Do any of you know if they designed the Knock Sensor out of the 96 OBD II 5.0??
I have had an ongoing problem with detonation, so I am in the process of doing some long overdue work, one item of which was to replace my Knock Sensor. I have the upper intake off and everything out of the way, and I just cannot find the little sucker.

I bought a replacement Knock Sensor at Advance (listed part) but the sensor on my rig is nowhere to be found!! I gave up looking for the sensor and decided to try a different approach, and sure enough I found a threaded hole (oriented straight up) right behind the lower intake a couple of inches to the passenger side of center. I did a test fit of the replacement sensor and it seems to thread into the hole nicely.

Thinking that some bozo in time past might have just removed the sensor, I then searched high and low for a lonely, unused connector that was correct for the sensor. No such connector to be found!!

BigRed is a 96 XLT 5.0L OBD II. The computer has no stored codes, nor has it ever thrown a code related to a missing sensor. The detonation (ping) problem has developed over the last few weeks, so for several years there was not an issue. I always run 93 octane fuel, and I even retarded the timing to 8 degrees to try and eliminate the problem.

If any of you know the answer, or where I might find the answer, it would be much appreciated. I called the local Ford dealer and got the answer "If the part is listed in our computer as a replacement part, then it should be there"
which, to me, indicates they are not interested in looking into this further.

Thanks,

Tom

 

The generic listing of OBD-II codes that I have shows several knock-sensor-related codes that could be generated but the information I have covers all OBD-II Ford systems as of 1996 which would include the entire engine line not just the truck engines. Some must have had more than one knock sensor as some of the codes refer to sensor 1 or sensor 2. I would tend to doubt that the KS would have been suddenly eliminated from the system but its worth a look into by way of research. Wish I could be of more assistance. I'll see if I can dig up anything further.

 

Grey, I have spent a good portion of the day researching and crawling around under the hood. The threaded hole I mentioned is definately the typical location of the Knock Sensor. I dug through all of my manuals and found photos which confirmed the correct location. I can find no other possible location nor unused connectors in the engine compartment, having physically traced out every single cable and harness. The computer has never thrown any Knock Sensor related codes, as I mentioned earlier. I am pretty much stumped here, and not sure where to go next.
Any help is greatly appreciated.

Tom

 

My 96 developed the same problem at app 40k miles, especially when towing my 4000 trailer (only has 55k now original owner). I got rid of the ping by filling it with premium, pulling the negative cable on the battery and holding down the brake pedal for 20s (resets the computer) then hooking my trailer and let the computer relearn under full load. Can't say it did much for my milage but it stopped pinging and powers never been better.

 

Probably need to mention mine is 5.0/5spd and I've run premium ever since.

 

FWIW.....I think the use of a higher octane fuel alone would reduce or even stop the pinging. I know that removing the neg cable off the battery for a short while will reset the EEC to a base setting and it will re-learn all the parameters from that point, but I have never heard of pressing the brake pedal with the neg cable off......never ever.

 

As I said in my original post, I have always run 93 octane fuel. The PCM reset never resolved the problem, but that was not the issue here. Most Ford 5.0 engines have a Knock Sensor located in the block right behind the intake. The Knock Sensor detects the seismic vibrations caused by detonation, send a signal (changing voltage) to the PCM which then retards the timing until detonation stops. The majority of the time when a Ford 5.0L engine (5.8 also I think) suddenly develops a detonation problem, the Knock Sensor has gone the way of the Dodo.

My original issue in this thread was that when I went to replace the Knock Sensor, there simply was not one there. The threaded hole for it was there, but no sensor and no connector. I was trying to determine if the Knock Sensor was phased out when OBD II came on line in 96 with the 5.0 Engine.

I have since found out that the answer is a big YES (finally got my answer today). Ford designed the knock sensor out of the sensor package on the 96 5.0 Engine with MAF and OBD II. They decided that the monitoring systems in the OBD II program and the constant sensor input on engine conditions rendered the Knock Sensor obsolete.
The maintenance I had planned anyway when I removed the intake seems to have resolved the problem. I had tried all the usual tricks including a full tuneup (the works with top grade parts) and resetting the PCM, with no improvements.

With 130k on BigRed I decided to go all out, and replaced the fuel injectors (Accel 21lb), FPR (BBK adjustable), used Ford Racing 9mm wires instead of my usual Taylor 8mm, replaced my cork valve cover gaskets (leaking) with FelPro rubber gaskets, used my usual MSD cap and rotor, and trusty old Motorcraft spark plugs. Went ahead and replaced the MAF Sensor, as Ford has a TSB on lean driveability symptoms (pinging) related to the MAF Sensor (mine was factory original), and replaced my thin chrome valve covers with Ford Racing heavy gauge aluminum covers. I also installed an upper intake plenum spacer (1") to improve clearance and accessability and to provide better heat isolation to the upper intake. The only smoking gun I found was a pretty decent sized crack in the PCV grommet in my old valve covers, but as I had no other symptoms of a vacuum leak, that was an unlikely cause.

We will never know if any one of those components was causing my detonation problem, but the package definately seems to have corrected the problem. Not to mention the fact that BigRed purrs like a kitten and goes like a bat out of ...well, you know. So far it appears that I have not taken a hit in the fuel mileage department, will know for sure after a couple of tanks, I'll let you know. After a few days with no problems, I will take my base timing from 8 BTDC back to 10 and see how things go. If the detonation problem does not return, I expect another slight power boost from the timing change. I will let you guys know how things work out.

Tom

 

Well Streetgang, I owe most everything I know to the forums. The following is from the offroad-bigbronco faq:

13.5 The proper method to clear codes and reset sensors on an OBD-II equipped vehicle.

Disconnect the black ground terminal from the battery.
Depress the brake pedal for 20 seconds. (this erases the memory)
Re-attach the battery cable.
Drive the vehicle and prior to completing 5.7 miles come to a complete stop twice. After each stop perform a Wide Open Throttle acceleration.
Continue driving until you have completed 5.7 miles. (re-learning period)

Here's the linky: http://www.off-road.com/ford/bigbroncos/bbfaq.html

 

Well Steetgang, check out this quote:

13.5 The proper method to clear codes and reset sensors on an OBD-II equipped vehicle.

Disconnect the black ground terminal from the battery.
Depress the brake pedal for 20 seconds. (this erases the memory)
Re-attach the battery cable.
Drive the vehicle and prior to completing 5.7 miles come to a complete stop twice. After each stop perform a Wide Open Throttle acceleration.
Continue driving until you have completed 5.7 miles. (re-learning period)