Is it safe, for the sake of fuel economy, to make part throttle light load cruising afr's to be higher, much higher, than 14.7 like say more than 16:1??

 

No can do.

Our computers are not designed to read AFR, but crosscounts of the switching above and below 450 mv on our O2's. If the crosscount differs from optimum, the computer adds or subtracts fuel until this crosscount is acceptable.

Ben

 

what about in open loop?

 

I suppose you could do that if you want to run open loop exclusively.

 

There isnt a downside to running exclusively in open loop is there? Also what would be a good point not to go leaner than, or would you just have to judge by EGT's and detonation?

 

i run an open loop tune. no problems at all. however in open loop the pcm doesnt require or use the O2 sensors feedback. they are essentially useless, all my O2s do is plug the holes in my Long Tubes 02 bungs. this will require you to invest more time into tuning to get the fueling just right because the PCM wont compensate using the O2's in open loop mode.
The easiest way to lean out your part throttle driving of your car is to use the OPEN LOOP AFR table ( if your running an open loop tune )

if you want to stay in closed loop mode and want to lean outthe car just lower your MAF tables between 15-40 gps by 5-10%. make sure the transitions are smooth or you will notice stumbling

 

sorry off topic, but lt4 fd your PM is full and your email doesnt work.

 

Im guessing the only way to know, in an open loop tune, if the AFR is correct, besides about what the calculations say it should be, is on a wide band, right? Otherwise you can just setup each section on the table to the AFR you want and be done with it and have it atleast very close to what you want untill it does get on a wideband right?

Also exactly how do you know how much you can lean it out, my guess is EGT readings and the knock sensor...?

Thanks for the help guys!

 

??? Wierd well my e-mail is formula94lt1@yahoo.com and ill check my pm's.

 

sent to that mail, seems to have gone through. Pms dont work at all. say cant sent, has chosen not to accept pms..

hope you get my email.
Its been sent.

Let me know if you get it too.

 

Can anyone help me with my last question please?

 

EGT readings or a wideband dyno are the ONLY way to know. spark retard isnt always directly related to lack of fuel so its not a reliable measure when trying to fix your A/F ratio.

 

You can use the O2's and shoot for 450mv when running open loop 14.7. Any changes to get 450, you need to recalibrate the MAF. This takes a LOT of time. I know because I did it.

Every car is different and you need to research this because personally, I have never gone above stoich.