Taurus Tribulations

Car: 1997 Ford Taurus Station Wagon, 3.0 Liter Vulcan (OHV) v6 engine. Automatic transmission. 165,000 miles on odometer.

A few months ago the car started to run rough and miss. It would miss at idle as well as at highways speeds. It got so bad that car wanted to stall out while driving or while stopped and idling at traffic lights.

At that time I pulled a P0402 code, ?Exhaust Gas Recirculation Flow (EGR) Excessive Detected?. TSB for this car says a P0402 is often caused by a faulty DPFE sensor, so I went ahead and replaced DPFE sensor. This helped quite a bit, cleared the P0402 code and made car driveable again, but did not eliminate the engine misses altogether.

I went ahead and replaced the plugs, wires, and coil pack; since it was time to do all that anyway. This helped even more, but still did not completely eliminate the engine misses. But the repairs I did make reduced the problem to a minor one, so I ignored it for a while.

However, lately the engine miss problem has grown worse, though the car is still driveable. The misses are getting more frequent again, this time accompanied by what sounds and feels like is occasional muffled backfire on acceleration. If things continue to degrade I?ll probably have to stop depending on the car to get to work.

The entire time (18 months) I have owned this car it has also given me P0420 and P0430 codes. I replaced the catalytic converters and the O2 sensors. This did not clear the P0420 and P0430 codes (my guess is the aftermarket converter I put in there is not up to snuff). I gave up on that because our locality does not require emissions inspections and there were no driveability or engine performance problems associated with the P0420/30 codes. I do not believe the catalyst issues are causing the present engine misses. I have run this by some mechanics and they also doubt the catalyst problems are causing the engine misses. Though I have been wrong before, I think it is worth noting that I also own a second Taurus Station wagon, that one a 1996 that is virtually identical to this 97 that I am writing about. It also has the P0420 and P0430 codes, but the engine runs and purrs like a kitten.

I did put in a new fuel pump when I first got this 1997 Taurus 18 months ago. I had the fuel pressure checked recently to rule out recurring fuel pump problems and the fuel pressure I am told is fine. So I doubt it is the fuel pump.

Oh, and the IAC valve assembly is relatively new.

Of course I realize it may just be the old age of the car and numerous problems and maybe its time to junk it. But at the same time if the problem(s) can at least be positively identified that will help me make the decision as to whether it makes sense to fix it or not.

Any thoughts on things to look at now?

Have you replaced the timing belt? 165k is way, way overdue.

Doesn’t have a timing belt. Has a timing chain.

Have you by any chance had all the vacuum hoses checked. This would affect at least affect the rough idle.

You have to do a compression check now. It may tell you where the burnt exhaust valve is.

Yes all the vac lines have been checked and are good. Will do a compression check.

Would you mind letting me know cost they charged you to replace the cat? I’m told my '99 OHV V6 3.0L is “abnormal” & will cost >1k to replace. Am trying to find folks w/similar experiences w/codes & cats so I can make a better informed decision about what to do w/my car.

The aftermarket unit I bought for my car was $250.00 or thereabouts and I did the swap myself.