Evening gents! New here, not to mustangs though. This is my first 4.6 car, been good up until the last couple of months, been seeing code p1409 egr system circuit malfunction pop up, and go out a few times on it’s own. Symptoms include; after the engine is warm, and at highway speed, if I am at a very partial throttle, the engine bucks or jerks a little, like a hesitation or miss... Half or more throttle and it seems fine. Once I’m getting off the interstate and i need to let off the throttle to coast, the exhaust note can be heard ‘pulsing’ rather than a solid engine braking sound, and you can also feel that through the driveline slightly. Once I press in clutch and put her in neutral, the rpm’s will act eradic, dropping to as low as 400 and surging to 1000, hunting like that back and forth, the exhaust is also making the same ‘pulsing’ sound. Once stopped, typically the idle has stabilized, but as this get’s worse it seems to effect driveability anytime after this initial symptom shows up; especially at rpm’s below 2k. SUPER FRUSTRATING. As a first measure, I replaced egr regulator, to no avail. Then, removed and throughly cleaned egr valve and did what I could to test it with some vacuum, the diaphram appears to be fine. I’ve done that 3 times now, each time the symptoms and the code went away. I’m not really willing to fork over $180 for a motorcraft egr valve, so I ask... have you any ideas? I’ll admit, I haven’t tested a whole lot else, there are a few mods to the car such as:
Offroad H, catback, cold air, bbk TB etc. I have only really mesed with the idle stop screw a quarter turn or so just to keep the blade from sticking slightly and giving the feeling of a sticking gas pedal. Went with MIL eliminators when I did exhaust work, no other ideas as to what I could have done to stir up this mess. Any info or opinions greatly appreciated!
Offroad H, catback, cold air, bbk TB etc. I have only really mesed with the idle stop screw a quarter turn or so just to keep the blade from sticking slightly and giving the feeling of a sticking gas pedal. Went with MIL eliminators when I did exhaust work, no other ideas as to what I could have done to stir up this mess. Any info or opinions greatly appreciated!
