I have a 97' 4.6 w/ FOU1 code. Would a minor vacuum leak be enough to cause detonation? Also how could I test the pressure in order to find out if I have a leak.

I have cleaned everything, throttle body, EGR ports and tunnel, MAF, and have replaced the DPFE sensor and my EGR valve. IAC and throttle position sensor are also new. It doesnt seem to be isolated to one bank or the other and only happens at or past 2300rpms under load (accelerating). My sig saysd I have a K&N CAI but that has since gone and I have reverted back to stock w/ GOTTS mod. It happens regardless of octane or tune level and I am completely out of ideas...

 

I had the same issue with my 07 f150 with 4.6. I ran my Edge evo on performance with premium fuel for a few months when it occured. went back to factory setting and after about 2000 miles back to factory the pinging quit i recently switched back to the performance setting because my fuel milage increased from average of 13.9 factory to 17.6 performance, and once again im pinging. I talked to a few of my buddies with programmers and also to my dad and they have all noticed it in there trucks ford, chevy and dodge. my conclusion is that the timing is advanced to far causing this to happen.

sorry for the long reply but it did take a few trips back on factory before the pinging quit

 

Have you hooked it up to a scanner to see of there are any dtc codes?

I don't think your box code of FOU1 has anything to do with this......

Have you tried to replace the spark plugs and wires?

Have you checked the rubber ninety behind the TB?

 

Sorry to say your post is probably not related to the OP's problem.

His sounds more of a mechanically induced wear issue and yours is the programmer.

I'm not going to offer any advice here cause your topic should be in chips and tuners.

 

I have not changed the PCV valve or the tubing connected to it. Would that really have that much of an effect that it would cause ping? I though that the PCV just helped the engine warm up. I'll pull it completely off and look at it to make sure. Spark plugs and wires have 20K or less on them, both motorcraft. My scanner says nothing of a DTC. For whats its worth my upstream O2 on bank 2 has 138K on it and bank one has about 60K. I was thinking about getting longtubes but I dont want to exacerbate any pre-existing lean condition.

 

Try doing a seafoam to it, change the plugs and try it then. Otherwise the only thing I'm coming up with right now is a coil pack has an intermittent problem??? Try replacing one at a time or swing for 2 new ones if you can afford it.

Jeff

 

And FYI I had a wire go bad in 10,000 miles once. Just one but the miss was pretty bad and really bad on rainy or even humid days. You can lightly mist your spark plug wires with water(make sure you get them in the rubbing spots) while it's running. Worked for me. I would try this first before buying coils.

Jeff