The other day, my wife was driving down the highway in her 2002 F-150 when the RPM's just dropped, bottoms out then goes high, all in about 3 seconds. There was also a smell of something burning. Any Ideas? She siad it smelled like it was comming from the drivers side under the hood, I checked and couldn't find anything. So far it has happened three times.
Any assistance is appreciated.

 

Forgot to mention, engine is 5.4 and auto transmission with overdrive. She always keeps it in overdrive.

 

Has the truck had the cruise control recall done?

 

No, the recall hasn't been done but she never uses Cruise Control, could that effect it?

 

Sound like it could be an electrical problem. The recall is high priority. The truck could go up in flames turned off sitting in front of your house. Doesn't need to be on. Is it only the tach or do all the gauges dip down and rise.

 

Only the tach, it goes to zero then back up in about 3 seconds, loses power then it is fine but a burning smell. I couldn't find it, she says it is comming from under the hood on the driver's side

 

Update, she thinks it has something to do with the overdrive, she took it off OD and it doesn't do it. Is there anything havig to do with the OD that is on passenger side of engine compartment. I checked all fuses and relays and they all seem good.

 

I would go ahead and take it to the Ford and get that recall done. You might find out that your symtoms are all related to that despite the lack of you using cruise control. All of that wiring is intertwined. I would start there and see if that doesn't fix it

 

I made an appointment with the Ford dealer for the Recall and to scan the system. He doesn't think the recall will affect what is happening, one never knows though.

 

Had the recall done on the cruise control. The dealer took the truck for a test drive and the RPM's also dropped and returned to normal for him also but it happened so fast he couldn't tell what caused it. He thinks it might be a transmission problem.
I read some posts on here about the VSS causing something like that to happen with the speedometer. Could a bad VSS cause the RPM's to go down to zero, then all the way up and return to normal in 3 seconds? Could it be some other sensor? I am at my wits end here. The dealer checked for codes but found none.

 

well how bad is the power loss does the engine turn off or does it just get weak, what kind of smell like wires or gases, i would check all my fuses and make sure there are all of them are the right ones and make sure none are bad. there is a wire conecter on the back of the gage cluster. if it were lose it would cause the gages to fall but i haven't seen this cause a power loss. i think it could be posible thow. also your intake may need to be cleaned if so this would cause a power problem with a smell and proble a power loss.

 

The engine still runs, Power does drop though, it is just that the RPM's go to zero, then all the way up, then back to where they should be. The smell was like plastic burning. I checked all fuses and relays, they all seem good.

 

OK did the ford dealer unplug the sensor right next to the brake fluid resivior? if not unplug it asap, next look under the dash at all the wires make sure they are not cut and shorting out on each other. smell around the fuese box if you smell a burn like smell you better check it out. i would not recomend driving this pickup untill the problem is found and fixed. i would really follow the wires out of the dash and check them very good all the way out of the cab. also check them where they inter the cab and make sure the rubber has not been removed and the wires are rubbling the metal. good luck and once again this can cause a fire i would take the battery cables off.

 

The dealer took care of the recall problem, that wasn't related to this problem. They placed a recorder on the truck and we have to push the button each time it happens. We take the truck back to them on Monday morning, hopefully they will find something. I was hoping it was something simple like a VSS or crank sensor.