02 engine miss

[30fords]

I have an 02 with an engine miss. it's worse when running a constant speed or under a load. when you pour on the gas though it pretty much goes away. Coil? intake? any gueses? oh and anyone living in the north with a 02 or older should check their shift cable where it attaches to the trans. mine just rotted off.

[Blue)(Fusion]

It's likely a COP (Coil-On-Plug). You can verify in a couple of minutes.

With the engine running, pull the connector from one fuel injector at a time. If the engine RPM changes, that cylinder is firing normally. When you pull a fuel injector connector and the RPM does not change, than you found your culprit.

Once you know which cylinder is missing, swap that COP with the cylinder next to it. If the miss moves to the cylinder you moved the suspect COP to, the COP is bad and needs to be replaced. If it did not move with the suspected COP, then it is the fuel injector, spark plug, or less likely the compression on the cylinder.

[30fords]

Originally Posted by Blue)(Fusion

It's likely a COP (Coil-On-Plug). You can verify in a couple of minutes.

With the engine running, pull the connector from one fuel injector at a time. If the engine RPM changes, that cylinder is firing normally. When you pull a fuel injector connector and the RPM does not change, than you found your culprit.

Once you know which cylinder is missing, swap that COP with the cylinder next to it. If the miss moves to the cylinder you moved the suspect COP to, the COP is bad and needs to be replaced. If it did not move with the suspected COP, then it is the fuel injector, spark plug, or less likely the compression on the cylinder.

thank you.
I did try unplugging one cop at a time and everyone changed how it ran. i will try pulling the fuel injector connectors one at a time. i doubt it's the pligs i replaced them all a couple months ago. i did replace the dpfe sensor a few days before it started. also i drove it 750 miles in about 15 hours and it ran fine. it didn't start untill the return trip.

[Blue)(Fusion]

Check the DPFE sensor again. Make sure the hoses are firmly attached to the DPFE sensor and the EGR tube and that the electrical connector is attached firmly.

Except usually DPFE/EGR problems only show up under light load at constant cruising speeds (when commanded open).

[30fords]

Originally Posted by Blue)(Fusion

Check the DPFE sensor again. Make sure the hoses are firmly attached to the DPFE sensor and the EGR tube and that the electrical connector is attached firmly.

Except usually DPFE/EGR problems only show up under light load at constant cruising speeds (when commanded open).

thank you, I will check that. it happens at cruising speeds up a grade. if you step on the gas it goes away. it also does not do it at idle.

[guitar56]

i have 1999 mercury 4.6 miss fire on #2 and#7 cly changed coils changed injectors and plugs stayed the same if i poll coil put plug in it the plug fires good put back in wont fire could u give me some help on what to do next all ready checked compresion

[Blue)(Fusion]

Why didn't you pull the spark plugs on those cylinders? If the injectors or COPs are not the issue, than it is a 98% guarantee it is the spark plugs fouled or has too much/too little gap. The other 2% is a compression issue, which you'd probably notice in other ways.

[jthomp23777]

Have a 2000 Grand Marquis that has a rantom engine miss between 40-50 mph. I suspect a coil. I tried Blue Fusion advice of unplugging each fuel enjector, but it only made the engine run slightly rough meaning it's was only running on seven cylinders. Currently the plugs were changed by another person a few months ago, but the plugs are not the Motorcraft SP493 Platnium, wonder if that can be a problem. EGR valve and surrounding vacuum lines appear fine. Any other ideas. Vehicle has only 65000 on it.

[jthomp23777]

Re: 02 engine miss

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Have a 2000 Grand Marquis that has a rantom engine miss between 40-50 mph. I suspect a coil. I tried Blue Fusion advice of unplugging each fuel enjector, but it only made the engine run slightly rough meaning it's was only running on seven cylinders. Currently the plugs were changed by another person a few months ago, but the plugs are not the Motorcraft SP493 Platnium, wonder if that can be a problem. EGR valve and surrounding vacuum lines appear fine. Any other ideas. Vehicle has only 65000 on it.