So I've had O2 codes for a while and I was waiting for some cash to do the whole high mileage service posted by Discomike. About a week before ordering ALLLLLLLLL the $700sum odd dollars (probably more, but don't want to think about it) of stuff on there, I started getting misfire codes on bank 2 P0302, P0304, P0306, P0308, along with P0300, and P1300. It runs like ****. The O2 codes that I currently have are P0150, P0135, P0155, P0141, P0161, and P0140.


Things Ive done to fix it to no improvement.
Replaced plugs and wires. Both of which are recommended on this forum, but don't want to name because I don't want to hear the debate. Anyway, nothing changed from my old plugs and wires, so obviously not the issue.
Cleaned Throttle body
Cleaned IAC valve
Seafoam service (vacuum line and gas tank)
New air filter
Cleaned MAS
Checked for intake leaks with the old fashion carb cleaner sprayed around hoses and other places while engine is running. seemed fine.
Dropped the Cats from the Exhaust Manifold and drove it to see if I had a plugged converter on bank 2... (I cleared codes before test drive) Still got misfires and same codes. Bolted them back up.
The oil and coolant have nothing funny or off about them, oil smells and looks like oil. Same for coolant. coolant level stays good.


Going to replace the O2 sensors today, but I have my doubts that they would make a whole bank misfire. COULD THEY?????


Next would be coils (but again, why just bank 2 when bank 2 gets spark from 2 different coils???)


Need to check fuel pressure but haven't looked up how yet.


No obvious signs of a head gasket or cracked block.


I have probably done other things to check but cant think of them now.
Any tips or ideas would be a big help.


My Rover is no beauty queen and not perfect in any way. It has leaks, 3 amigos, other small issues but I love it and want to get it back to the way it was or better. Please help if you can. Thanks in advance =)

 

I bet your O2 sensors are the problem

I think low fuel pressure would effect all cylinders, but here is how to do it.

To do a fuel pressure test:

1) remove to rubber seal on the back of the fire wall.

2) unclip the wire harness from the firewall clips

3) With those 2 things out of the way you should be able to look behind the upper manifold (from the pass. side fender) and see the shrader valve.

4) take a fuel pressure gauge and hook it up to the valve

5) start the car and take a reading while it idles

6) Turn the car off and wait 20-30 minutes and watch how much the pressure drops.

 

You have a lot of heater codes for both banks listed. I don't see any cmp, evap or MAF codes so it's unlikely but check fuse #2 under the hood (controls your O2 sensor heaters, CMP, evap valve, and MAF). The sensors themselves are probably reading but since the heaters are non functional you're probably getting very inaccurate readings.

As for a sensor going bad causing a while bank to misfire, that would absolutely be the case as the fuel trim on that side is based on the sensor on that side, if it is picking up values, but off by a lot, it could cause misfires on any of the cylinders on that side.

Coils wouldn't cause a side to go out since each pack has 2 of each odd and even cylinders. If a coil were bad you'd have misfires in either 1,4,6,7 or 2,3,5,8.

 

Thanks for the replies so fast... I just started the O2's and the bank 2 sensor 1 o2... the connector is full of oil probably from a leaky valve cover. I don't have a gasket set at the moment and I need my rover to run so I can work to spend money on the rover... (what a fun circle) anyway, is there any way to seal up the connector better so I can put the o2's in now???

 

you can try and wrap it up with electrical tape to keep the oil out as a temporary fix.

 

Fill it up with dielectric grease so it keeps out the non conductive fluids (which is pretty much the point of dielectric grease).

 

I have no dielectric grease at the moment It's like the only thing I don't have in my shop. Ive heard that Vasoline works?

 

A buddy of mine JUST TODAY told me about a DII that had a failed catalytic converter (after some other problem previously most likely, resulting in poor A/F ratio that fried / clogged it).

In such a condition, you'd get a misfire on everything upsteam of that cat

 

I'd just tighten the VC bolts and drive it to get some dielectric grease. A trip to the store wont cause the new connectors to break all over again. If you're losing oil THAT fast you have bigger issues to worry about. Besides, Vaseline has MUCH lower heat tolerance and will run right out at high temps. Also it's really only suited for lower voltage applications.

Edit to address EstorilM: A failed cat shouldn't cause a misfire since the post cat (and therefore ONLY) sensor has absolutely nothing to do with fuel trim. It is emissions only. A lot of his codes are also heater related but lacks the other sensor related codes so there's a good chance something is being read, but it is incorrect due to the malfunctioning heaters.

 

So I got the O2's done... all 4. Good news, The misfires seem to be gone "for now". BUT (and that's a big but) I still have codes, and New Codes... yeah me!!!!!!


No misfire codes at all.... Awesome!!!!
Now I have P0171, and P0174. System lean on both banks... GRRRR
Along with those my brand new O2's are throwing...
P0130
P0140
P0150
P0141
P0161


WTF???? This sucks the big one!!!! But I will get to testing tomorrow if I have the time before work. You guys have any tips on what to test besides the normal? ie, intake leak, voltages to the O2's, OHM tests of the O2's. etc. Any good places to start? I believe the P0130 & P0150 maybe the connectors and need a better cleaning. Any Ideas Help. Thanks again