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Discussion Starter · #1 ·
I just had spark plugs, ignition coil and oxygen sensor replaced 3 weeks ago. While out of town, I had a "service engine soon" light come on and it was misfiring badly. It happened out of the blue and I had to fix it or have it towed which would have been very expensive. A week ago I did put premium gas in it and it went away. I just filled up with regular again and it's pinging again. Before I had the coil, plugs and oxygen sensor replaced I could put regular gas in it without pinging? Any thoughts on why it is pinging now? Will I have to use premium gas from now on?
 

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What kind of spark plugs were used? Ford's ignition systems can be fussy over what type of spark plugs are used.
 

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+1..
I would seriously consider running the Motorcraft OE spec plug, no more, no less.
It sounds like regular copper plugs were used instead of double platnum's. (or iridium tip with platnum electrode)
 

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Is your 99 Vulcan a flex fuel engine????

You can go to the Motorcraft web site, enter your vehicles Vin # to look up the specified spark plug, ect for it.
 

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You need to be running APP103 or APP104, AP104 is a single platinum and should not be used on a waste spark system. That being said, the spark plug is unlikely to be the cause of you pinging. Pinging is caused by either something overheating inside the combustion chamber, or by a lean condition. The lean condition is more likely. So what cause a lean condition?

The three big culprits are vacuum leaks, which probably wouldn't be noticed under acceleration, and low fuel pressure, which would only be noticed under acceleration. There are other things that could be going on two, but those two issues are going to be the most likely. I would also clean the MAF sensor, because it it gets dirty, it will report less air going into the engine, and that will result in a lean mixture as well, especially under acceleration. This is particularly likely if you have been using a cheap air filter or an oil coated performance air filter.

I would check all the vacuum lines, especially the PCV elbow to see if they might have cracked. If that checks out, there could still be leaks in the upper or lower intake plenum. That can be harder to detect without the use of a smoke machine. Some advocate the use of starter fluid or some other flammable liquid sprayed around the suspected leak, which can work, the problem with this method is that fairly often the computer will correct for the change as you are spraying the leak, so you may not notice a change in the engine RPM. If you have access to a scan tool, you can have an assistant watch the short term fuel trim while you do this, and the STFT% will drop sharply when you spray the leak. A smoke machine can be found at many repair shops, and will find most leaks effectively and quickly, and a test is not very expensive.

The MAF sensor will affect more conditions, but especially under heavy throttle because the computer ignores the O2 sensor when you accelerate. It relies on what the MAF tells it, and if the MAF is reporting less air that the actual flow, you will get a lean condition when you accelerate. Normally there should be a MAF code associated with this, but I have had problems with the MAF that did not have any codes, yet you could feel performance issues.

Fuel deliver can be tested with a fuel pressure gauge while replicating the conditions. A plugged filter or a weak pump will cause the pressure to drop when you accelerate. This will cause the mixture to lean out and that will cause pinging.
 

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^^^^ +1

Waste spark ingition systems require double Platinim plugs. Single Pt plugs are for distributor systems or COP systems.
 

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Discussion Starter · #8 ·
thanks for your replies. my owner's manual says to replace with
AWSF32PP. Is the autolite ap104 the wrong replacement plug for my car?​
 

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The P in AP104 means single Platinum (only center electrode has a Platinum tip). The PP in APP104 means double Platinum (Both the center electrode and ground electrode have Platinum tips / inlays). You have the wrong plugs. Not saying that the APP104 will fix your problem, but I would put in the correct plugs and see if the problem still exists.
 

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K-H,
Though I don't have the same problem, I stiil appreciate your long answer.

By the way, what is waste spark system? On my cars, I installed either APP or AP, depending in availability at WalMart.
 

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Waste spark

K-H,
Though I don't have the same problem, I stiil appreciate your long answer.

By the way, what is waste spark system? On my cars, I installed either APP or AP, depending in availability at WalMart.
This system fires the plug every time the piston comes up, not just on the compression stroke.

Fires from both ends of the coil, so one plug is positive polarity, one negative. Thus the need for double platinum.

coil pack with 3 coils is this way. Individual coils on each plug is not a waste spark system, as is a distributer system.

-chart-
 

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Discussion Starter · #13 ·
Hi All and Thanks for your replies! Why does my car not ping with premium and ping with regular? Again, they put in AP104 plugs,new coil pack and oxygen sensor. BTW, I have the "U" engine.
 

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Because higher octane resists detonation, thats what octane is for. What octane is your "regular" grade? The recommended octane fora Vulcan is 87, I wouldn't go lower than that.

Check your fuel trim. If You fuel trim is high, even if it doesn't set a code, that points to a lean condition. It takes a bad lean condition before it sets a code.
 

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Discussion Starter · #15 ·
What is a fuel trim and how does one go about checking it? BTW, my car didn't ping until I got new plugs,coil and oxygen sensor after my car started misfiring on an out of town trip.
 

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Fuel trims are the corrections the PCM applies to the factory programmed fuel values. Positive fuel trims indicates the PCM is adding more fuel than the preprogrammed values, negative = less fuel added. You need a scan tool that will show the short and long term fuel trim PIDs (parameter identifiers) in either numerical or graphical formats.
 

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Discussion Starter · #17 ·
Thanks. I will start with having double platinum plugs installed (APP104 instead of AP104) and go from there. I'm hoping that this will cure the pinging. If not I will check the other things that you all have brought up. Again,thanks, you all are very helpful!
 

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I don't think it's the type of plugs that are your problem, even though they're suppose to be double plats.

Khan is right, the pinging is detonation. That's why the higher fuel grade eliminates it. Higher grade fuel resists detonation because it's resistant to pre/auto-ignition.

Detonation or pinging is generally caused by...

- Low fuel grades
- Too high compression or manifold pressure (turbo/super charged) for the fuel grade (unless your engine is modified you don't have this problem)
- To high cylinder temperature caused by too lean of a mixture
- Something in the cylinder remaining hot enough to pre-ignite fuel/air mixture

The fact that the plugs got changed recently, I would pull them and check to make sure they're clean. One thing that can can cause ignition problems is anti-seize. If there was too much anti-seize applied it can creep down the threads and onto the spark plug. The metals in hi temp anti-seize can short a plug or remain hot in a cylinder to cause pre-ignition with a low grade fuel.

If that doesn't work you can install water-meth system for ADI (Anti-Detonation Injection). That will keep it from pinging. ;)
 

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Discussion Starter · #20 ·
OK, I'm confused. I went to the Ford Dealer and they said the AWSF32PP is discontinued. They are substituting the AGSF32FM which is the same as the Autolite AP104. The AP104 is a single platinum plug!? Why would Ford be recommending now a single platinum plug in their DIS or waste spark ignition?
 
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