Air Fuel Ratio result questions ? VP SS V8

[92 VP SS]

Hi I just installed an Air Fuel ratio gauge to monitor the O2 sensor and closed loop performance.

Im curious with the results I got.

At idle my gauge displays very rich results; I would of thought it would be in the stoich range ?

At 50-60k cruising in OD where RPM drops down to 1000 RPM I get rich results indicated; I would have also thought this would also be in the stoich range ?

The gauge seems to read correctly in that it will enter closed loop and swing when not accerating or deacellerating. De accelleration indicates lean and accellerating indicates rich as to be expected.

Anyway I was hoping someone might let me know if my results were the same as theirs or if my car is running rich when it should be lean ?

Also when I turn on the ignition 2nd swith the gauge reads dead center stoich from cold which I would have thought it would have read dead lean ?

[92 VP SS]

Been researching this and apparently the ECU will set a .450 V dummy signal to the Oxygen sensor when its cold.

Aparrently idle is closed loop and is set rich at about 12:1 or so and I guess when my car coasts in OD it goes to idle mode and enrichens.

I want to figure out away to lean the idle to 14.7 or so so that when it idles and coasts it doesnt waste so much fuel !! Any ideas ?

[delcowizzid]

all sounds perfectly normal only way you can change it is to buy some ecu tuning gear and tune it or get it tuned

[92 VP SS]

Thanks delcowizzid, glad its normal.. Do the VP V8s run well if the fuel is trimmed at idle ? I was really surprised to see that when I was coasting in OD it was rich as that was where I thought I was using the vehicle economically .

I can definiatly say that the narrow band auto meter gauge I have is great. Its very stable when the the engine is in Open Loop and notifies closed loop by the swings, Im assuming the width of the swing will indicate rich or lean depending on which side it favours when swinging.

I have a swith so I can turn it off also that way it wont irritate me on long drives at night when Im not testing it.

Do you know of any good pre made fuel efficient tunes available in NZ that I could readily buy and just do a memcal swap ?

[delcowizzid]

take the lid off the ecu and tell me what tunes in it now there will be a silver sticker on the chip in the memcal under the blue cover

[92 VP SS]

Hi its DELCO BAP 6945 , that is my standard chip. and I have another chip that is currently in the car that Im trying its by a trademe user based in Australia called TRX100 STAGE 4 GEN VN/VP V8 perf memcal. It noted that it made 17kw over stock but to be honest I dont notice any difference and it doesnt ping even with 91 octane.

Which one do you think would be better for economy? Im currently testing the TRX100 but will put the other back in if it improves effeciency.

[92 VP SS]

edit DELCO BAAP 6945 not BAP

[delcowizzid]

lol most ebay sellers couldnt make a tune if they tried most just buy off other people and copy them could be anything in that tune

[92 VP SS]

Thankyou.

I will remove the chip Im running because its too much of an unknown entity.. Would the DELCO BAAP 6945 standard tune be good ? or is it too conservative in terms of lean burn and spark advance etc ?
Im thinking of increasing the base timing to 14 BTDC and running the standard tune, from what I've read that produces good results ?

If the above does not sound like a good idea could you please let me know where I could get a better tune for economy at idle and coasting but with increased performance under heavyier throttle .

[delcowizzid]

yeah stock tune at 14 degrees will be fine will go better than stock.as for economy a new o2 sensor may help if its been in there a long time

[92 VP SS]

Ok great. Will put the stock one back in and set to 14 and remove unknown performance chip I have.

Ive got a heated 02 sensor that I will install next when I installed the gauge I set up a seperate fused circut to run it off the battery from a switch maybe it will go into closed loop earlier and produce better feedback from the ECU as I have Genie headers and the o2 sensor is only reading of 2 cylinders I assume it wont be as hot as it needs to be at low RPM.

If you come across a really good pre made tune that will be good for me please let me know. From what Ive read the factory tune has too many safty margins built in that affect economy and performance, I also read that they cater to the cat converter a bit and mine doesnt have one.

Thankyou for you advice.

[delcowizzid]

i could probably make something up for it .

[92 VP SS]

Yay that would be great. I drive the vehicle 90% of the time for economy then the odd time give it a bit of gas. I would really love a tune that would maximise economy but not reduce performance, also at wider throttle positions Im happy for it to use fuel for power. At least that way I can control how much fuel I use by my driving style. My email xssol@hotmail.com if you could let me know price etc.
Kind Rgds
Sol