E85 code deciphering

[x-driver]

Apparently the engine adapts to every condition and components and their functioning. It would probably adapt to new O2 sensors with time, but very long time so you have to reset it manually to teach in again correctly. It has to be done via tester.

I don't think O2 sensors would cause rough idle or something like this. Rough idle would more likely be caused by coil plugs, MAF sensor, crankshaft sensor and camshaft sensors. Or some more serious issues.

[Mike6]

Didn't think you had to reset anything after replacing the sensors. I didn't and haven't noticed any difference.

[x-driver]

Didn't think you had to reset anything after replacing the sensors. I didn't and haven't noticed any difference.

Are you talking about O2 sensors or all sensors in general?

Of course you don't have to reset engine adaptations for all sensors, but for O2 sensors you have to.

[Dr. Zed]

Apparently the engine adapts to every condition and components and their functioning. It would probably adapt to new O2 sensors with time, but very long time so you have to reset it manually to teach in again correctly. It has to be done via tester.

I don't think O2 sensors would cause rough idle or something like this. Rough idle would more likely be caused by coil plugs, MAF sensor, crankshaft sensor and camshaft sensors. Or some more serious issues.

Thanks for the info!

Would O2 sensor issues cause misfire errors though?

[x-driver]

I don't think so. I'd replace the coil plug on the faulty cylinder first.

[Dr. Zed]

I don't think so. I'd replace the coil plug on the faulty cylinder first.

I've move two coils around. Didn't move the error code. Sparks are fine too and the car is showing no other sign of misfire. Idles fine, starts up fine. No issues through the gears and gives full power under load.

[x-driver]

So except the fault codes your car runs totally fine? Try another tester for start. Clear all codes, go for a ride and read the codes again with different tester.

If you already did that, what codes you have now?

[Dr. Zed]

So except the fault codes your car runs totally fine? Try another tester for start. Clear all codes, go for a ride and read the codes again with different tester.

If you already did that, what codes you have now?

Done all the above, and still have the same codes.
It's really confusing me. So unless it needs a good run because I only took it for 20 mins as I didn't wana run it too much given the misfire error. In my opinion it's not misfirig but I don't want to wreck the engine if it is indeed misfiring.

[x-driver]

How old are your spark plugs? Did you replace them or just visual checked them?

Have a look for some more vacuum leaks. Secondary air pump is ok?
Was CCV ever replaced?

Bad fuel is also a possible cause for misfire.

[Dr. Zed]

How old are your spark plugs? Did you replace them or just visual checked them?

Have a look for some more vacuum leaks. Secondary air pump is ok?
Was CCV ever replaced?

Bad fuel is also a possible cause for misfire.

I've never replaced the plugs so who knows how old they are..

I really can't imagine it'd be CCV or anything because I'd imagine a sensor for that would throw a code.

Bad fuel might be a shout because it hasn't be driven in 3 months but the check engine light did come on before that 3 month time period. And 3 months really isn't that long for fuel.
And again, I'd expect the car to be struggling under load for most of those things, no?

[x-driver]

Then I recommend you replace the plugs asap

CCV won't throw a code. When it's bad, you might notice increased oil consumption, misfire might happen, some test for CCV is to open the oil cap when engine running. If you notice heavy vacuum when removing the cap, it is believed the CCV is bad.

Not every fault will show under engine load. Some will show when idling or driving moderatly (~2.000 rpm).

[Dr. Zed]

Then I recommend you replace the plugs asap

CCV won't throw a code. When it's bad, you might notice increased oil consumption, misfire might happen, some test for CCV is to open the oil cap when engine running. If you notice heavy vacuum when removing the cap, it is believed the CCV is bad.

Not every fault will show under engine load. Some will show when idling or driving moderatly (~2.000 rpm).

I'll give it a go mate, thanks!

[Dr. Zed]

All sorted, thanks to all that helped me sort this! As always, much appreciated.

[x-driver]

Great! what turned out to be the problem?

[Dr. Zed]

Great! what turned out to be the problem?

Mechanic asked me what the issue was and I explained the EML came on last year and has been since. Told him I'd replaced a section of split piping and both pre-cat sensors. Still nada. He rang me an hour later to say it was all sorted. There was a tiny split in another line that I missed but this wasn't the root cause. He wasn't 100% sure what exactly caused it.

He reckons it was a low voltage at some stage and it wrecked havoc with the ECU. Why this manifested itself as a random engine light on a random day last year and why it was then a persistent engine light for months he wasn't sure.

He also wasn't sure if the O2 sensors actually needed to be replaced but I'd done them the day before I dropped it in.

He cleared all the codes with some fancy reader and all done. He did a health check and smoke test too and said the engine was in perfect health.

So yeah, all done!