00Codes P0354,355,356 Coils not firing

[gbic1]

00 Taurus not firing on three front coils. number 4 5 6. Checked the wiring. Changed PCM per Ford Dianostics. Swaped coils. Changed cam sensor. It is getting 12 volts to coil but is not ground siding them.

[brokenantimatter]

fault wiring harness?

[gbic1]

Checked wires for proper resistance per Ford shop manual. All ok

[shorod]

I think the wiring harness that brokenantimatter is referring to is the harness for the PCM.

How did you verify that the coils are not being grounded? If you were using a DMM, I'm not sure it would have a fast enough response time to determine if the PCM is grounding the coil or not. You really need to use an oscilloscope.

Does your Taurus have a separate coil for each cylinder, or 1 coil for a pair of cylinders? I guess if you are getting codes P0354, P0355, and P0356 you have one coil per plug.

If it is one coil per pair, then the coils must be working fine and the PCM must be providing the proper signal to the coil for the paired cylinder (ie: the wiring harness to the coil must be okay).

-Rod

[gbic1]

I did the test procedure according to the factory Ford repair manuals I have on cd. I also substuted a good coil. This car is a COP (coil on plug). My cd stoped work to day . I wanted to go throught eh steps again and make sure I did not miss any thing. I did the pinpoints for JF starting with one. It has you test for 12 volts at the coils and for flashing light during crank just like testing a bad injector. I tested the ground circuits back to PCM for resistance and they are fine. This car was diagnosed by some one else. It came in to his shop with the intake blown open and he said a rod knock. I installed a used engine complete with all wiring and coils. The rear converter was pluged and was causing the back fire which blew the manifold. We replace the manifold and notice it now has no power. That is when I checked the codes and the coils for spark. I still had the other engine here so I swaped the cam sensor and some coils. The crank sensors both ohm to the same reading. It will not start withh hte crank sensor unpluged. I did not check the crank sensor on a lab scope but I can. Looking at the wiring diaghram it grounds throughthe PCM. We could not get a new one yesterday so I bought a used one and had the dealer reprogram the PATS system. Still runs the same. ?????????

[shorod]

Originally Posted by gbic1

....We replace the manifold and notice it now has no power. That is when I checked the codes and the coils for spark. I still had the other engine here so I swaped the cam sensor and some coils....We could not get a new one yesterday so I bought a used one and had the dealer reprogram the PATS system. Still runs the same. ?????????

You mention the engine had no power and that is why you checked the codes. Did the engine seem to be running smooth? If you had three misfiring coils, I would expect you to be able to notice it in the way the engine runs. Also, three misfiring coils could definitely cause a converter to get plugged, maybe the used engine has the same issue as the first engine. Or were you not having this problem on the old engine?

It looks like the two banks of coils get power from a common splice. Maybe you have a corroded connector or splice to the suspect bank of cylinders and you have enough current getting through to light a test light, but not enough to fire a coil properly? Are you using an LED test light or a filament bulb test light? LEDs take very little current to light.

I would suggest backprobing the coil connectors and watching the primary signals on a lab scope. Then connect the positive lead of the scope probe to battery voltage and leave the ground connected to the appropriate terminal on the coil. If the pulse looks different, start checking the wiring and connections on the hot side for corrosion or loose connections. If the pulse looks the same, then backprobe the coil triggers as close to the PCM as possible. If you now have a nice trigger signal, then I'd suspect the wiring between the coils and the PCM.

Keep in mind that since the coil may not be firing, the signal displayed on the scope may look significantly different (probably higher amplitude spike) than a known good trace would.

Good luck!

-Rod

[gbic1]

Found the problem. Engine was delivered complete with wiring harness and was correct for make model and year. When the salvage yard pulled the 104 pin connector out of the PCM they dislodged the pin for cylinders 4 5 6. All three of the wire are the end three wires on the short end of the harness. I dont have a 104 pin break out box so I just use special thin wall test probes and they were long enough to reach the wire when the PCM pins werent. Pushed wires back into connector and car runs fine. Thanks for the support.

[shorod]

Excellent, glad to hear there is another Taurus back on the road (or soon to be).

-Rod

[brokenantimatter]

Glad to see you engine is up and running and that I was right on the wiring harness X-D
Two questions:
Coil on Pack for a 00 model would mean you have the Duratec right? How in the hell would get a "rod knock"?