Engine Pinging
 

Hey, I Was Driving My 94 Aero 4.0 Today And Was Noticing The Engine Would Ping Under Load. I Had The Ac On And Had A Pretty Stiff Head Wind. Any Suggestions, Or Is This Normal With The 4.0.

Sounds like plugs and wires need replaced. Common problem with 4.0, especially if cheap wires were previously installed. Motorcraft OEM are the recommended brand. A little more costly but well worth the price in the long run. Same with plugs but Autolite or Bosch will work as well. Decarboning the engine will also prevent premature ignition ping and rattle. Search for 'Seafoam' or 'decarbon' on this forum.

I hope you have better luck than me and my '93 4.0. I tried all that. I even cleaned the MAF. The next thing would be for me to replace it. I have the exact same symptoms you describe.

Vango,
Here's a wild suggestion prompted by another thread I was reading last week. If you truly have tried all those things and still have a ping in your 4.0, raise the hood and check this. Look along the top of the firewall about midway for a "fiberboard pocket" looking affair with a small device stuffed into it and an electrical connector attached. (This the MAP sensor). Come back along the electrical harness about 4 inches and find another connector that just dangles from the harness. There should be a squarish-grey looking plug in this connector. If the plug is not there, you are missing the jumper for the SPOUT connector and your timing will be off as the spark advance profile is altered. This might be the cause of your pinging.

Don't worry about the TSB in following CD service info, Ford fought the knock/preignition for years in the 4L and gave up
pull the Octane Adjust Shorting bar aka plug to retard base timing to protect your engine until you find the cause
located in center of fire wall over engine in wiring loom 2 wire cable hanging out with removeable plug, on EDIS 4L's only. Ford says 3d timing retard, most measure 4-6d retard, just enough to stop most pinging
Ford also makes a combustion chamber cleaner, don't recall the name or part #, supposed to work very well-strong, must be similar to the GMC, OMC and Mercury combustion chamber cleaners

From Ford 4L Service CD PCED section

Octane Adjust Shorting Bar

The Octane Adjust (OCT ADJ) shorting bar (Figure 25) is used to retard spark timing. Removal of the shorting bar from the in-line connector will typically retard spark three degrees. The purpose of the OCT ADJ self-test is to check the state of the OCT ADJ shorting bar. A Diagnostic Trouble Code (DTC) will be present if the shorting bar is removed or if there is an open circuit. The OCT ADJ shorting bar is similar in shape to the SPOUT in-line connector. On some applications the PSP circuit will also have a similar shorting bar connector. DO NOT remove the shorting bar unless directed by a Technical Service Bulletin (TSB).

FG9 REMOVE OCT ADJ SHORTING BAR

l Remove OCT ADJ shorting bar only if there is a TSB authorization.

l Drive vehicle to verify spark knock.

l Is spark knock present?

Yes
GO to «FG10».

No
Testing complete. EEC system OK.