Fox Ping Under Load

Jan 8, 2014
Ok I had to describe my issue as I see it. My 1989 5.0 pings under 3/4 to full throttle. I will give u the rundown to hopefully eliminate some obvious questions. New plugs/wires/ignition module/cap/rotor/fuel filter and 10 degree of timing advance with 93 octane gas(pings at 12deg and at 14 deg advance) timing chain/water pump/o2 sensors. It has a cold air intake as its only engine modification. It has 90k original miles. I have owned 10 mustangs and this is the first I have had with with this issue. I also replaced the coil. It has done this even before I replaced all the parts. I would appreciate any ideas. check engine light. I am not too familiar with pulling the codes on the older system I did it on my SHO. I am sure that will be my next step to learn how to do it. Any theories will help:)))
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No chip...stock. Here are the SHO picts. But lets stay focused:)))


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Any chance the timing mark on the crank pulley is off there for giving you a false timing reading when your setting the initial timing?
Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on.

Dumping the computer diagnostic codes on 86-95 Mustangs

Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.

Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

Post the codes you get and I will post 86-93 model 5.0 Mustang specific code definitions and fixes. I do not have a complete listing for 94-95 model 5.0 Mustangs at this time.

Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. On a manual transmission car, be sure to press the clutch to the floor.
Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.



If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.


The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.


The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and driveablity problems

Some codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off, and clutch (if present) is pressed to the floor, and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

Your 86-88 5.0 won't have a working Check Engine Light, so you'll need a test light.
See AutoZone Part Number: 25886 , $10

Alternate methods:
For those who are intimidated by all the wires & connections, see Actron® for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see Equus - Digital Ford Code Reader (3145It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $22-$36.
Overheating or excessive carbon buildup in combustion chambers can cause pinging.

Does it ever knock and "run on" when you try to turn it off?
Just ordered the Equus 3145 code reader for the future issues I am sure I will have. I am also doing the sea foam treatment and seeing what the codes tell me about a possible bad EGR. I will report after lunch about what codes I get by the method above. I have big plans for this car:)))
I did not have the time to run the codes at lunch. However....after the post by MFE92 I will defenitly tray that one. I had cleaned the MAF when I got it but then I proceeded to clean the k&N stock drop in filter and re oil it. I ran that filter for probably 2 months before I replaced it with a conical non oiled unit(cold air intake). I had already cleaned the MAF so I just installed it. I will clean it tonight and see if that helps. thanks for all the suggestions!!!