1994 Explorer Limited with Bad Ping

[pilotmatt94]

So I have a 1994 Ford Explorer Limited that has been pinging fairly regularly for the past few years (no pistons have been damaged yet. I've checked). I have pulled the shorting block, put premium gasoline in it, changed the backflow prevention sensor, de-carboned the engine, and tried every other trick in the book. The longest I can make it go away is about a month. I've started thinking that the camshaft position sensor could be the culprit, since it was changed a few years back. Any thoughts?

I greatly appreciate it!

 

[Turdle]

Hmmm.
Try a new fuel pump relay, and while you are looking there, check the connection lugs in the power box for corrosion--heat damage.

Also, you might want to pull the ECM and look the wiring board over real well for bad solder. There is a capacitor in the fuel pump circuit, on the ecm, which has been know to fail. Search for "ecm capacitor" and you might find the information.

 

[rickybobby]

Check the fuel pressure, i have seen a failing fuel pump cause detonation more than once

 

[pilotmatt94]

Fuel pump relay failed years ago and has been replaced, but it can't hurt to put another one in to see if it fixes the problem. I will definitely check the capacitor in the ECM as well as the fuel pump since both will be easier than checking the camshaft position sensor.

Thanks!

 

[IAmTodd]

Have you cleaned your MAF? Mine was way down on power and pinging and cleaning the MAF restored it to normal.

 

[pilotmatt94]

Yep. MAF gets cleaned fairly regularly, in fact. That's part of the reason why im stumped.

 

[92exp4x4]

Vacuum leaks. I resealed the lower intake manifold and replaced the intake tube on my dad's '93. It made a world of difference. The truck has its original engine with 235,000 on it now. It just started having issues again nearly 3 years later, and we switched to premium fuel to fix it. So far, so good.

Check the intake and vacuum lines. Spray a little brake clean on the gaskets and listen for an increase in RPM. Also the intake bolts can loosen causing air leaks. I would check fuel pressure as well. I think it should be around 40 PSI. For some reason the mixture is leaning out and the computer can't compensate. You may be having EGR problems as well. Are the O2 sensors in good shape? I would assume you would get a code for them or your cam sensor.

 

[pilotmatt94]

O2 sensors are fine. I would get a computer code if I had issues with those. They have been changed and checked fairly recently.
I guess I should clarify why I am beginning to suspect the cam sensor. It was changed a few years ago, and immediately after the sensor was changed, the engine had a noticeable loss of power and gas milage.

 

[92exp4x4]

It could have been timed wrong. There is specific timing procedure for installing a cam sensor. I have the info somwhere, i'll look for it and post it.

I have done three of them, I should know by now.

 

[pilotmatt94]

Okay that's sort of why I was suspecting it. Thanks!