Contour Enthusiasts Group Archives Forums Modifications 3.0L Duratec Finally....

After 8 long months and 2 bad engines I have a running 3L (170psi). It's a 98 block and heads with SVT cams as well as an aftermarket flywheel, 4 new O2 sensors, FMS wires, Pro-M 75mm calibrated for 24's. The engine seems to be running ok with one exception that I can't figure out for anything. The car is kicking the CEL with codes P301 through 306 (Miss-fires at all times. When accelerating it will hesitate really bad until around 3500 at which point I have no trouble all the way to redline. The car has a new Cat in it with punched out Pre-Cats. Originally I had thought that the car was running lean. After taking out the plug today (autolite copper core .48 gap) they are carbon fouled.. black as can be... indicating a rich condition.. I can't figure out why it would be though. If anything I would have thought lean without MIL eliminators in place for the hollowed Pre-Cats. ?? Any suggestions would be great.. can't figure this one out at all. Also I must mention that this is my second set of plugs in the car after noticing the first set being fouled. I have also replaced the TPS with the 3L one as the original was bad. I have also replaced the IAC.

-Nate
98.5 SVT
-all the goodies

Nate:

A couple of things here strike me as odd... They might give some insight as to why you're misfiring...

-Wires: Wires will cause misfires very quickly- Are they brand new? Worn in any way? Did you use dielectic grease between the wires & plugs, and wires & coil?

-Copper plugs: The SVT cams and computer that you're using are computing A/F and timing based on a very hot, platinum-based spark. The only time I've seen coppers is under FI.

-Rich condition: Unburnt fuel and carbon build-up from those misfires. I would tend in this case to verify the MAF/Injector combo. Which injectors are you using? Are you positive on the MAF calibration? Extreme rich in the low band is screaming either bad induction or bad A/F calculations.

-TPS: After installing the new TPS- Are you properly calibrated? Proper voltage ratings are critical at closed and WOT. This would throw off the A/F mix really quickly.

-MIL Eliminators: Recommend these, but only to avoid the "catalyst below efficiency threshold" CEL. Those two O2s are for that function only- I have seen no evidence that their signals influence A/F mixture.

Hope something here turns on a light for ya...

DanG,
The wires are brand new. The main reason for copper plugs would be that I do run Nitrous in the car or I should say will be once it is running right. The TPS is calibrated correctly. The MAF is calibrated for 24 pound injectors and was custom done for the car. I am running 19 pound injectors as of today because the 24's that I have seem to have bad seals on them. I would think that with the 19's in there the car should still run ok as I had this same problem even with the 24's.

-Nate

Nate:

Now THAT'S weird. You shouldn't be running the 19#ers on the 24#-calibrated MAF, but that would make you run LEAN (injector pulse width shorter because of the 24#ers more ample fuel delivery).

I now can't imaging why you're running rich and/or fouling... Try the stock MAF for as long as you're running the 19#ers... See if that makes a difference.

Just tried the stock MAF with a complete reset of the computer.. still has a missfire.. getting a missfire in as many as 4 cylinders. I am going to try swapping out iginition packs with an extra that I have here as well as checking the ends of the FMS wires to make sure they have good contact..

change to stock plugs and wires! Do it now! Hurry!

Dang it Tom... I was half way to the door to change my wires back to stock. Don't yell at me like that!

yeah I'm about 20 minutes away from trying that one.

Ok.. tried the wires... no go.. still missfires and toss's the codes for it. I am going to try a different ignition pack to see if that will help the issue any.

ok.