I never get the code in summer, no vac leaks, new injectors, 300,000 miles. will try DPFE but can 02 heaters be weak and not code? Thanks

 

I used to get the 171 and 174 codes only in cold weather and then they started coming back even in summer. so I did the isolator bolt chage and no codes yet with 200 mi. after the repair.

 

My DPTE rattles when i shake it. I doubt a new one rattles like that.

 

nope, just checked a new one i keep in the garage. no rattle.

 

cool thanks

 

Cold weather is when my 171/174 first showed up too, went down hill from there.
When it's cold the plenum isn't as soft as when it's warm, same thing for the isolator bolts. As it warms up they both become more pliable especially if you have the plastic plenum.
I could clear my codes and drive the snot out of it while it was warm and the didn't come back. Then in the morning when it went into closed loop (got warmed up) the cel would return.

Did the plenum gaskets and isolator bolts and it like a different truck.

Here is a good DIY for the job http://sites.google.com/site/fordf15...p0174fix/Home/
Have fun with the back bolts!!

 

Thanks for the tip. I'm saving it for winter when mine acts up. I'm going to see if the DPTE works first because it does sound like it is broken but I'm saving the instructions to a word doc in case. I will find out about those back bolts, but I have a full set of tools and have run across a few in my career as a BMW/Mercedes Tech that were a chore. The thing I did notice glancing through the excellent and very detailed instructions was a claw hammer. I cant count the number of claw hammers I chunked into a trash can that were a part of an aspiring trainee's tool set. Not judging...just made me chuckle. Thanks again, Rob

 

The claw hammer happens to be my most used daily tool.....but I'm a carpenter by trade!!! ha ha

You can wait till winter to do the bolts and gaskets--I kicked myself in the butt for not doing mine sooner though. It's SO SMOOTH now I can't believe it. And when you do get around to doing it be sure to clean the plenum real good-including the wells where the isolator bolts go.

Good luck and I had to chuckle at the claw hammer too!

 

My truck actually runs great. I get great gas mileage. It idles smooth and still gets up and goes when I kick it in the butt. The best Sixes I have ever drove. I have no symptoms other than the codes in the winter. It usually codes then only when my wife drives it on a cold morning. When I drive it it usually is fine, I think it's my two footed driving style, giving it a bit more than idle, jackrabbit starts etc. All this with over 290,000 miles. I do use synthetic oil though and have my own method of cleaning the injectors. I have had to replace the fuel pump once and a few batteries but nothing else except changing fluids and filters. knock on wood.

 

One other thing that might bring up those codes is the PCV where it goes into the t/b, I forgot to mention that earlier. It could also be climate sensitive.

There is an O-ring around it that gets hard just like the isolator bolts, might want to pull that and take a look. It is just 2 torx screws-real easy.

The down side is the PCV is dealer only at about 35 bucks, but I think you can find a GM distributor O-ring that will fit. As long as it is oil/fuel resistant you are good to go.

And while you're in there check the rubber hoses at both ends of the plastic stove pipe for the PCV, those rot/burn through and too can give those codes with out effecting the performance much.

There now you know everything I know!! ha ha
Good luck Jim