Ford Powerstroke Diesel Forum banner

Truck running too cold. P0128 code

7K views 7 replies 4 participants last post by  ZMANN 
#1 ·
I had a radiator leak on the stock radiator (truck has 100,000 miles) so I picked up a mitsumoto rad. When doing some reading about replacing the rad quite a few guys said I should replace the thermostats and hoses at the same time.

When I went to order everything mitsumoto had two options for thermostats, hotter or colder. I use my truck for towing 99% of the time and I thought that hotter would not be a good choice.

So I got all the new stuff on and refilled the truck with ford gold. Drove the truck to work and back every day this week and it was running good! I didn't have my logger plugged in so I don't know what temps I was seeing but it wasn't throwing codes and I did look at the temp gauge and everything was normal.

Last night it got down to 34 degrees or something and it was 42 degrees when I left for work. About half way to work the check engine light came on and I plugged in my logger. p0128. The temp gauge never went over 1/4 but the heat was working.

I got to work and checked the coolant level to make sure it wasn't low or anything and it was just over full. I cut a piece of cardboard and stuck it in front of the intercooler and set up my logger for temp. After about 10 mins it was up to 188-192. I drive back to work and popped the hood and I was able to put my fingers on the rad on the passenger side. The drivers side was hot though.

Do you guys think that maybe the new rad and the lower temp thermostats are just working too well? Or do I have one sticking open? I have a 700 mile trip that I'm towing my car to and have to leave for in 24 hours. I'll need to borrow a truck and smaller trailer if something is wrong. I really need some help...
 
See less See more
#2 ·
yeah- cooler 'stat... it'll do that.

... and the truth is the cooler stat does you more harm than good. it disallows the engine to reach the place it's scripted to trim fuel- and it's running richer than it needs to to prevent pre-detonation. On top of that, it's not going to keep an engine that is truly working hard any cooler...

but that aside, I wager it is stuck open. did you test it before you installed it?
 
#6 ·
Deisels and pre-detenotion ? not two words commonly used together

I would get my money back on the T-stats and order OEM

LINK is the cooling system diagram if your not familiar? you can see the two systems in one of the pictures and it may help you wrap your head around what may be going on?

http://www.backglass.org/duncan/ps64_manual/64L_cooling_system.pdf

and a over performing radiator will not cause your issues ( not that it is over cooling , I am just saying the thermostats are responsible for maintaining temps )
 
#7 ·
you don't think a diesel can ping? sure you do... you just messin' with me on a hung over saturday morning... lean is easier to ignite that rich- well, it's more unstable.... it takes less compression to make that happen. heat alone can cause it.. why for you make my aching head function you?
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top