I purchased a 2001 Ford Taurus SE with the 3.0 12v V6 Vulcan, featuring sequential multi-point fuel injection and a returnless fuel system, last July.
From day one, I noticed slight detonation while running 87 octane. Some injector cleaner treatments and higher grade fuel eliminated the issue mostly, albeit it's progressively worsened. I'm now running 93 octane, and I persistently experience intermittent detonation. Eliminating:
-EGR valve (cleaned, but hardly dirty; not stuck)
-MAF sensor (cleaned and reading sufficiently)
-Vacuum leaks
-Exhaust leaks
-Failing PCV valve (new)
-Spark plugs (new)
-Wires (new)
-Ignition coil pack (firing all six cylinders strong)
and a couple alternatives that I do not recall, I'm bewildered.
1) She features a returnless fuel system. Bank 2 fuel rail incorporates a fuel pressure sensor; albeit it's disconnected from the wiring harness (the connector has been deleted from the wiring) and a feedback line to the EGR has been deleted as well. When I sought to read the fuel rail pressure with a scanner tool, the data stream for the sensor read 'not supported', suggesting that the PCM had been re programmed. Moreover, the fuel rail has a numeric identification, written in marker, much like that of standalone parts in scrap yards, but the former owner claims to have done any and all maintenance with the Ford dealership. Do returnless fuel systems not require a fuel rail pressure sensor in order to function, or to function properly, rather?
2) For the past two fill ups, when I reached a half tank, detonation was unbelievable. After topping off the tank and a couple minutes later, the detonation reduced and then ceased.
I put a flat-blade screwdriver to each of the injectors to conclude that they are all firing, and I have run some four injector cleaner treatments through the fuel tank since purchase of the vehicle. Moreover, I ran injector cleaner directly through the intake manifold into the cylinders to perhaps reduce the effect of carbon on increased compression.
I had access to a borescope recently, so I removed the spark plugs and inspected the pistons. Pistons in cylinders 4-6 are scorched (I did not attempt to view cylinders 1-3, as they are behind a mass of wiring harnesses and vacuum lines), and piston 6 has chunks blown of out it (I could not wholly see the other pistons due to their stroke when the motor was shut off). Curiously, the motor is experiencing little blowby.
Some time ago, the PCM threw P0174 (System Too Lean Bank 2) on two separate occasions while the motor was experiencing detonation. After increasing octane rating, I have yet to the see those codes thrown again.
I fear expensive repairs in the near future if the problem persists. Can anybody provide insight?
Thanks in advance!
**CORRECTION**
The fuel rail pressure sensor vacuum line Should conjoin with a vacuum line from atop the EGR at a rubber elbow into the back of the upper intake manifold, not to the EGR itself. Instead, the vacuum hose to the sensor has been deleted and the inlet port, plugged.
From day one, I noticed slight detonation while running 87 octane. Some injector cleaner treatments and higher grade fuel eliminated the issue mostly, albeit it's progressively worsened. I'm now running 93 octane, and I persistently experience intermittent detonation. Eliminating:
-EGR valve (cleaned, but hardly dirty; not stuck)
-MAF sensor (cleaned and reading sufficiently)
-Vacuum leaks
-Exhaust leaks
-Failing PCV valve (new)
-Spark plugs (new)
-Wires (new)
-Ignition coil pack (firing all six cylinders strong)
and a couple alternatives that I do not recall, I'm bewildered.
1) She features a returnless fuel system. Bank 2 fuel rail incorporates a fuel pressure sensor; albeit it's disconnected from the wiring harness (the connector has been deleted from the wiring) and a feedback line to the EGR has been deleted as well. When I sought to read the fuel rail pressure with a scanner tool, the data stream for the sensor read 'not supported', suggesting that the PCM had been re programmed. Moreover, the fuel rail has a numeric identification, written in marker, much like that of standalone parts in scrap yards, but the former owner claims to have done any and all maintenance with the Ford dealership. Do returnless fuel systems not require a fuel rail pressure sensor in order to function, or to function properly, rather?
2) For the past two fill ups, when I reached a half tank, detonation was unbelievable. After topping off the tank and a couple minutes later, the detonation reduced and then ceased.
I put a flat-blade screwdriver to each of the injectors to conclude that they are all firing, and I have run some four injector cleaner treatments through the fuel tank since purchase of the vehicle. Moreover, I ran injector cleaner directly through the intake manifold into the cylinders to perhaps reduce the effect of carbon on increased compression.
I had access to a borescope recently, so I removed the spark plugs and inspected the pistons. Pistons in cylinders 4-6 are scorched (I did not attempt to view cylinders 1-3, as they are behind a mass of wiring harnesses and vacuum lines), and piston 6 has chunks blown of out it (I could not wholly see the other pistons due to their stroke when the motor was shut off). Curiously, the motor is experiencing little blowby.
Some time ago, the PCM threw P0174 (System Too Lean Bank 2) on two separate occasions while the motor was experiencing detonation. After increasing octane rating, I have yet to the see those codes thrown again.
I fear expensive repairs in the near future if the problem persists. Can anybody provide insight?
Thanks in advance!
**CORRECTION**
The fuel rail pressure sensor vacuum line Should conjoin with a vacuum line from atop the EGR at a rubber elbow into the back of the upper intake manifold, not to the EGR itself. Instead, the vacuum hose to the sensor has been deleted and the inlet port, plugged.