Jump to content
Ecoboost Owner Forums

Recommended Posts

Ok, so I have a LMS tune (4+) otherwise completely stock. Put some 100oct (unleaded fuel), and after about a quarter tank I got the MIL/DTC P0420 and P0430. Dilited the fuel with some 93 oct, but still, have a good deal of 100 oct left in it, and the light keeps coming back after I clear the codes.


So my question is regarding the Direct Injection Engines...are they really picky when it comes to fuel, or are both cats faulty on the my SHO (I find that hard to believe, but the F150 gues seems to be changing faulty cats all the time).


This has never happened to me with any other car, and i have used that 100 oct on multiple cars, however the Ecoboost might be a different animal. I will drive it like this and then fuel one whole tank of 93oct, reset it, and see what happens.


Any input is appreciated!

Link to comment
Share on other sites

I believe the tunes are specifically set up for the octane that you provide to the Rick. I could be talking out of my butt here but it would seem if you got a 93 octane tune, the engine would hate anything other than that 93 octane. Hopefully Rick can comment on this.

Link to comment
Share on other sites

LMS's tuner "recommends" running > 93 octane for the stage 4+ tune but they obviously have a ton of people running it successfully on 93 octane. (I would personally recommend scanning for Knock to make sure) Since you are positive it doesn't have lead in it (because that would be very bad for the cats) I would do as you suggested and run the existing gas down and then switch it back to 93, clear the codes and see what happens.


The cats could have died due to overheating or a major thermostat issue (which you probably would have noticed). I would assume the tune would still keep some safety limits in there for your cats. You can monitor cat temp with the SCT if you happen to have one.

Link to comment
Share on other sites

I've ran 100 octane many times in my car without issue. More so before the addition of methanol injection but even a few times since' date=' especially when I was track testing a new program just for security purposes. Which fuel was it?[/quote']


I used CAM2 fuel, which is identical to SUNOCO 260 GT UNLEADED RACING GASOLINE. Like I said, I used it many times in many different cars, and have never had an issue, until now. I am beginning to think that because it is a slower burning fuel, and maybe because the SHO cat system is so picky/efficient, it is throwing the codes - not sure though.

Link to comment
Share on other sites

P0420 - Bank 1

P0430 - Bank 2


Diagnostics/Causes: Same


According to Ford/PTS:


Possible Causes:


Use of leaded fuel;

Damaged heated oxygen sensor (HO2S);

Out of range engine coolant temp (ECT) sensor;

High fuel pressure;

Damaged exhaust manifold;

Damaged cat;

Oil contamination;

Cylinder misfire;

Downstream HO2S wires incorrectly connected;

Damaged exhaust system pipe;

Damaged muffler/tailpipe assm;

Retarded spark timing;

Leaking fuel injector


Hope you find something....



Link to comment
Share on other sites

Based on my observations with SCT Logging and my DASHHAWK, the cats in the EB Engines run much cooler temps than the ones in my 2 G8 GT's. So... if they got hot, they may as well have coded, and are continuing to code, if they are still running hot.

Could you possibly have damaged your wide band sensors?

Link to comment
Share on other sites

  • 8 months later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...