Celica - a few questions

Toyotafanboi

first off, i was bobbling along the motorway today and the check engine light came on, car sounded ok and appeared to be driving ok, so i cracked on home (150 miles ish).

just scanned the car there now and got:

P0420 - Catalyst System Efficiency Below Threshold (Bank 1)

cleared the code and it stayed gone over a ten minute drive.

have been noticing a lot lately that it runs a bit unsteady and there is a lot of pinging if under load. i wonder are the two related? possibly not?

doing some amateur research i understand that my engine (Toyota/ Yamaha 2zz-ge) has a compression ratio of 11.5:1 which is rather high and the engine i had fitted was a Japanese model which was intended to be used with 99RON fuel, not the 95 we have here. would this be making much of a difference? i've had a good few Japanese cars before with no issues on 95RON, but i'm wondering should i use an additive in this instance, or could my poor running be associated with that fault code?

morritty

I'm after reading that Maxol fuel is 99RON? then again the interner could be wrong, no harm in trying it if you're near one.

Superwofy

morritty wrote: »

I'm after reading that Maxol fuel is 99RON? then again the interner could be wrong, no harm in trying it if you're near one.

You're thinking of Maxol E5. It was close to 99 RON. They no longer offer it.

The import 2ZZ is indeed mapped for premium (98). That being said, the ECU is equipped with knock sensing (as are most modern engines) and will automatically retard timing if it detects 'pinging/knock'.

The low octane fuel is certainly not helping but is unlikely to be the root cause of your issues. More likely a broken O2 sensor or a degraded Catalytic converter.

Some people use Dipetane to lower emissions. Might be worth looking at that if you just want to try an additive. Won't increase octane rating tho.

MetzgerMeister

In case you're thinking of it, I wouldn't bother with octane booster type products. It takes 10 octane points to give an increase from say 95 to 96 RON. One 500ml bottle of octane boost does increase octane but only by 1 octane point so in order to get from 95 to 96, you'd need 10 bottles.

Things could have changed but that's my experience from when I had the MPS.

PADRAIC.M

From my experience you will need to change the Cat, if your scan tool can read O2 sensor 1 and sensor 2 it's easy to tell if your cat Needs to be replaced

nd

Have had that cat code on my corolla since basically the day I bought it over a year and a half ago. It passed the nct last time with virtually perfect emissions results. Will post the exact readings if I find them.

emissions results

brembo26

isnt it just the o2 sensor around the exhaust manifold? bank 1 being before the cat so its hardly a dodgy cat?

nd

it should be bank 1 sensor 1, or bank 1 sensor 2. If one i'd replace it as it effects the engine efficiency. If 2 I'd ignore it as it's just saying the cat isn't 100%.

HardenendMan

Basically it means that the O2 reading post cat converter is too similar to the pre cat sensor (1). Either you need a cat or a new sensor.

joujoujou

^^ What he said. ^^

Edit:

Toyotafanboi wrote: »

[...]

cleared the code and it stayed gone over a ten minute drive.

[...]

Try this:

- run it for a good while to make engine (and exhaust) hot
- stop, clear the code and run it like you stole it.

From my own experience - it's less likely for P0420 to appear when car's driven very aggressively. And it may not appear at all if car is always driven that way. Obviously, more money would be spent for fuel.

jimgoose

Hmm. Pinking absolutely should not be happening in this day-and-age, surely? My crackpot theory is that the resulting improper/incomplete combustion could be degrading the cat. How's fuel consumption?