Has anybody experimented with putting resistors in the O2 sensor wiring to make the car run richer in closed loop? I know the computer is hard coded to 14.7 AFR but couldn't it be fooled into running richer.

My car runs alot better with lower AFR's at part throttle so I have been running open loop.

 

Somebody must have tried this? Maybe I will be the first.

 

Cant do it. PCM is hard wired for a 14.7:1 aft in closed loop.

 

Annd how does it know that its hitting 14.7?

 

The O2's tell it. That's your answer. Swap out your O2's for a couple wideband LM1's with programable output to the PCM. The PCM is shooting for 450 MV, not 14.7 AFR. You can make 450 MV whatever you want with these O2's.

 

fill in the maf so less air flows... the maf will never know what happened.
the People that say its impossible shouldnt interrupt the people doing the impossible

 

have you ported your maf? if it runs better with lower afrs something must be wrong, maybe you need to recalibrate the maf?
the stock tune is rich at WOT.
all other times it is supposed to be @ 14.7 @ part throttle and idle.

it maybe tuned to be 14.7 stock, I wouldnt say its "hard-coded" as if you cant change it.
Do you have Hp tuners? Its real easy to change your stoichiometric value

 

In closed loop it doesn't matter how the MAF is calibrated. Fueling is adjusted with the O2 sensors through Long Term and Short Term fuel trims. Theoretically, If I could find the right size resistor 450mv could be transmitted to the computer when the car is really at 14.0.

There is nothing wrong with car, it just likes a richer mixture because of the cam and supercharger.

I don't think HP Tuners works with 97 OBD 2.

 

Can you elaborate on this? Have you tried this before? Know anyone who has or where to get info?

 

What about richening up the maf tables and adjusting the min blm to around 120 so that it can't pull fuel beyond that point? If you have a wideband and can set it up, wouldn't this work?

 

Yes I've tried this with my computer and tunercat. When you make the min blm 120 it does not allow the long terms to function correctly. So that means that no "learning" is occuring. This will work but you don't get the benefit of saved long terms. Also it won't hold a steady 14.0 it will fluctuate.

Thanks for the input though.

 

your little resistor idea surely seems plausible

 

Sure. First I need to correct my typo above. I meant to say LC-1 but typed LM-1.

Basically these allow you to replace your stock narrow band O2s with the widebands. They will output an analog "narrow band simulation" to the PCM. But the output is programmable. This is the factory default of the first analog output:



450 MV = 14.7 AFR, a very narrow step-like function close to what narrow bands output, your PCM shouldn't know the difference between this and the stock O2. It should run the same. But you can put any numbers you want in there. Simply subtract .7 from both AFR boundaries like so:



Now 450 MV = 14.0 AFR. Your computer won't know the difference, but you'll be running richer in closed loop because your computer will force it to run averaging 450 MV, and it will correct to that constantly.

They have their Manual online. They also have a message board with some good info--HERE is a thread that talks about doing it the other way for better mileage.

 

Thanks this is just what I was looking for. I still might try the resistor trick.

 

Sounds interesting.. never knew such a sensor existed and always thought the wideband needed a 5 volt power source.