Help! Sudden miss in 4.6 (97 T-Bird)

While driving it just started to miss a little then got worse. Service engine light started blinking. Made it home OK but it's not drivable now. You could nurse it along for a few blocks but it shudders and pops. New one for me. Bad gas? Fuel filter? Any help greatly appreciated.

Frank

Reply to
F.H.
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If I get someone to hook up a computer will it diagnose the problem?

Reply to
F.H.

read codes and preform a power balance test

hurc ast

Reply to
hurricane 575

Probably not, unless it is a true miss. Best approach is what Tom suggested to you.

Rodney

Reply to
rodney

F.H. wrote:

The "computer" will only identify the cylinder(s) that are not firing, either through a misfire code or a power balance test. Once the "bad" cylinder(s) is identified, you will have to check for compression, spark, and fuel supply to that cylinder.

If the miss started suddenly, the problem is likely a dead spark plug, a dead coil, or a dead injector. Another possibility, if the miss developed over a period of time, is a spark plug wire arcing through the spark plug boot.

You can identify the missing cylinder by unplugging the electrical connector on the injectors one by one with the engine running. You will notice an RPM drop or a worsening miss. If you find one that makes no difference, that's your dead cylinder. Pull your spark plug wires off of the spark plugs and check for oil on the boots and for signs of arcing, usually grey spots and pinholes on the side of the boots or grey pencil like lines out of the boot opening. If there is oil on the boots, the valve cover seals are leaking and will need replaced along with the wires. Remove the spark plugs and look at them. The plug in the dead cylinder may look either cleaner or dirtier than the rest. You can rule out the spark plugs by replacement, they are inexpensive and probably needed anyway. About $16 max. You can test for spark at each wire with an inexpensive Spark Tester. It looks like a spark plug with a clip on the side. No spark points to a dead coil pack. (This will usually cause a miss on 2 cylinders). If the plug wire and spark plug on the "bad" cylinder are ok, and there is spark present, you likely have a dead injector. The above steps should locate your miss. Low compression will cause a miss, but it is uncommon. If you have access to a compression tester and know how to use it, it can't hurt to check. Another possibility is a PCM not triggering a section of a coil or an injector, again this is not common.

Hope this helps, Tom

Reply to
Tom Adkins

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