1998 lincoln MK V111 56,000 miles/rough running engine

My wife has a 1998 Lincoln MK V111, which is only driven on short (5 mile) trips, except when I take it out for a fast run. About two months ago the amber engine light came on and the car ran rough, as though a cylinder was missing. I disconnected and re-connected the battery, thinking it might be a computer glitch, the light stayed off and the car improved but only for a very short time and then it went back rough driving particularly on tip-in and the light came back on.

I took it to AutoZone who diagnosed it as “Cylinder #2 misfire”. Not knowing much about the complexity of this engine I had a Ford mechanic friend check it with a STAR tester, he confirmed AutoZone’s diagnosis. He checked all the plugs and found the #2 fouled. He then (1) Installed new plugs, (2) Installed new boots (4 of the original boots were broken near the top of the boot), (3) Installed a new #2 Coil on wire, (4) Checked the fuel pressure 20 lbs/sq. in., (5) Checked the vacuum manifold 18 in., (6) Checked the EGR (it’s okay), (7) Checked the PCV (okay). We took it out for a run and it still ran rough except when cold (which is only for about two miles). He had to leave, so I pulled all the plugs (one at a time) and checked them for spark, they all had a big, fat spark. All the new parts are MotorCraft.

I bought a fuel filter at AutoZone and installed it, the fuel pressure checked 30 lbs/sq. in., the tank was almost empty so I filled it with premium gas(I had been using regular for about three months), poured in a bottle of injector cleaner, checked the air cleaner (okay) and took it out on the X-Way, ran it up to speeds of 100MPH, it ran fine except on tip-in and occasionally at steady state. When I got off the X-Way I had to make a Michigan left turn to get back on the X-Way, then a right turn at which point the car stalled and I had to restart it. On the way home on surface streets the car stalled twice, when I stopped for lights. The engine has a slightly rough idle of about 500 RPM in neutral and tends to almost die at tip-in. It idles at 480RPM in drive and sometimes stalls when put into drive, unless given a little gas. I noticed today that when I ran in idle in the garage, a thin stream of water was dribbling from the front of the mufflers.

Yesterday my mechanic friend went to another friend and checked his 1998 MK V111, same vehicle as my wife’s except it has about 25,000 miles. All the pressure and vacuum readings were the same as my wife’s car.

Got a call from my mechanic friend saying that the way the car drove reminded him of 'EGR trailer hitching" in a car he used to own. I decided to try disconnecting the EGR vacuum, plug the line and drive the car. Every time I stopped or slowed down the car stalled, also ran very rough for a short time, after I re-connected the EGR, then settled down but continues in the ‘trailer hitching’ mode.

We are totally bewildered and will appreciate any help. Derrick Ratcliffe

Whats a “michigan turn” whats’tip in’ and whats “trailer hitching”

The terminology is all Greek to me too.

Anyhoo, if the car only dies at idle/low RPMs then you may have a dirty Idle Air Valve. This is especially true considering the car is 11 years old and only has a measly 56k miles on it along with a lot of short hop driving.

If the car dies at speed on the open road, and considering the previously mentioned 20 PSI of fuel pressure which is way too low, it’s possible that a clogged fuel filter could have killed the fuel pump. 56k miles it too young for a pump failure but with a clogged filter it’s quite possible.

Fuel filters should be changed every 15k miles or so IMHO. Before going to CO last year on vacation in my Mark 8 I discovered while doing some basic maintenance that the fuel filter (which only had about 12k miles on it) was partially clogged. The car ran fine but I made the comment to my wife several times during the trip that I was worried about the fuel pump suffering from that filter.
And of course, on arriving back home about 10 at night during a horrible driving rainstorm the fuel pump gave up its life about 20 miles from the house. :frowning:

I’m kind of leaning towards an Idle Air problem and this can occur without setting any codes.