Mechanics

DIAGNOSTIC CODES: PO305 AND PO316

1930 Ford Taurus

I have a 2002 Ford Taurus, 3.0, 24 Valve, DOHC, automatic transmission with 102,000 miles. Over the past couple of months the check engine light comes on and the codes are always the same - PO305 & PO316.

I have changed the spark plug, plug wire and just replaced the ignition coil. The check engine light came back on. What else could it be?
Avatar
Mike McFarlin
July 7, 2007.




There is a technical service bullietin about this, the PCM need to be reprogrammed with the latest software.

#04-25-14

The PO305 is the # 5 cylinder that is misfiring, and causing a rough idle.(Or contributing to it) I would start with a re-programming, as there is a tsb that fits the description. It isn't a gaurentee. Welcome to our world : ) : shock: I " think" the will be the solution.
AD

Mike,
I apologize, I deleted your e-mail and just found you.

Was a compression test actually done on the cylinder?

Okay found your e-mail.

I did some research on the codes. They may or may not be tied in together. The po191 is low fuel pressure. This may be causing the po305 misfire. The problem seems to be the potential time for the failure to show itself. IT may take more than 3 hours of idling before it acts up. This may be a bad fuel pump wanting more voltage to maintain fuel pressure or it may also be a bad fuel rail pressure sensor. It may be cheaper to try a rail pressure sensor than to spend a ton of money on diagnosis. HArd to say. I have heard of valve springs breaking and that may be the po305.

On the po316, I have found cases of the coil being bad and causing the rough idle, and a bad connection on the B+ wire at the coil.

The p1131 may be the bank one sensor one Oxygen sensor.

So there is room for several problems or one that is affecting the others to happen. Need to do some looking or some testing or replacing or troubleshooting.

Paul,

I told you I would update you on the results of the repair to correct PO305 and PO316 diagnostic codes on my 2002 Ford Taurus SES.

Well, it took almost a month and $2,019.86 to repair. The problem was 2 burned exhaust valves, one in cylinder 5 and one in cylinder 6.

Breakdown: $1,194.00 Labor
$ 603.12 Parts
$ 133.00 Sublet
$ 36.94 Misc Chg
$ 52.80 Tax

Interestingly, They had (?) To replace the radiator overflow bottle. (Broke by the tech, I'm sure) Was no problem before the repair. Replaced oil pan gasket and front main seal. Probably another, OH MY!

In their favor, They loaned me a 2007 Focus for 10 days to take on vacation.

Thanks for all your help!

Tiny
Mike McFarlin
Sep 18, 2007.
Thanks for the update. I wonder if the burnt valves were from vavle spring failure. Although it's a good chunk of change, and some things were obviously questionable as you relayed; It is still cheaper than car payments. It usually runs about 7-14 cents per mile for maintenance and repairs.


AD