DenisVeilleux

A lot of you talked about bad gazoline or bad plug gapping but did any of you got ODBII code PO300?

Just like most of you, I first tought about bad gaz so I filled up with 94 octane. When this wasn't enough, I gived it Octane additif, no change, still pinging and hard to start in the morning (but it start on ¼ turn rest of the day). Then, a friend asked if my brake pedal was hard to push before I started the engine first thing in the morning (it was) so, he said it might be a vacuum leak... A little search on the web came up with broken/damaged tubing going towards the PCV valve. I've checked all my hoses but can't find a leak.

Since I got PO300 (Random misfire) instead of PO301 – 308 (Which indicate the cylinder causing the problem) it leads me to believe in a vacuum problem instead of an electrical problem.

Is there an expert out there that has seen/experienced this before and can tell me what I can do to narrow it down before I have to go to the dealership? $$$$$

Thanks

Denis

DenisVeilleux

Just to keep you guys posted, I've taken my truck to the garage (good decent guy). He basically went through the same check that I did (which is the basic procedure for this type of problem) but, since he couldn't find anything, he went on to Ford Website (he must have a subscription cause I can't do it) and he found a service bulletin that mentionned (for the hard to start in the morning) one of the DTC code that could come up is the PO300 and it is frequently due to bad contact on fuse 27.

They recommanded to clean the contact and gived it a try. So he did and took it for a ride. He said that he could not hear the pinging anymore. As for the hard start in the morning, since he had spended a bit more than 2 hours on it he recommanded that I take it home and let him know if it fixed the problem the next morning. Guess what, it did; it started as I touched the key. He also told me that if it did not fixed the problem, the service bulletin recommanded to change the fuse contact (they have a kit for this).

As I wanted to find out a bit more info on that fuse 27, I did a search on the forum and YAK, it causes a lot of problems to many owner.

Hope it's gone help some of you.

Merry Christmas and Happy New Year

Denis

FLXLT

There is a relocation kit to move fuse 27 to #70 or 71 and use a fuse that's physically larger. Search fuse 27 and a bunch of threads with a part number and TSB information will come up.

Wouldn't be a bad idea to have the TSB performed to move the fuse.

DenisVeilleux

Thanks FLXLT,

I've already looked it up and will get soonest.