98 Ford Explorer 4.0

[Locomechanico]

My explorer is running really rough. I have spark on all my cylinders however I have 6 engine codes. How can it run lean and rich at same time?

P0301 cylinder 1 misfire
P0302 cylinder 2 misfire
P0303 cylinder 3 misfire
P1131 lack of ho2s11 switches. Sensor indicates lean.
P1132 lack of ho2s11 switches. Sensor indicates rich.
P1151 lack of ho2s21 switches. Sensor indicates lean.

How do I narrow down which oxygen sensor is failing? Or is this problem something bigger?

 

[2000StreetRod]

probably not the sensors

P1131 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1
P1132 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Rich - Bank No. 1

I doubt that your problem is with the O2 sensors. When in closed loop the PCM cycles between slightly lean and slightly rich. The P1131 & P1132 DTCs indicate that the PCM is not able to see the cycle limits being achieved as reported by the O2 sensors. The misfire codes on all bank 1 (passenger side) cylinders make me suspect a combustion problem on that bank. Misfire is due to ignition, fuel or compression problems - most likely to least likely. Since only all three cylinders in bank 1 are misfiring I doubt that you have an ignition problem - waste spark systems pair a bank 1 cylinder with a bank 2 cylinder. You could have a blocked bank 1 fuel rail but that rarely happens. There is a wire that provides power to all three injectors in bank 1 which could be broken but that is also rare. I suggest that you perform a compression check on bank 1 cylinders.

 

[Locomechanico]

Streetrod

Thanks for the great input buddy. I'll have to rent a compression tester and check it out. Which cylinders am I testing and what if one reads low?

 

[2000StreetRod]

1,2, & 3

Since there are misfires on all 3 cylinders in bank 1 I suggest testing them. Examine each plug when you remove it.

Which engine do you have - OHV or SOHC V6?

If the OHV, you could have a blown head gasket. If the SOHC, you could have a slipped timing chain. Hopefully, the compression test results will be good.

 

[Locomechanico]

Check in

I'll be getting the compression tester tomorrow. I'm pretty sure it's an OHV.V6. I replaced the upper and lower intake manifold gaskets on it about 4 months ago. But this problem has been oncoming for at least six months now. Whatever it is has gradually worsened. Come to think of it I am having difficulties keeping my heater going. It seems to lose coolant. But if it was a blown or leaking head gasket wouldn't I have coolant in my oil? My oil is good.

 

[lobo411]

I'll be getting the compression tester tomorrow. I'm pretty sure it's an OHV.V6. I replaced the upper and lower intake manifold gaskets on it about 4 months ago. But this problem has been oncoming for at least six months now. Whatever it is has gradually worsened. Come to think of it I am having difficulties keeping my heater going. It seems to lose coolant. But if it was a blown or leaking head gasket wouldn't I have coolant in my oil? My oil is good.

No. I've had two blown head gaskets so far: one that was just leaking (replaced it before it blew completely/disabled the car) and one that blew completely/disabled the car.

I never had coolant in the oil. Even in the one that blew completely, with clouds of white steam coming out the tailpipe, I never had coolant in the oil.

 

[Locomechanico]

Real quick

I just rented the compression tester. it says to check compression by bumping the engine. I thought we had to crank the engine.

 

[2000StreetRod]

compression testing

I usually crank the starter 10 revolutions (5 compressions) for each cylinder. By then the pressure has usually increased to maximum.

 

[Locomechanico]

How much compression should I be reading? Cyl 1 (50psi) cyl 2 (55psi) cyl 3 (55psi) cyl 4 (30 psi) cyl 5 (60 psi) and cyl 6 (60 psi). Is that right or this pos rental tool missing an oring or something. Very aggravated!

 

[2000StreetRod]

way low

The compression should be about 180 psi for the SOHC V6 and about 165 psi for the OHV V6. Check the 8th digit of your VIN if you don't know for sure which engine you have. The digit is an "E" for the SOHC and an "X" for the OHV.

 

[Locomechanico]

Its vin x. OHV. What is causing such a low compression on both sides? I rechecked my codes today and there was another one for random misfire.

 

[BubbaFL]

Its vin x. OHV. What is causing such a low compression on both sides? I rechecked my codes today and there was another one for random misfire.

Test the compression test tool on another car known to be running well (ust one cylinder should be enough).

If it reads low there, something is wrong with the tool... otherwise, it sounds like you've got some significant problems.

 

[junkbuzzard]

from what I read , sounds like blowen head gaskets, being that low both sides. we use to do wet, dry, to rule out the rings. I jumped a timing chain once on a dodge and bent all the valves on a 318. I had a 300 6 that cracked 4 pistons that had compression that low too, good luck

 

[Locomechanico]

Sometimes when I'm accelerating it feels like the engine hangs or something. It literally moves the driver forward. Doesn't do that a lot but enough to remind you there's a problem.