Air Fuel Ratio Tuning? Let's get technical, technical, I want to get technical...

[ra23celica]

Let's set the scene:

Car is finally running somewhere near where the factory designed it to be, but its running rich under all throttle conditions, at least 10.01 AFR because that was the limit of the sensor on the dyno, and the numbers did not get better than that.

So, you can turn the AFM wheel clockwise to get a little leaner, but you worry about going too lean and the motor goes boom...

Is an Apexi SAFC or SAFC II (and a dyno for tuning) worthwhile? The SAFC II adds throttle position readout along with a knock-sensor 'alarm' when that happens, but is it that much better than the first series? Who has worked with these things in real life and has some feedback on them?

Finally, wideband O2 sensors that give you the reading at the time - are they good? I imagine they would help with SAFC tuning but once that is done, do you touch it ever again? Are they a poor substitute for a dyno run?

Thanks,
Mitch.

[30psi 4agte]

youll need to set the scene a litle more than that!!



What car/ motor?

How much boost / mods?

if its factory ECU you should be looking to solve why its running so rich.

[chris davey]

yes wideband o2's are very useful. Basically, you can continually fine tune your car for different conditions if you wish. As well as this it is MUCH easier to diagnose problems. ie. car was idling fine and would then just die. Watching a/f you could see it just slowly went leaner and leaner until it died. So you then check everything fuel related. Otherwise, you could be searching in the incorrect areas.

No idea about AFM tuning though.

[ra23celica]

It's an RA23 with a 1G-GZE from a 1988 GS130 Crown, except the ECU (and igniter, FWIW) came from a 1988 GX81 Chaser. Thanks to Witzl's wisdom about 12 months ago, I understand now why just any AFM is not good for any ECU, even when the engine is the same. I know I should have the same 'everything' from the same car, but its just not possible in this case.
Its all standard and factory and sees 10psi.
I have spent something like 18 months chasing a lack of power problem which turned out to be cracks in all 3 coil packs, which, under load saw the sparks exiting stage left rather than via the plugs for cylinder's 4, 5 and 6.

[30psi 4agte]

its not something smple like a blocked starving the motor for air?

too much fuel flow/ pressure. what pump u using?

what AFM were u going off? the dyno one or your own/.
could be a stuffed sensor.

sorry about 20 questions m8

[gearb0x]

I dont know how much paying someone to tune an SAFC costs, but i just finished building and testing my WB02 kit from wb02.com on my Mr2 and it works like a charm. 225$ for the kit and 90$ for the sensor, you cant go wrong

As for how my stock 4AGZE ecu runs, under load at high RPM it runs at 10:1 and dips over that every now and then (10:1 is limit of my sensor too). When idling and cruising it runs at near exactly 14.7. When you stamp it from low RPM it just gets richer and richer till it hits ~9-10:1. Just saying this as an idea of how toyota ecus of the era work

So if your ecu is running 10:1 at ALL conditions there is seriously something wrong, if its just under high load its normal There are lots of differeing opinions about SAFCs on toyota AFM motors. Apparently when u stamp it the AFM flap sticks open and stays open making tuning with a sender bender hard. Not saying it cant be done, but personally id rather go aftermarket. That said there are plenty of ways you can lean out your motor without going to the extent of aftermarket computers, and if your worried about adjusting the flap maybe a WB02 sensor isnt such a bad investment

[S.W.A.M.I.]

those AFR's are a bit too rich.
I dont know if you all have stock ecus or what tricks have been done to your cars, but generally crusing you should see an afr around 14.4-14.8 , idle can be from 14.5-15.8
high load probably 11.7-13.5 , acceleration enrichment should be no richer than 10.5
never test how lean this can be.

[ra23celica]

30 psi 4age,
No worries about the 20 questions mate!
I don't believe I have anything blocked that effects the air flow.
Fuel pressure checked at 38psi, the pump is an external Bosch electric unit.
The AFM is the original GS 130 Crown unit.
I have replaced most of the sensors in the car, including a new single wire O2 sensor.

Gearb0x,
That is eactly why I am thinking of a wideband O2 sensor myself, to save on tuning costs, as I will be paying about that much each time to get on a dyno. Which kit did you get from WBo2 please?
I don't doubt what you are saying about AFM's at WOT, and as long as I am not too lean then I am not that concerned, but AFR of 10 is too much for that condition. Its at idle and light throttle I really want to sort out.

SWAMI,
Thanks for the info here mate, its given me some targets to aim for.

Cheers,
Mitch.

[JustCallMeOrlando]

The question I raise Mitch, when you say it's rich at all throttle conditions, did you mean under 10:1 (i.e. really rich) at all throttle conditions? If so, I wouldn't be bothering with an SAFC etc. until I found out the problem, the car wasn't tuned like that from the factory, it might dip under 10:1 on WOT, but should never on part throttle or idle.

As for the differences in AFM's, if it's anything like the 1GGTE ones (which would only make sense) then it shouldn't matter what version you used, and even if it's a slight bit wrong, it's not going to make it terribly rich everywhere.

In general, you can tweak the AFM a little bit to no real detriment. My car has the AFM tweaked 3 notches tighter. On the dyno, it still spat out perfectly fine (although at WOT it still dipped under 10) AFR's.

The wideband kit will be perfect for future stuff, but it's not going to solve the immediate problem.

[gearb0x]

im using the DIY 2E0 Kit, the intergrated screen brings the total cost down. I wouldnt recomend assembly for anyone who isnt experienced with kits though. Most of it is fairly straight forward and its not THAT hard. but it is easy to stuff up. i think its around 500$ for the assembled and ready to go kit w/ sensor

[chris davey]

My 2c.

I have the 2eo kit from www.wbo2.com. Didn’t put it together as I suck at electronics. Does everything I need it to Love the datalogging! I got this as I always have laptop connected. There are newer fancier versions out now though. Can’t go wrong with www.wbo2.com IMO Was close to $500. Well worth it when dynos costs $150+/hr

Chris

[ra23celica]

Thank you everyone for your input, much appreciated.

JCMF, looks like we have a rich running problem to track down, but I want to get some more data on idle and part throttle running conditions just so I know what numbers its producing and what improvements can be gained.

Thanks.
Mitch.

[gixer]

We use an Autronic WBO2 on our dyno and my findings are very similar to S.W.A.M.I's findings with regards air/fuel ratios. 10:1 is definately too rich and not productive for BHP even turbo. I find NA A/F ratios hover in the 12.5-13.5 band depending on motor, honda's produce max power at leaner mixtures than other NA motors, 20v's in the low 13:1's. Turbo motors produce best power in the 11.5-12.8 band, again depending on the motor and power being produced. But these are just my findings and may differ from others.

[82MKII]

Chris/Gearb0x,
where do you mount the sensor with the wb02 kits?
Is it in the same location as the stock O2 sensor (in which case what signal do you give the ecu) , or can it be just shoved up the tailpipe?

Peter

[gearb0x]

Well i wanted to permanently mount mine when ever i was using it on my cars (but im going to make a tail pipe probe for other cars when i get around to it for friends cars). So long as its before the CAT its ok, some people say after the cat is ok but thats a whole different story and not for this thread. Since the sensors are heated they dont need to be near the headers so i mounted mine down stream in a place where it was easy to install and remove on my Mr2. The general consensous is to mount it above horizontal (stop moisture getting in the sensor) and if u can at around 30 degrees to the vertical (appartly u can heat soak the sensor, but not sure about that one). The stock toyota 02 sensors have a flange where as the Wb02 ones are screw in, u can make an adapter but it was just as easy to weld in another mount in my exhaust