What's robbing my power?

[Boomer Vibe]

I got an '08 Vibe about 5 months ago and just turned over 8K miles. This issue has happened probably six or eight times. I will be cruising down the highway at a steady speed, and it will be like someone lightly steps on the brakes. After about 10 seconds, it seems like the power comes back to normal with a little surge. All of the AC, defrost, and fan controls were in the off position. I keep thinking that some load is cycling on, like the AC compressor, but with everything in the off position, it should not be cycling. When the AC is on and the compressor is cycling, I can never feel it.So if it is not the AC, could there be a cycling electrical load that would bog down the alternator? I was thinking possibly the electric cooling fan. I don't know what else would cycle on and off.I haven't even told the dealer yet because the problem is so intermittent. And there are no codes.Any ideas?? Thanks in advance for your input!!

[ou.grizzly]

Try taking it into the dealer; suspicions point to the ECU or Catalytic Converter. Have you noticed any change in fuel mileage?

[Boomer Vibe]

No big change in fuel mileage. Filled up today and averaged 31.2 for mostly highway driving.Can the dealer do any checks to confirm the cause without just starting to change parts?

[BlueCrush]

My first thought was the electric cooling fan as well, but I wouldn't think that it would need to be going on at highway speeds. Unless it was like 120°F or higher out.

[wyatt89]

Dragging caliper?

[Mavrik]

at cruising speed, the engine should have enough power that you shouldn't notice fans or a/c cycling on or not.Sounds like something else is going on.

[northvibe]

what year vibe, are you cruising with Cruise control or just with your foot on the pedal? GT or base model, etc etc.

[Boomer Vibe]

It has never been hot out when it has happened. It is really weird. The engine doesn't sputter or anything, it just looses power for a short time.

[Boomer Vibe]

08 base vibe fwd. It hasn't done it when the cruise is engaged. It's done it on flat ground as well as up and down hills. It has never done it just after the brake pedad was touched, so I doubt the caliper would be dragging.

[wyatt89]

Odd...it sounds like the a/c clutch is engaging...that's all I can think of...

[Digger]

I am going to say fuel pump or injector issue.

[northvibe]

so it never happens if you are using CC? so is it when you let off the gas? cruising can mean so many things soo thats why i ask. If this has never happened before then check your spark plugs, maybe fuel pressure, etc. but usually those if they were getting noticeably bad would throw a cel. hmmm you still under warranty? id bring it in, but be sure you can replicate it.

[Boomer Vibe]

It has never happened when the cruise control is on. I don't use the cruise very much. It has happened usually about 15 - 20 minutes after starting up the engine - going down the road 60-65mph. It has happened on flat ground, and going up and down hills. I am not accelerating or decelerating when it happens, just "cruising" at steady speed.I only have 8K miles on it. It has done it 6-8 times in the last 2K miles. I hesitate to take it to the dealer because it is so intermittent and I cannot replicate it. But I guess I will take it in. I was just wondering if anyone else out there has had the same or similar issue. Does anyone have access to all of the GM bulletins they send to dealers? I know they only let you know about recalls, not necessarily about other issues with the vehicle. I thought maybe there could be a bulletin on it.

[northvibe]

there is a tsb list some where on the site. So cruising you mean you have your pedal on the gas, but its lightly pressed so it says at a constant speed?Your year of vibe has a electronic throttle body, I swear there was a ecu flash or something for those cars with that but that could be 05's. You could drop by a dealer and ask if there are any ecu flashes available. Also you could try grounding the TB to your negative battery terminal, all electronic TB's can benefit from it and it doesnt hurt it. I just did that to my ms3.

[Boomer Vibe]

I will do a search for the tsb list. I'll also try a temporary ground wire on the TB. Easy to do.Cruising = constant speed (60-65 mph) with light pressure on the accelerator - not increasing or decreasing speed.I'll probably just stop into the dealer and TRY to explain it to one of the service advisors that don't know very much. Maybe if I'm lucky, I can talk to the service manager.Thanks for all the help!!