Severe misfiring on 5.4L

[gflat65]

2002 expedition 5.4L
There is a severe misfire and hesitation at all speeds. I can't get my scanner to allow communications (scanner works on all of my other cars).

I changed the fuel filter and did a sea foam treatment today. On the blow out drive, the battery light was on, went off, but then came back on during the drive

I had the battery checked. It's low (12.3V), but still had over 750 CCA. Could a weak alternator create issues with the scanner? What else can I check to determine why I can't communicate (I used to be able to on this vehicle). I notice that there appeared to be a leak at the negative post on the battery after the blow out drive.

No idiot lights staying lit, but Service Engine Soon will flash sometimes when its misfiring really badly (can't go a mile without a misfire, but the degree of misfire changes).

Plugs have ~8k miles in them (motorcraft). I've changed a few cop's over the last year, but didn't do them when I replaced plugs. Truck doesn't get driven much, obviously.

Replaced several sections of vacuum tubing today (lots of rot).

Any ideas on the OBDII communication problem?

Ideas on what else to check on the misfire/hesitation/power loss issue?

TIA

 

[gflat65]

Got the battery fully charged, and was able to connect to the ECU, but no codes were stored.

It had a miss at idle (normally doesn't), so I pulled injector or cop plugs, and it seemed to change on #3, so I changed out the cop and went for a drive. It seemed to be doing well for a minute, then started the heavy misfire. Seemed a little better than before the cop change, but still heavy.

The battery light came on shortly after the start of the drive, then was no longer able to connect, so I guess that answers that.

Put the battery back on the battery tender, and it appears as the battery is below the 85% charge value (per LEDs). It reads 12.57Vdc.

Could a bad charging system cause misfires?

Pulling the alt tomorrow to replace.

 

[swagfu]

I would think that a bad charging system could definitely cause issues for you and not just misfires. Anytime you have a pulse in the electrical system you can have a variety of problems. Are you able to test the alternator as well as the battery? I had a similar issue on a motorcycle a few years back and I charged the battery up and it got me home, but when I turned it off the bike wouldn't start again. Ended up being the voltage regulator had burned up from being on a battery tender too much. So I replaced the battery and regulator and haven't had a problem since. Check them both.......

 

[1955moose]

These vehicles are very dependent on a proper battery, and charging system. We've had members that had corrosion on alternator terminals that caused all kind's of problems. Check and clean all your connections involving charging system. Your battery may be passing a load test but could still be shorted, seen it! Report back your findings.

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[gflat65]

Thanks guys. I'm going to test the alt today and see what that tells me.

When it comes to COP's, is Motorcraft still the only real option, or has someone stepped up with another comparable option? I looked for Visteon's but couldn't find any at alanisdeals. I think changing the COP's would just be a good maint course of action. Except for the few I've changed, they could be the originals.

 

[1955moose]

The Ford oe ones usually work best. Some of the members have had good luck with accels brand. Why not use a volt/ohm meter and test your old ones first. Theirs specs online, real easy to do. Coils unless wet usually last the life of vehicle. You do want to change the coil boots though, their available separate.

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[1997SCEBFEX]

I think inferred here, check your cables too.
++ on ohming out COPs.

 

[1955moose]

Only 97 and early 98's used cables, after that it was electrical boots and individual coils. He can test the primary side, along with the secondary side with the boot.

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[gflat65]

Changed out the alternator. The battery is charging now, but, against hope, it didn't affect the misfire.

It accelerates, but seems to hit on power just every so often (like it's surging?). Worse as it gets warmer. I've got an exhaust leak on the right side that I've been using to hear the miss better (plan to replace the stock manifolds with headers in a few weeks).

The exhaust tick used to hit consistently (if, for example, each 'tick ' was one per cycle, it used to hit every cycle). Now it hits very inconsistently. After it warms up, maybe one tick per 3-6 or 7 cycles (hoping that gives an idea of the change).

After running it on the street for 20 minutes or so (FOT as many times as I could to try to find a pattern in the 'tick'), i pulled into the driveway and heard a fairly constant cyclical buzz (kind of like sound of higher frequencies on sheet metal - zzzt zzzt zzzt in a fast pattern). I crawled underneath, and it sounds like it's coming from somewhere near the cat or the transmission? Fairly sure it was coming from inside something (wasn't as loud it close as an exterior shield buzzing).

Still no idiot lights.

I'll check the current COP's with my fluke.

 

[Plati]

My understanding is ... drive too much with misfire, expect to ruin your Cats. Expensive to replace them.