 13 months old. Charge should have been fine and I had been driving on the freeway for about 3 hours straight prior to this happening.

 

[swathdiver]

It's an AC Delo "gold" and is 13 months old. Charge should have been fine and I had been driving on the freeway for about 3 hours straight prior to this happening.

The reason I ask is that we have seen engines cut out on full power runs because of a problem with the battery. Check grounds and connections on the cables and then consider having the battery load tested if the problem persists. If you have an advanced scan tool, the culprit will be identified pretty quickly.

 

[sealandsky]

The reason I ask is that we have seen engines cut out on full power runs because of a problem with the battery. Check grounds and connections on the cables and then consider having the battery load tested if the problem persists. If you have an advanced scan tool, the culprit will be identified pretty quickly.

I do not have a scan tool, but would you expect to see a fault code stored if I brought it to the dealer and had them check it?

 

[swathdiver]

I do not have a scan tool, but would you expect to see a fault code stored if I brought it to the dealer and had them check it?

Probably, along with a recording called "failure record" that shows what was going on at the time the code came up. These things clear after time if it passes so many self-tests.

 

[THarber]

Chances are it started knocking from fuel and timing so it pulled all the power out bny reducing timing. Run better gas and see if it does it again. I bought a tank load of crap 93 from a little gas station the other day and my truck is knocking like crazy.

 

[sealandsky]

Follow up: So, on the Monday following the Friday evening event I brought my Yukon to the dealer and they plugged in their scan tool and ran the diagnostic while I waited. They did not have a specific fault code from Friday, but did have several "low voltage" or "low power" faults stored. This does include my disconnecting and reconnecting the battery cable twice the previous week when I performed my 2X per year top engine cleaning. Since this single event everything has been perfect, so don't know what to think of it. As time allows I will check all of my power and ground connections just to be sure. Callaway also recommended this and asked that I let them know if it happens again. They were not familiar with the issues occurring on any of their vehicles.

 

[sealandsky]

Chances are it started knocking from fuel and timing so it pulled all the power out bny reducing timing. Run better gas and see if it does it again. I bought a tank load of crap 93 from a little gas station the other day and my truck is knocking like crazy.

I had fueled up about 100 miles earlier with 93 from a BP gas station I use often.

 

[sealandsky]

New recent event - 6 seconds of WOT, then highly sensitive throttle inputs and extreme surging if I even thought about increasing power. Drove 3 mile on the freeway, then took the exit and when I rolled up to the stop light the engine wound down and died. Re-start resulted in stumbling engine and if died. Same result over several tries. Finally got started and put in gear, drove a few blocks home and shut down. The net morning I disconnected the negative battery terminal, removed and cleaned the MAF sensor and reconnected. All runs perfectly now for two days. Did I fix the issue?

 

[Doubeleive]

fuel pressure?, throttle body, maf are things that come to mind for me, typically reduced power mode is a throttle body fault, but low fuel pressure could cause your symptoms as well and that is not something that comes up as any code you would need to check it and/or monitor it with a gauge.
you can get one of those bluetooth OBD adapters and run a app like torque that will allow you to monitor what the vehicle "says" it is.

 

[Geotrash]

New recent event - 6 seconds of WOT, then highly sensitive throttle inputs and extreme surging if I even thought about increasing power. Drove 3 mile on the freeway, then took the exit and when I rolled up to the stop light the engine wound down and died. Re-start resulted in stumbling engine and if died. Same result over several tries. Finally got started and put in gear, drove a few blocks home and shut down. The net morning I disconnected the negative battery terminal, removed and cleaned the MAF sensor and reconnected. All runs perfectly now for two days. Did I fix the issue?

My guess is you fixed it by re-securing the battery cable. The low voltage warnings were a useful clue.

 

[Rygrego]

My guess is you fixed it by re-securing the battery cable. The low voltage warnings were a useful clue.

+1.