little deuce overfueling issue resolved.... i think???

[frog_eyed_mk1]

Very interesting, my afr sensors are not reading like yours, but my fuel trims are now operating perfectly staying very close to zero after 40 miles of driving, but the afr sensors reading around 0.65v but are not stuck at the voltage as they were before they also jump around so they are doing something.

Now i did read somewhere that when reading afr sensor live data readings on some scanners they change the voltage of a wideband sensor reading of 3.2v to read like a conventional narrowband o2 sensors.... I guess it's possible this could be happening but im not sure... Please correct me if im wrong with that statement.

Also seems strange as im using virtually the same scanner as you mine is a "maxidiag pro md801" but looks exactly the same, i cant get live data readings through the manufacturer mode so im using the EOBD mode....

I guess I could try scoping the sensors directly as that would give me an actual value....

It will be Interesting when i get it back in for mot retest with the emissions.....

[rainen]

Your MOT emissions will be fine with those trims. Mine sit on similar values. The only thing that did me in last time was the CAT. I had a 200 cell sports cat on and it was not up to the job. Had to go back to the original MR2 cat which even then had to be held at 3000 revs for a time to get it hot enough to bring the readings down. No expert on the scanners so not really sure why we see different readings for voltage. I use the same mode as you. I’m sure we will have some further experts on here that might be able to add some better logic and reasoning.

[frog_eyed_mk1]

Well I've just had an interesting find, friend has a rx300 so I borrowed it, they are a lovely drive :)

Anyway I plugged it in to look at the live data readings with the scanner im using for the mr2, and as you do i am getting reading of around 3.2v from the afr sensors, so it is beyond me why the new sensors on the mr2 are reading differently.....

I think my engine is out of a 1998 Toyota harrier so maybe thats why....

Il should be able to post up new emissions readings by the end of the week, hopefully the cat isn't damaged due to the running issue.... We shall see :omg:

[Paul Woods]

The different ECUs use the AFR sensors at various voltages, I've seen both voltage types, nothing to worry about as long as they are switching and fuel trims are within limits.

[frog_eyed_mk1]

So went in for retest and its good news, it passed..... But the co reading was high so im suspect that the cat has gone, co at 2500rpm was 1.2%

Luckily its a 93 so goes through a "non cat" test with ease.....

Fuel trims are spot on still....

So unless someone tells me the co reading is too high and needs fixing the next job will probably be some light rust treatment in areas....

Thanks again people.

[Paul Woods]

I've noticed an Mr2 CAT on a V6 needs to get super hot to pass emissions, your tester can carry out additional pre heating (basically holding the RPM at 3000 for 3 minutes), they usually pass after that. It could also be the CAT is not as efficient as it used to be.

[rainen]

Spot on Paul. My tester had to go for the 3000 rpm hold to get the cat hot enough to pull the CO2 down which I needed as mine is a 1998. I’ve since taken the shield off and used a titanium wrap to try to hold the heat in better. Will not know if that’s made any difference until the next MOT in March 18.

[frog_eyed_mk1]

So i can now happily report back the car is running perfectly, unfortunately I couldn't make japfest as i was visiting family but i took the car and did 500 fault free miles, the first 200 were mainly motorway and managed to achieve 36.2mpg of normal 70-80 driving without being overly careful which im surprised at, the extended 5th gear is an absolute godsend on the motorway, crusing at around 2500rpm..... I have a few little projects for the car in the future and will be posting on here in a new thread when they are started.... Thanks again twobrutal