4cyl Engine Power Drops Randomly

For reference im the new owner of an 06 AC 4cyl manual, had the truck about 3 weeks now and started to have issues with power randomly cutting out while highway driving. Looking to see if this is a common issue.

scenario:
Cruising home from work @~70mph in 5th gear, suddenly engine power seems to drop as if fueling or electrical issue, during this brief moment the truck starts to slow significantly (engine still running) and giving it more gas delivers no engine response, seems to last for a few seconds only before returning to normal. I have a 20 mile commute to work and this just recently started happening but is occurring 2-3 times throughout my trip. The only way ive been able to resolve the issue safely is downshifting to 4th gear and giving throttle and it will respond.

other facts:
I generally keep the gas tank fairly full. I do not know the maintenance history of the truck as it was from a small dealership. Mileage is 162k. I can advise that the truck has a brand new frame (replaced last month), suspension, front brake calipers, and appears to have a new valve cover, intake manifold, and a few other underhood items.

Yesterday it threw a code P0456 (evap emissions *very small leak) according to my code reader but the conditions have been occurring prior to the code presenting itself.

was thinking of cleaning the throttle body, checking the vacuum lines, and using some vaseline on the gas cap gasket to see if these things help resolve the code and power drop issue.

thoughts?

 

Do you have the defroster OR air conditioner on when this happens? If so, try turning it off and seeing if it still occurs. The condenser can sap an awful lot of power from this little engine, and it's noticeable when it cycles.

 

Actually in most cases i have had the defroster on but on setting 1 or LOW. I can reevaluate that when i head out for work tomorrow, off today. Seems like that would not be the issue for me though as the defroster would be running constantly throughout my trip but the power dips seem to only last 3,5,10 seconds at most. And downshifting + applying power resolves the issue. It temporarily feels like i have NO throttle. Assuming it would be related to drive by wire at the pedal, tps, throttle body, or fueling, possibly vacuum leaks as the emissions code that presented itself yesterday may be related but uncertain of this. Other than these odd blips the truck runs smoothly, idles fine and does not have other driveability issues.

 

New development, my brake lights have been staying on supposedly due to a damaged grommet that presses on the switch but i had some time last night to fiddle with it and i found the switch to be loose in the mounting. I adjusted, tightened, and now the brake light issue has been resolved.

I read somewhere in another forum that someone suggested that a malfunctioning brake light switch may be communicating to the ECU or TPS to reduce throttle when the pedal is “pressed”.

in either case, the throttle cut problem was horrible driving home last night, must have happened about a dozen times but i noticed that releasing the gas and reapplying with the same pressure allowed me to work through the issue easily. Fixed the brake light switch when i got home. This morning on the way to work i had zero throttle blips. Abnormal given my experiences in the last week. CEL is still on with the same code as before. Nothing else has changed

 

How did a 2006 get a new frame in 2022? Isn't the cutoff like 12 years?

 

That's almost certainly what's happening, it's called brake override. Almost all vehicles with electronic throttle control have some form of it, whenever the PCM sees a brake signal input it will reduce engine power as a safety feature.
An EVAP code will not have any effect on engine performance whatsoever.

 

No idea on the new frame, dealer sisnt really five me a straight answer on wether it was comped or he had to foot the bill but based on their listed price i soubt he had to pay for to frame & replacement suspension components. All i know is ive been hawking the truck on the dealers lot for like a month, just before i went to pull the trigger on my trade, i noticed it was gone, then 2 weeks later it returned with the listed repairs. I ended up trading my H3 for it straight up, wasnt sure at first as the H3 was much nicer in the cabin and a lot bettoer offroad with 35”s and front/rear locking diffs, but i needed a truck and now that i have my taco, im enjoying it aside from this issue.

old whip:

 

Check all the simple stuff first, male sure air filter is clean check your spark plugs and all your grounds and make sure your battery terminals are tight and snug

 

definitely seems to be this. I’ve made several other trips without issue.

RESOLVED!