AFR says YB running lean then not

[RS Eskie]

Hey all, ok so the engine has all the gear for 300hp, I have recently had a stage 2 upgrade to the turbo, bigger compressor wheel and turbine wheel into the T3 housings, at a recent track day on 19psi I believed I was running out of fuel as on full load after a lap or so the engine would basically cut out so I would back off and it would be fine as long as I didn't hammer it again. I turned the boost down to around 12psi and no problem full load around the track happy days. I know the lift and fuel pumps weren't up to it now due to researching their flow rates. So I have installed a new carter lift pump 72gph and main pump is a walbro 220ltr per hour, new crank sensor (as I heard this can cause cutting type issues), the fuel pressure is 52psi with the standard cozzy regulators vac pipe blocked and at idle it reads 42psi with the pipe on the regulator which is normal as it is a rising rate type?
on first start up at cold the AFR is in the red 22.4, sometimes if I rev the engine it would read around 11.8-12.3 in the green, then even with the the engine at slightly higher revs it will shoot back to red! I have recalibrated the AFR sensor and refitted just in case but no change, sometimes it will be in the green after initially reading red and we do this dance all over again! Doesn't matter if the engine is hot or cold it still reads between red and green. WTF is going on? I am lost at what it could be! Could the water temp sensor cause fuelling issues?
Cheers Jonny

[Erikmex]

Sometimes the Afr on a wideband will show off the scale lean when it's running way too rich, the lambda probe gets flooded which stops it working, I had the same issue with mine and it was due to the probe position being too low in the exhaust, ie it sat between 3 and 4 o'clock, I rotating the exhaust so the probe was around 2 o'clock and it cured the problem, if it's too low liquids collect on the probe.

[RS Eskie]

Thanks for the reply Erikmex, the sensor sits in the 12oclock position for that very reason so it doesn't collect fluid, it looked a bit sooty but not clogged, I only wiped the outside as not sure whether to spray brake cleaner or degreaser inside, it was in the exhaust when the T3 let go before the rebuild. I have had the car out on track so would expect if there is any oil in there it would be toast by now and not be an issue?
What is a good AFR reading at idle for cold and hot?
Really needs a probe up its butt to eliminate the AFR sensor

[stevieturbo]

What wideband are you actually using ?

And has it ever displayed correctly ? Presumably the engine runs as normal ?

[RS Eskie]

What wideband are you actually using ?

And has it ever displayed correctly ? Presumably the engine runs as normal ?

Hey mate, it is an Innovate MTX-L. I believe it had been reading perfectly before I did any work as on start 11.8 to 12.7 ish and when driving at 55kph it would be in the orange range 14-15 and under load in the green.
I haven't managed to drive it as yet since the AFR meter has been reading strange, but it will idle nicely when I find the best posi for the CO screw and sometimes the AFR would read between 11 and 12 ,give the throttle a few blips and garage smells fueley. Are there any other sensors that could be causing it to run rich and then lean?

[stevieturbo]

All manner of things could affect fueling.

Whether MAP sensor, TPS, temp sensors etc etc.

Innovates do have their problems and sensors dont generally last that long with them, but the MTX should recognise a failing sensor and give an error warning.

If you're idling between 11-12, no wonder the garage smells fuely, as that's rich as feck for idle.

[RS Eskie]

ok cool thanks, I will adjust the CO till its in the orange around 13-14 under idle,if it will read it. I had it in the upper 12 and the idle was nice but it's started hunting with the readings between 11-12 after I was tinkering to see how it affected the AFR and if it would change readings. Hasn't come up with an error except when I disconnected the sensor and recalibrated it as per the manual, I checked all of its wires just in case but no obvious damage to them. Can you spray brake cleaner or degreaser in the sensor to clean it?
I was told green is good under full load or should it be 14.7 which I believe is the optimal AFR?
Reason I asked about sensors is that the blue sensor at back of the head and the TPS is about the only non new sensors I have replaced due to issues that have cropped up during the years.

[stevieturbo]

Stioch, displayed ias 14.7 is regarded as the cleanest, nothing to do with optimal. "Optimal" is a variable depending on what you want the engine to do.

At full load, again this will vary from tuner to tuner, engine to engine etc, but if it's low 11's it should be quite safe for a turbo engine. Some will want richer, some leaner. Again it varies.

If you're much higher or into the 12's etc on boost IMO do not run the engine under load until you can have it checked out.

[RS Eskie]

Sometimes the Afr on a wideband will show off the scale lean when it's running way too rich, the lambda probe gets flooded which stops it working, I had the same issue with mine and it was due to the probe position being too low in the exhaust, ie it sat between 3 and 4 o'clock, I rotating the exhaust so the probe was around 2 o'clock and it cured the problem, if it's too low liquids collect on the probe.

After reading what stevieturbo has said about it running too rich your idea of it reading lean might be on the money mate thanks. Will clean the sensor and give it a run down the road.

[RS Eskie]

Stioch, displayed ias 14.7 is regarded as the cleanest, nothing to do with optimal. "Optimal" is a variable depending on what you want the engine to do.

At full load, again this will vary from tuner to tuner, engine to engine etc, but if it's low 11's it should be quite safe for a turbo engine. Some will want richer, some leaner. Again it varies.

If you're much higher or into the 12's etc on boost IMO do not run the engine under load until you can have it checked out.

Wicked mate thank you for the advice,really appreciate it

[LAWRENCEM]

If you have fitted a better turbo etc it will flow more air so potentially you will need to remap the entire car to make it work properly but as it sometimes is green sometimes red I'm guessing your sensor or the earthing of the wide and control unit is faulty

[RS Eskie]

That's a good point too, I will check the wiring

[RS Eskie]

Ok so, I believe I have eliminated the AFR sensor as once the engine starts getting warmer it will read more into the green/yellow upper 12-13 range. Went for a run and it hangs around anywhere between 15 & 16 odd, when I stop it reads 13ish and idles nicely. But under load she's in the 14's I am going to put the fuel pressure gauge in and up the fuel pressure to 60psi and see what that does.......still doesn't explain the cold engine AFR readings, it couldn't be fuel pressure as it idles nicely when hot, there isn't that much more fuel being dumped in when cold compared to warm is there?

[LAWRENCEM]

Yes loads more it's quite surprising really sounds like it needs remapping for the new turbo

[RS Eskie]

Yes loads more it's quite surprising really sounds like it needs remapping for the new turbo

Thanks for the help mate, appreciate it, I will get a pro to take a look ��

[Graham]

yes cold start will chuck in a HUGE amount more fuel, often 5 or 6 times more

[RS Eskie]

Thanks Graham, never realized it would be so much fuel compared to normal operating temperature amounts.

[RS Eskie]

Ok, so to update and close off this thread i have found the issue and the engine sensors weren't the problem
It was the Lambda sensor after all due to the car running rich it had clogged it up so i replaced that and have now got the readings back, i have changed the O2 screw so at cold start idle it is now in the high 12's to 13 and under boost it is in the 11's! If anyone thinks the cold start should be leaner or richer then let me know please. And thanks for all your help

[Erikmex]

Good stuff, they are common for that I had the same issue a while back

[katana]

Your install but personally i'm not a fan of rising rate reg's especially with boosted applications. Seen more than a few fail with dire consequences. Why not use a std. boost referenced regulator and map the fuel against MAP? Fuel pump runs at a constant pressure / delivery so better for it also?