[mtw002]

Sooo it ran good for a while. Now it popped some new codes. The check engine light is illumintated and actually started flashing. It runs fine part of the time then it cuts back and acts like it is missing. Could a fault O2 sensor cause this?

P0161----Oxygen O2 Sensor Circuit Low Voltage (Bank 2, Sensor 2)
P0202----Cylinder 2 Injector Circuit Malfunction
p0204----Cylinder 4 Injector Circuit Malfunction
p0208----Cylinder 8 Injector Circuit Malfunction

They just replaced the PCM last month.

[ajm]

I could be wrong but seeing that its the rear o2 sensor throwing a code I doubt it. The front would be a different story though.

[RyanGT]

Pcm's don't go bad. very often (1 in 10 million). Have you tuned it up? You have misfires on both banks. I would start with replacing the plugs, then move a cop and see if the misfire follows. Just do one at a time, i would swap cop 2.

If the misfire follows the cop. Replace them.

[ModMustang97GT]

the O2 will not cause a miss fire. A miss fire only happens from bad timing. The O2 sensors don't have any part of the timing. They only control the air\fuel ratio. They might richen you up a bunch, but not cause a missfire.

[Matt Cramer]

If the injectors are plugged or not firing, that could also cause a misfire. Also, as misfires usually don't use up the oxygen, they can create a lean reading. So it could very well be your misses are causing the O2 sensor readings and not the other way around.

[RyanGT]

Thats true. I would still check cop's before injectors though. Injectors can be swapped also. And follow the code. Easiest way of troubleshooting cheaply without just buying a set of cops and injectors Just make sure you do one or the other first, not both at same time.

[mtw002]

Its a intermittent problem. The car will run fine then it will run like @$$. I'll swap some cp around and check the plugs while they are out...

[ajm]

Check the coils with a dvom. It doesnt take but a few minutes.

[mtw002]

is that a direct voltage ohm meter?

[RyanGT]

digital

[mtw002]

I'm going to change the O2 sensor. The O2 sensor code came first. There were 2 of them. Then after i cleared the codes and drove home the next day it threw the other codes.

[Trick Tuners]

Originally Posted by mtw002 Could a fault O2 sensor cause this? They just replaced the PCM last month.

No, because the misfire is on both banks, both o2s would have to be bad. Why did they replace the pcm? That is the typical move of a shop that has no idea what the real problem is, and chances are it didn't solve anything.

Originally Posted by RyanGT Pcm's don't go bad. very often (1 in 10 million). Have you tuned it up? You have misfires on both banks. I would start with replacing the plugs, then move a cop and see if the misfire follows. Just do one at a time, i would swap cop 2. If the misfire follows the cop. Replace them.

good advice.

Originally Posted by ModMustang97GT the O2 will not cause a miss fire. A miss fire only happens from bad timing. The O2 sensors don't have any part of the timing. They only control the airfuel ratio. They might richen you up a bunch, but not cause a missfire.

The timing would have to be WAY WAY off to get a misfire. Most misfires are due to lean or rich mixtures. You could add or subtract nearly 20* timing and not get a misfire at idle and low part throttle (BAD idea at wot!!!)

[mtw002]

Originally Posted by Trick Tuners No, because the misfire is on both banks, both o2s would have to be bad. Why did they replace the pcm? That is the typical move of a shop that has no idea what the real problem is, and chances are it didn't solve anything. The timing would have to be WAY WAY off to get a misfire. Most misfires are due to lean or rich mixtures. You could add or subtract nearly 20* timing and not get a misfire at idle and low part throttle (BAD idea at wot!!!)

They changed the pcm because I erased it when i downloaded the codes last time my car took a crap on me last month. It did get 2 different O2 codes the first time i read them. I remember the one but not the other. When I cleared them the only one that came back was the 161 along with the misses.

[mtw002]

Well I found the wiring to both rear o2 sensors pulled out of the sensors. Solder the wires together as a temp fix and it runs great again...So thats a fix until i get my LT and Hpipe installed.