Hello,

At the end of November my wife and I picked up a 2002 Sable OHV with just over 126700 miles on it.

Made a few mistakes on this one and have been troubleshooting it for the last couple of weeks.

Wife got excited over this car and it had been a month since my 94 sable had been totaled. Needed a car and after looking around, got tired of looking and she bought this one. I messed up by not checking things out. I made many mistakes on this one and if I had done my part, we wouldn't have bought it.

Anyway...

20 miles down the road after purchase the heater stopped working. Heater core had clogged up and needed flushed out. Easy fix.

Next day wife complained car was running a bit rough. I checked the oil level and air filter. Oil level was at the add mark and air filter was very dirty and at one time a mouse was living in the air box. I added more oil, put in a new air filter with no change in idle and roughness. The car did have a miss in it when we bought it. Was told that it had new plugs, new coolant, oil change (all a bunch of bull and I should have known this).

Cleaned the MAF sensor with no change.

I ended up getting the following DTCs:
P0304
P0305
P0306
P0300
P0316
P0175
P0174
Code for misfire during first 200 rotations came up several times when my wife was driving the car. Cleared these codes to see if they would come back and they did within just a few drive cycles.

Oil low pressure light started flickering at idle after reaching operating temperature. Ended up running some seafoam through the crankcase and doing an oil change. It has been about 1100 miles an no low oil pressure light as come back on. I did a manual pressure check before changing the oil and it would not go above 35PSI at 2500RPM. I have not checked it since the oil change. Engine sounds fine other than a constant misfire.

Checked the plugs and found they had been gapped at .060 and not .042. Seems the plugs had been gapped for DOHC and not a OHV engine. Gapping to .042 took care of the misfire first 200 rotations, P0305, P0306, P0174 and P0175 codes. Still had code P0316 and P0304. Old plugs NGK TR55s. New plugs Autolite AP104.

Checked the coil and it tested good. Checked resistance on spark plug wires and the shortest wire had a 2500+/- ohm reading. All other wires tested with low resistance. Testing a new set of wires, shortest wire was 6000 ohms. All new wires as of yesterday. Cleared the codes and still get P0316 and P0304 codes.

During each of my tests I would reset the ECM by disconnecting the battery for 30 minutes. Still no changes as far as P0316 and P0304.

I used my UltraGauge scan tool to check the status of the O2 sensors and Long Term Fuel Trims.

Bank 1 O2 1 = .105 to .755
Bank 2 O2 1 = .360 to .860 (This bank has misfire on #4).

Bank 1 O2 2 = .805 to .830 (slow response appears normal)
Bank 2 O2 2 = .080 to .565 (fluctuating every second. This bank has the misfire on #4).

Long Term Fuel Trim Bank 1 = -3.1
Long Term Fuel Trim Bank 2 = -8.6

Not sure if this matters, but when in park and at 2500RPM LTFT goes to 0.00 on both banks.

Yesterday I did a check of the fuel injectors (hoping I didn't have a bad cylinder).

#4 injector disconnected, no noticeable change in engine speed or misfire (roughness).
#5 injector disconnected, engine idle speed changed, engine stumbled and more rough.
#6 injector disconnected, engine idle speed changed, engine stumbled and more rough.

Listened to the injectors using a long screwdriver to hear them. #4 sounded dull compaired to #5 and #6.

Today I removed the injectors from Bank 2.
#4 is a ford fuel injector. Has a 4 port nozzle.
#5 and #6 are a Chrysler fuel injector made my siemens and have a single hole in the nozzle.

Swapped #4 with #5 and comfirmed misfire is now in #5 cylinder and not #4. Now have codes P0316 and P0305.

Why would a Chrysler fuel injector be in a Mercury Sable? Four of the injectors appear to be Ford (Red/Brown tip) and the other two are the Chrysler (Blue tip).

I am hoping that a replacement injector will rememdy the problem. However, I do not know if the misfire is due to the flow rate differences between the Ford and Chrysler injectors or if the Chrysler injectors are acceptable to use and the Ford injector is faulty. All the nozzles look clean to the naked eye but can actually be dirty. I did run two tanks of fuel injector cleaner thought the tank prior to this with no change in engine sound/feel.