I have been pulling the fuel "relay" fuse on my 03 Expedition 4.6l. However, I've read that I only need to do that for the fuel pump fuse, not a fuse that has several systems on it, such as the fuel relay and others. In other words, I don't have a separate fuse just for the pump itself. Wondering if I do not need to pull the fuse at all.

The reason for the question - Im getting ready to do some datalogging w/the Xcal 2 and TP's instructions state that the PCM needs to be cleared between runs, which can be done by flashing the PCM or by removing the battery cable. If I am out on the road w/a laptop & friend, it would be alot easier and safer if I didn't have to crawl under the dash, pull the fuse, flash, replace the fuse. Rinse repeat.

So, again, on an 03 Exp w/ 4.6l and a fuel system type fuse, do I still need to pull it or can I jsut shut the vehicle down and flash the PCM without gymnastics!

Thanks,

John

 

I never pull mine.

 

Waterman

I think you are confusing two issues here. Removing the fuel pump relay is done to ensure when key is on engine is off and you are uploading a new program into your pcm that a leaking fuel injector doesn't start filling the cylinder with gas. Then when you restart.................kaboom! My understanding is that this is a very unlikely scenario, but possible.

Now for data logging you want to 'clear out' all adaptive tuning stratagies the pcm has created from your driving since uploading your last tune. For the best data you clear the pcm by disconnecting the battery (with the keys out of ignition), then reconnect, start and data log. This procedure gets you data only on the tuning before adaptive stratagy has a chance to change anything.

Now the by the way uploading a new tune to the pcm also clears out the pcm. Perhaps this is where the confusion lies.

For data logging you clear pcm, then log. Repeat for as many passes as you are doing on your particular tune.

I can tell you that the cab of the truck gets pretty full with laptop logging gear, wideband O2 logging gear, and passenger (cables running everywhere!).

good luck,


enb

 

I guess I am trying to figure out the instructions in TP's datalogging guide. It mentions that flashing the PCM w/ the Xcal2 will reset the PCM as well as doing the battery cable. If that is so, then it would be much easier to reflash than to do the cable. Then, I've read in other instructions, that if your truck has a specific fuse for the fuel pump, pull it. It "sort of" says (somewhere) that if you don't have a fuse just for the pump itself, then you don't have to pull the fuse.

I was just asking for clarification on the exact requirements for pulling the fuse - if I have a combo fuse, then do I still need to pull it? I've emailed TP to get clarification. Just thought I'd post here too to get other thoughts.

The search for perfection really is a long dusty road

John

 

fuel pump fuse should be under the hood, i know ive been guilty few times and didnt pull the fuse when i should but im getting into the habit.

 

my 03 EX manual shows an assortment of fuel related goodies - pump, relay and other things I don't remember at the moment, located in the fuse pannel in the passenger side kick pannel, which is what i have been pulling.

Maybe its different in an f150. I know the location of th pcm is different. When I was looking for the code sticker, TP was on the phone with me whilest I looked at the door pannel, then under the dash.... I reminded them that I thought it was in the engine compartment on the psgr side and they said, "Oh! an Expedition! yeah its in a different location from the 150!"

So I'm thinking that the fuel pump is on a combo circuit and as such doesn't really need to be pulled - but I'd really like to make sure

 

Unless there is a separate fuse, do not pull it (combo fuse).

They described my computer location and interface (3 wiring harnesses) to a T.

I reflashed my pcm w/out pulling the fuse and it worked fine.

I noticed that when I had done it before, pulling the combo fuse, it made a wierd buzzing sound at the fuse box. No noise this time. Doesn't seem any worse for the ware.

On to datalogging.....