I have a 1998 4.6 extended cab with flare side bed. The motor pings real bad.
It has new motorcraft plugs, good wires, just cleaned the maf sensor. Installed a new pcv valve and hose and evap hose. the hoses were changed due to some previous codes that were being thrown. It looks like the ecm was changed since it has a seperate sticker on the door jamb. any input?

 

Next to the MAF is the IAT sensor. Clean that and see if that helps. I replaced mine years ago because it really knocked when it got cold out. It was rather inexpensive and simple to change. Solved the problem for me.

 

Sounds like it needs a new knock sensor.Pretty common thing on every '97-'98 I've worked on.
Real PITA to change since it's under the intake.
JL

 

As JL suggests, good chance it is the knock sensor. A failed or faulty EGR valve can also shown similar symptoms. No code available ?

Dave

 

no codes are being thrown. i ordered the knock sensor today. do i need to remove the intake to change is?

 

Before jumping to the conclusion, I would check vacuum leak first, because it's simpler than replacing knock sensor. Connect a scanner and read fuel trim. If numbers are high, vac leak is suspected. Vac leak will make engine run hot and cause pinging without throwing codes. YOu can replace knock sensor after that.

 

I would sure check other things as mentioned first, EGR, IAT.....can really screw it up. When my IAT was bad I got no CEL....but A LOT of ping. Very well may be the knock sensor in the end, but that thing is a pain to get at if it's the same as a 4.6 in Mustang. I pulled the intake because I wanted to change it to an updated one any way ( aluminum coolent crossover).....this was on a car though. Not sure on your truck if you can get at it.

 

Intake MUST come off.
KS will rarely if ever light the MIL.
JL

 

Ok new knock sensor in, new air temp sensor. And still pings with 91 octane. I know the heads were resurfaced when I got the truck. Is it possible I need to run a different spark plug. I change the DPFE, for a different code. But also checked for vac leaks and found none. The erg was work as well

 

Is it only pinging under lighter load?

 

no just when it goes over 3k or when im towning.

 

Is there any thing else that effects the timing.

 

Not to hijack the thread but my 97 is doing the same thing. No CEL either. One differance that on 91 octane the pinging is mosty non existant. Beginning to think carbon buildup creating preignition.

 

With no codes set, the only thing that will cause pinging assuming it is not an internal engine issue is the EGR is opening.
This will advance the ignition timing and lean out the fuel.
Both these togather is a no no under load.
Check out the EGR control vacuum regulator for leaking or hanging up not allowing the EGR to close once it has opened and the vacuum lines are on proper.
Clean the vacuum regulator filter under the round cap.
Normally the PCM will detect an issue in this system and set a test failure code but you never know.
Good luck.

 

Had mine do the same thing. It did turn out simple plug wire was arching inside the head not a good connection mine has cop's and did it. But my wifes truck also did it and she has standard wires . Get the holes cleaned out. they will fill up with dirt and may not let you get a good connection. Maybe put some of the greasy stuff they make for plug fittings. Its cheap