I have a 2002 5.4L in an E150 van. The engine is missing consistently at 1800 rpms. I am using Autotap to monitor the misfires counter and the counter is recording hundreds of misfires in a 12 mile trip. So, obviously, the computer knows that misfires are occurring. But, no "possible failures" and no "failures" are being reported. I know the Check Engine light bulb works because I can see it when the key is first turned on and all of the dash lights are illuminated. But, nothing is being reported in the error tables in the computer. What is the criteria for a misfire failure to be reported as an illuminated Check Engine light?

I am hoping every day that the light will turn on so that I can retrieve the error which will show me the number of the COP that is failing.


Thanks.

 

Read the individual cylinder misfire PIDs to see if the misfires are unique to a particular cylinder or cylinders assuming your PCM is running an OBDII calibration (Check the label under the hood).

Additional Ford OBDII information is available at http://www.motorcraftservice.com/vdi...&menuIndex1=15

 

Individual Misfire PIDs? Is that available via OBDII? I am using Autotap to read the OBD data. It was showing the misfire counter incrementing steadily but no errors were being recorded. Finally today, after 2 weeks of misfiring, misfiring on cylinder 3 was reported. It is reported as a probable error and a confirmed error but the MIL is not lit yet. I guess it needs to fail 3 times in a row for the MIL to light? Anyway, it looks like I have another COP to replace. They are going slowly on this engine.

Thanks.

 

Check under mode $06 data if supported.

 

Stock COP's?

 

Yup. The van is 10 years old and it has about 135K on it. The original COPs are failing one-by-one. If they weren't so danged expensive, I would buy the whole set at once.

 

I wouldn't think at that age/mileage they'd be failing---my own '00 E250 has 260K+ miles and the OEM COP's are running just fine. In fact a year or so I installed Granatelli's stock replacement COP's and they're the ones failing now, one-by-one. When outside temps drop below 35* overnight I'll get MIL indication of misfires. Running the engine a short while to warm it, restart and the rough idle is gone. I'm back to replacing the Granatelli's one-by-one back to the stock recently removed COP's without a single hiccup.

So while the OEM's are pricey their street price has dropped considerably, especially through on-line retailers like RockAuto.com. Yeah its a chunk of money to do them all at once but if it comes to that at least you'll have restored reliability and eliminated that aggravating problem.

Not sure if you're due for new Motorcraft plugs and boots but I'd also check the wiring harness connectors to the COP's---discovered one of mine was failing to lock in which caused a consistent misfire. NAPA has replacements for these---about $20 each but worth it IMHO.

Hope this helps even a little!

 

Thanks for the info. I didn't realize that Rockauto sold the Motocraft parts. I will look them up. I also didn't know that those connectors were available from NAPA. That tidbit could be worth "its weight in gold". Thanks.

 

Another thought on the NAPA connectors---passed to me by my Merlin The Mechanic good freind:

Instead of cutting loose and splicing in a new consider removing the contact terminals inside the old connector first. Next remove the contact terminals and wires from the new connector. Now insert the contact terminals into the new connector body. This retains the factory appearance which tends to be neat and tidy.

This works and does require almost a surgeons touch and tiny probes etc but the end result is worth it IMHO. It's done quite frequently in many shops I'm told. Of course if time is more important then chop, strip, crimp and drive away!

Just an idea tossed out for consideration.............because I wish I'd known of this before chopping, stripping and crimping!