Oxygen Sensing?

[Alex Chardy]

Hello all,

So after replacing all the spark plugs, ignition coils, and fixing a vacuum leak. I have finally gotten the check engine light to go away. But it just came on and the codes it’s throwing are weird. P300 random cylinder misfire and it’s throwing codes that are saying all cylinders are misfiring and the last one is an Oxygen sensing code. Anyone have any clue what could be causing this?

[DBJoe996]

A bad O2 sensor will do that.  How many miles on the car?  There are four O2 sensors, two pre-cat and two post-cat.  If you have access to Durametric, it will tell you which one is not sensing correctly.  Have you checked the harness connectors on the tray in the engine bay?  Maybe one got knocked loose.

[Alex Chardy]

I don’t have a Durametric unfortunately. Maybe I can find a shop that has one that will let me use it there. Car has 34k original.

[DBJoe996]

You can also try your local PCA Chapter to see if a member has Durametric and would let you use it to evaluate your running parameters.  34K is pretty low mileage for an O2 sensor to go bad, but stuff happens.  Having an OBDII reader is worth its price.  Durametric is the best.  i don't know if a standard OBDII reader will tell you which one is acting up...probably just give you a P code for O2 sensors.

 

Remember that the DME is using things like the O2 sensors to determine how the engine is running, and then it makes adjustments on the fly.  The misfires are probably a result of one (or more) of the O2 sensors acting up.  Tackle it first.

[Alex Chardy]

23 minutes ago, DBJoe996 said:

You can also try your local PCA Chapter to see if a member has Durametric and would let you use it to evaluate your running parameters.  34K is pretty low mileage for an O2 sensor to go bad, but stuff happens.  Having an OBDII reader is worth its price.  Durametric is the best.  i don't know if a standard OBDII reader will tell you which one is acting up...probably just give you a P code for O2 sensors.

 

Remember that the DME is using things like the O2 sensors to determine how the engine is running, and then it makes adjustments on the fly.  The misfires are probably a result of one (or more) of the O2 sensors acting up.  Tackle it first.

 

So I have an Obd2 reader. But just not a durametric. I know it’s worth the money but have been spending my fun money on parts. I do have live readings. On the scanner I believe they are the shrtft1&2 and  longft1&2. Is that correct?

[Ahsai]

"the last one is an Oxygen sensing code." <- what was the code in addition to P0300?

[Alex Chardy]

I meant on the live data it’s the 02B1S1

[Alex Chardy]

16 minutes ago, Ahsai said:

"the last one is an Oxygen sensing code." <- what was the code in addition to P0300?

P0300

P0302

P0304

P0305

P1126

P1133

All the codes that are there now. The 6,1, and 3rd went away apparently. And the 2nd popped up

[Ahsai]

What year is your car?

1126 and 1130 means the engine is running rich. Too much fuel pressure or not enough air. Could be the MAF.

Have you made sure all coil connectors are firmly seated? What is the MAF reading at idle with engine warmed up?

[Alex Chardy]

1 minute ago, Ahsai said:

What year is your car?

1126 and 1130 means the engine is running rich. Too much fuel pressure or not enough air. Could be the MAF.

Have you made sure all coil connectors are firmly seated? What is the MAF reading at idle with engine warmed up?

It’s a 2000. I had a CEL telling me fuel was running lean. Changed the MAF and that went away. Give me about 30 mins and I can tell you what it’s reading at. In a live data I did before it was at 5.25. But I’ll check again to make sure it’s same as before

[Alex Chardy]

1 hour ago, Ahsai said:

What year is your car?

1126 and 1130 means the engine is running rich. Too much fuel pressure or not enough air. Could be the MAF.

Have you made sure all coil connectors are firmly seated? What is the MAF reading at idle with engine warmed up?

Just got the reading. 4.5

[Ahsai]

4.5g/s sounds ok. I think the spec is 15~18 kg/hr. May want to check rhe fuel pressure and regulator then.

[Ahsai]

Do the plugs have the correct spec?

[Alex Chardy]

15 minutes ago, Ahsai said:

Do the plugs have the correct spec?

What spec do they need to be? I just put in some Denso Double Platinums. Specs are in the pic.

[Alex Chardy]

I’m gonna take out all the spark plugs and coils  tonight and re install. Maybe they cross threaded. Worth a shot.

[Ahsai]

All spark plugs have specific heat range and other specs and are engine specific.  I'm not familiar your plugs from Oreilly but you should get 99917020791

or Bosch/NGK equivalent. Should be like $5 each.

Edited June 23, 2018 by Ahsai