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Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 35493
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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93 Ford Lightning pings under load when warm. I'm having a

Customer Question

93 Ford Lightning pings under load when warm. I'm having a terrible time trying to figure out the cause. Many parts have been replaced. Looking for ideas.
Submitted: 1 year ago.
Category: Ford
Customer: replied 1 year ago.
1) I checked the timing/balancer. Engine at TDC the balancer is right where it should be.
2) I pulled another plug and it also is clean with a bit of tan showing and some gray on the electrode. They are Motorcraft platinum plugs AGSF 32PM. Plugs and wires (Motorcraft) were replaced within the last year. Gap matches the hood decal spec.
3) Fuel filter was replaced in 2012. Not sure what mileage.
4) The truck came with some other parts in boxes that were already replaced. Throttle position sensor, EGR solenoid and EGR valve position sensor. The coolant temp sensor was also replaced probably around the same time (all within a year).
5) No discernible play in the distributor.Plugs replaced with Autolites. It's been months since I've driven it but it seems slightly better but still pings. All the platinum plugs I removed looked ok and weren't very old.Most recently I replaced with 'borrowed' parts the MAP sensor and ignition control module. Neither made any difference.
Expert:  Ron replied 1 year ago.
Hello, my name is ***** ***** I am a professional here at Just Answer. I have noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.
The problem you are describing can be caused by and of the following,
Excessive Engine Carbon — Excessive carbon in the combustion chamber.
Insufficient Engine Cooling
Ignition Timing
Incorrect Spark Plugs
If you are sure the spark plug are okay the base timing is set correctly then I would consider doing an intake induction cleaning and see if this resolves the problem you are having. See the steps in the link below, copy and paste the link to your browser to open and view them.
Customer: replied 1 year ago.
Thank you for the response. I will try this in a few days and report back!
Expert:  Ron replied 1 year ago.

Okay, Im here if you need me.

Customer: replied 1 year ago.
Ron, ran the cleaner through it today. Made smoke but drives the same after doing the road test - still pings with very little throttle application.
What baffles me is why it runs well with the SPOUT pulled and also when it is cold but under warm, normal conditions it has this problem. This is what leads me to believe it is something giving a poor signal to the EEC unit or the unit itself (though I know that is unlikely). Others have suggested a fuel/lean issue but wouldn't a low fuel supply do it all the time (pump, filter, injectors)?
Awaiting your next suggestion.
Expert:  Ron replied 1 year ago.
With the SPOUT pulled you running off of base timing which should be set at 10 degrees BTDC. Is the the cases and what is your total advance with the SPOUT installed?
Customer: replied 1 year ago.
With the SPOUT installed I get 27-28 degrees.
Expert:  Ron replied 1 year ago.
That is well with in specs. If you unplug the EGR valve does it still ping?
Customer: replied 1 year ago.
Tried it this morning. Still pings with the vacuum line removed from EGR.
Expert:  Ron replied 1 year ago.

Im not sure what is going on here , your base timing as well as advance look to be in specs. In most cases if you have a lean engine type ping it is due to the EGR valve but unplugging it eliminates that . What happens if you back you base timing down to 8 degrees BTDC?

Customer: replied 1 year ago.
I actually had it backed down to 5 before I started conversing with you and it didn't change anything. Now you know why I'm puzzled too.
Not sure if I mentioned it earlier but I have tried multiple tanks of fuel from different locations in both tanks and none of it changed anything.
Expert:  Ron replied 1 year ago.

Running the timing at 5 degrees should have solved any ping being so retarded, are you absolutely sure this noise is actually detonation?

Customer: replied 1 year ago.
Sounds like it. Not mechanical or an exhaust leak. Remember, it doesn't do it with the SPOUT out. If it were something else I would expect it to make the noise all the time. I was climbing a pretty big hill on the way to work this AM and it got worse the more load I put on it. By the time I reached the top I had to feather the throttle lightly to keep it from happening.
Expert:  Ron replied 1 year ago.

Well if its gone with the SPOUT out and with everything you have already tried I would suspect it has to be a bad PCM, the computer controls the timing once the SPOUT is in place. Unfortunately the only way to know would be to replaced it and that could be a very costly guess.

Customer: replied 1 year ago.
Not easy to find but I'm leaning in that direction too. Could be worse things to have a spare of. I will see what I can locate and update you.
Expert:  Ron replied 1 year ago.

Okay , Im leaning that was as well. Not much left at this point. Let me know.