I got a 2005 4.2 V6. A few months ago I would be driving and all of a sudden I would accelerate and the engine would start shaking reaaally bad. The check engine light would come on. I pull over and turn the truck off, turn it back on and it would run fine. I took it to autozone and it pulled two codes: (P2106, P2135). I looked up the codes and found a few threads about changing out the TPS and having the dealer reflash the PCM.

I didnt have money at the time so I unplugged the battery and let it reset itself. Now, fastforward to two days ago, It did the same thing only this time a check engine light didnt come on. And now it seems to slip/stumble evertime I punch it a little. If I accelerate slow it doesnt seem to do it.

I went to autozone again and there were no codes. I know you cant really diagnose this over the computer but any help would be great I got a 200 mile drive this weekend. I also went to the Ford dealer to get a new TPS and they said I cant just get that part for my engine. I have to get the whole $470 Throttle body, which is ridiculous. I'm debating on whether to order one from Tasca.

 

5 Speed or Automatic transmission?

How old are the spark plugs?

is there a chance the fuel filter is partly clogged?

 

Automatic

48,000 on the stock plugs

Changed the fuel filter at 30,000

It seems to be doing it now basically whenever I accelerate. Sort of stumbling. But once i cruise it doesnt do it.

 

Can anyone tell me where the Throttle Position sensor is at on a 4.2. I just went to advance autoparts to get a new one and the one they had looked nothing like what Im seeing on my truck. Maybe I'm missing it?

 

Well I have been reading up all over the place about bucking and stumbling during acceleration (mostly V8's). And everyone says to change coils/wires/plugs. Is there anyway these have gone to hell with only 48,000 on a 4.2?

Sorry to keep asking questions and stuff. Im trying my best to not go to a mechanic or the dealer cause money is a factor. If I cant figure anything out there is a mechanic across the street from me that im gonna take it to.

 

Symptoms sure sound like a dirty fuel filter.

Cheap and easy to replace (with the line removal tool) so you might as well rule that out before you start spending serious money on it.

BTW, if you ran your fuel tank empty or very low, that can contribute to the filter getting clogged with sediment from the bottom of your tank.

 

I am known to run my fuel tank till real empty. Which is kinda ironic cause the tank before last I filled up 24.4 gallons in my 26 gallon tank. And the problems began again after this. hmmmmmm. Another thing to check tomorrow. Thanks Dave.

 

Running the tank that low can also lead to premature fuel pump failure from overheating - it needs fuel in the tank to keep it cool.

If you don't have any codes, the throttle body and TPS are probably okay, but the throttle body might be dirty. I'd pull it and clean it, and also clean the MAF. All that will cost you is some time, a can of TB cleaner, and a can of MAF cleaner.

 

I already cleaned both the TB and the MAF. And I just changed the fuel filter. Still happening. Im gonna go ahead and change all the spark plugs. If this does nothing I'm just gonna man up and go to the dealer.

 

I'll cross my fingers for you that it is simply a bad plug. They should last more than 48,000, but a bad plug could cause the symptoms and not throw a code.

As glc points out, your fuel pump may be weak and prematurely failing due to overheating regularly. Just another thing to consider.

 

Get a Haynes Manual too. Those things are awesome.

 

I actually had one but have no idea where it went.

Update:

Alllllright. Changed the plugs. All looked burnt but didnt look severe. Of course I've never done plugs before so I dont really know. Replaced them with Motorcraft plugs. I've driven about 35-40 miles and it seems to be alright for now. We'll have to see how it does tomorrow. Thanks for all the help so far. Really hope I dont have to ask anymore questions :o

As for the fuel pump burning out. I've never run it empty. And usually dont have to put more than 22-23 gallons in it when I fill up.

 

That's still lower than you should make it a habit of getting. For long fuel pump life, try not to let it get below 1/4.

 

Alright. I'll have to be on top of that. Guess I shouldnt wait for the light indicator. haha.