2004 Ford Taurus - 3.0L DOHC Multiple Coil Codes Fixed!

[jbadenoch]

Hey, first time poster here. have a 2004 taurus in my shop. Vehicle came in running rough.

Tune up parts were worn out so we tuned it up, factory plugs and boots, has c.o.p ignition system. Mil was on also with po351, po352, po354 coil codes. After tune it still has a skip. Did a power balance test and the only cylinder not working is #4. Also still has repeating codes, po351, po352, po354. Checked spark at all the coils and they all have great spark. Just for the heck of it I swapped coil #4 for coil #3. The skip in #4 is still there, and same codes. Swapped #4 injector with #3, skip still #4. put new coil on #4 even thogh it had good spark, skip still #4, still same codes.

Wiggled and jiggled and pulled every wire and wire harness,and did continuity tests on every related wire and connection. Did a compression test, all cylinders right at 200 psi. smoke tested eng for vac leaks, has no leaks. Watched the injectors spray fuel, all good. Fuel pressure is good 48 p.s.i. Customer also stated that ac not working. Diagnosed that as a bad pcm, was not triggering ac relay. Sent the pcm off to be rmfg. The hope was that the skip may also be pcm related. Pcm came back a few days later but neither issue was resolved.

Spent several hours after that re-checking everything ac related and determined pcm not fixed correctly and are sending it back for further repair. I am not hopeful at this point about the pcm fixing the skip. If anyone has any thoughts or ideas about the skip, please help.

Thanks Bob in Greenville SC

[BONITAVALLEY76]

This one sounds fun brother. I searched these symptoms in Identifix (Napafix if you're a Napa Autocare Center its a better deal), and it mimics what you've already been down. It had this to say about the codes setting specifically: "The coil primary codes will set if the PCM has identified the loss of ability to control the COP primary circuit. For this to occur on a single occasion would result in a stall and no start condition. Since the vehicle misfires and runs poorly but doesn't stall completely when the condition occurs, the PCM is highly suspect for failure." Identifix suggests checking for an alternator problem that could cause electrical noise that could confuse the PCM. We have to assume you're not getting bum PCM's. If you have flashing capability I recommend you check that they're not just putting an old calibration on it. Heres the rundown of the common solutions to the problem:
6 - Coil On Plug(s) (COP)
2 - Powertrain Control Module (PCM)
1 - #5 Ignition Coil
1 - Coil On Plug (COP) Wiring
1 - Harness
1 - Intake Plenum O-Rings

Good luck brother!

[ricmorin]

Those are control codes. Primary side of the coils are suspect. Probable PCM issue. I'd familiarize myself with the use of a scope and current ramping as this will easily tell you where the problem lies. Also, I gave up on reman units long ago. Get a good pcm from the dealer, install it and program it. Done deal. The 301, 302, 303 codes are on the secondary side. Anything from a bad plug to low compression can cause those.

[BONITAVALLEY76]

Boss just poked his head in the door and said that you can check for blown intake plenum seals if they are blown across by removing a plug and then inducing smoke or air into the cylinder adjacent he said it drove him nuts.

[steven kiser]

have a fleet of these and have run into a few issues with these. first is tsb 04-14-10, a harness issue that can cause multiple failure issues. the second is and i'm not sure exactly which one applies to this one. one some i've run into intake issues where the egr runner is compromised and intake needs to be removed and cleaned. the other, there is an updated intake available for it. on the replacement intake the bolts are shorter that the original so be aware. one the first one we did the new bolts were missing and we had to cut about an inch off the original. the replacement intake usually has to do with 02 codes but i wouldn't pass it up just because of that.

the plugged egr ports threw me a curve ball the first time because i just couldn't believe it would cause the multiple failure issues. it sounds like there have been issues for a while and the customer just can't drive it this way anymore. i've had head bangers before and after grilling the customer have found out that it all didn't happen at once. each fault appeared at different times and finally the power loss was so great it couldn't make it up the hill at the end of their street. multiple faults may and usually do have multiple fixes.

[jbadenoch]

yeehaw! pcm fixed both issues. Just wanted to let you know what it was.

[steven kiser]

thanks for posting the fix.