Please help !! Stuck at work

rickyboy · #1 (**permalink**) 09-11-2008, 01:18 PM

03 F250 with 5.4 motor.
Started truck up today for work, no problems. Picked up maybe 5 gal gas on the way to work. About 5 miles alaong, notice truck started to vibrate. Sure enough, engine misfiring... Made it in to work, 30 miles total. travel. Stopped at auto parts, poured in one can seafoam cleaner, and bought 10 gallons premium fuel, thinking maybe earlier purchase of gas was bad. Drove around, no better. At lunch, barely started, went to local autozone, and plugged in code reader.
Following codes come up.
P0308(cylinder 8 misfire).
P0316(misfire detected 1st thousand Revolutions)
P0720(output speed sensor circuit malfunction)

Still here back at work, wondering what my first move should be. I will attempt to get home, but when there, what would be process of elimination for those who wold encounter same issue. Trying to minimize down time.
As luck would have it, I own a P.O.S. S10 pickup I usually use to put work mileage on, and it died on me yesterday on the way to work... Unbelievable!!
Thanks in advance for your input..
Rich

Krewat · #2 (**permalink**) 09-11-2008, 04:21 PM

Very weird that you have two totally unrelated codes come up - cylinder misfire AND an output speed sensor circuit (which is from the tranny).

Is it raining out today?

rickyboy · #3 (**permalink**) 09-11-2008, 05:17 PM

You r right. Neglected to remember my speedo has not been working for some time. Already replaced pickup sensor once in rear end, and still did not fix that problem. That is a problem for another day I am afraid.
Anyways, stopped at ford on way home, and picked up one coil and set of plugs. In garage now, and just removed the suspect coil. Want to change plug as well, but after reading all the nightmares concerning that, not sure I feel like pulling head to install helicoil if it strips. Dunno, maybe just wimping out, but absolutely need truck tomorrow morning.
FYI, I reset codes, and drove home from work, thinking if bad fuel, perhaps another random cylinder would misfire, and show up on scanner. Light came back on, and again number 8 cylinder, so that is what I am using to rule out bad fuel for now.
Stay tuned..

rickyboy · #4 (**permalink**) 09-11-2008, 10:57 PM

Success!!
Changed out #8 POC, and went ahead and changed all plugs as well.
Plug on #8 showed some good buildup from fouling. Overall,they were definitely due. About 100K on truck and first plug change now.
Took it for a good run, and feels great, with some additional pep.
As for plug changeout, considering all horror stories I have read, I was wondering what to expect. I've been turning wrenches many years, back in the day it was cars, but last 20 has been on aircraft, not F250's. I've had this truck since new, and this is first time truck demanded my attention.
As for difficulty of job, no where near as bad as some report. Yeah, its not like it used to be for sure, but for this job, seems patience and a good collection of extensions and universals do the trick just fine.
Knowing now what angles and which direction of approach works best, I would think next time would be much faster.Of course, if thats another 100k or so, I am sure I will forget all about how I did it the first time. LOL
Now if I can figure out what the hell is keeping my speedo from working, I'll be all set.
Peace!

LxMan1 · #5 (**permalink**) 09-13-2008, 02:26 PM

The speed sensor is located in the tailshaft of the trans(2wd) or the transfer case(4x4). The sensor in the rearend is for the ABS.

rickyboy · #6 (**permalink**) 09-16-2008, 12:14 PM

No kidding?
Thanks for the correction... Will go get the right one today and give it a try.
Much appreciated.

Krewat · #7 (**permalink**) 09-16-2008, 01:19 PM

On the Superduty, the VSS on the rear end IS the speed sensor.

However, your code is for an output speed sensor (OSS) which is on the tranny.

But, the code is for a malfunction, sounds like a bad connection more than a bad sensor.

rickyboy · #8 (**permalink**) 09-16-2008, 01:24 PM

Quote:

Originally Posted by LxMan1

The speed sensor is located in the tailshaft of the trans(2wd) or the transfer case(4x4). The sensor in the rearend is for the ABS.

Ok, now I need clarification
According to some threads, the VSS is located in the rear end.
Also, read somewhere here that if you buy a replacement from NAPA for this one(located in rear end) they call it the ABS sensor. Is this point of confusion? Are there two seperate sensors, one being in transfer case, and the other being in the rear end, performing together for same function? Does the one in rear axle aid in ABS function only? (That is the one I already has changed) I see two plugs on transfer case from my vantage point. One had, I believe 5 or 6 pin connector on driver side of transfer case, the other had 2 pin connector which is located just about 6 oclock position towards rear of transfer case, and plugged into a externally mounted device which is cylinder shaped. I pulled both plugs and cleaned connections, but still no luck. Which plug is connecting to sensor I need to look at?
Sorry for questions, but now I am again motivated to correct this issue once and for all. I appreciate your knowledge and sharing here.
Rich

Krewat · #9 (**permalink**) 09-16-2008, 01:36 PM

The VSS is on the top of the rear end, on the Superduty.

It's both the ABS sensor, AND the speed sensor, as the ABS module drives the speedo, PCM, cruise control, and overhead console (if you have one).

Just posted this in another thread, turns out this pic is getting some mileage:

For 2001, but should be the same, functionally:

Krewat · #10 (**permalink**) 09-16-2008, 01:37 PM

The connectors on the transfer case, one is the servo motor for shifting, the other is a switch that tells the GEM (generic electronics module) what gear the transfer case is in.

Has nothing to do with speed/abs.

rickyboy · #11 (**permalink**) 09-16-2008, 01:50 PM

Quote:

Originally Posted by krewat

On the Superduty, the VSS on the rear end IS the speed sensor.

However, your code is for an output speed sensor (OSS) which is on the tranny.

But, the code is for a malfunction, sounds like a bad connection more than a bad sensor.

Much appreciate the replies.
So then, which is the OSS sensor on the tranny. From last post, sounds like neither of the plugs I described are it. Or, does this not apply to superduty?
And just to clarify, the OSS and VSS are two seperate devices, or one in the same, and is the one in the rear end?
( FYI

Krewat · #12 (**permalink**) 09-16-2008, 02:34 PM

OK, you have an '03 F250, which is a Superduty.

The VSS is the speed sensor, AND ABS sensor, on top of the rear differential.

The OSS is the output speed sensor for the transmission and according to the EVTM, it's on the output shaft of the transfer case on a 4x4. That's from the 2001 EVTM, there's always a chance it's not there anymore for a 2003 but I doubt it.

fiftysixfordf250 · #13 (**permalink**) 09-16-2008, 03:02 PM

The oss sensor on the Superduty trans is located on the top of the trans near the rear of the case. Often times a bad COP (coil on plug) that is misfiring will cause a code for the oss. It is caused because the oss is a magnetic pickup and it picks up the disturbance caused from the bad coil. If you clear the codes the oss code should not come back. As for the speedo, check the connector at the sensor, make sure there is not a damaged tone ring, check all fuses, etc. I work for a ford dealership and have seen the misfire code/ oss and/or tss code combo many times.