Question about AFR's

[WhininZ]

Ok.

Stoich is 14.7:1, correct?

Anything richer is a lower number, right?

And anything higher is a leaner number, correct?

So me running constant 12.2-12.7 in boost is good??

[Bill@HPTuners]

correct remember its called an AIR to FUEL ratio for a reason

14.7 parts air to 1 part of fuel

as compared to say 10 parts of air 1 part of fuel which would be richer.

Depending on how much boost your running 11.5-12.4:1 is about the norm really...not much leaner then that.

[mgm1979]

to each his own...but 12.2ish in cold weather, 11.2ish in warmer weather.

[Julex]

11.8 in all RPMS and I love it, same as my buddies which is set to 12.1 and he has more mods . But could just be driver. Test them out on a dyno and that will kill all doubt but stay away from leaner then 12.5 especially with smaller then 3" pulley.

[strider]

so should it be around 12 for any amount of boost including under PE? or should it be scaled from 14.7 at idle to 12 at full PE?

[Julex]

14.7 is for your daily driving afr, 12 is for PE only. 12 afr daily driving would cause major gunking. Good luck!

[strider]

so when I supercharge the car I should tune at 14.7 for daily driving? even when I get a little boost happening under med acceleration?

My other problem is that I can't set the afr commanded. Even when I set PE on full time at 14.7 and a 1.O multiplyer. I only get a afr commanded LO res of 14.0. at times it will move into the 13's. Also when I turn on the AC it drops from 14.0 to 13.0.

How do I control the afr commanded to be 14.7 all the time?

[TotheNthRPM]

shoot for a 14.7:1 ratio for normal driving

hell you could probably go up to a 16ish a/f ratio for daily driving. just couldnt get on it and have to pull some timing. i saw a tune from a cobalt ss that had its stoic af at 15.5:1. anything ispossible with some work or course.

[Julex]

But that is just plain stupid to run like that. Could be dangerous on the engine, and it's a COBALT SS not a Honda Hybrid... You buy these cars to drive fast, not conserve gas.

Also you said 14.7 pe.... That is NOT a good idea AT all, again is very bad for you engine, keep pe ratios at 12 or lower. Your PE has nothing to do with daily driving until you get on it. Your low res afr will bounce around commanded due to adders, take out fuel adders ( piston protection, COT, DFCO, etc.) anything that adds additional fuel except PE fueling.

[WhininZ]

Set your base AFR vs ECT under Fuel Control->Power Enrich

If your boosting set it around 12-12.5, if N/A set it around 13.5ish.

Set your PE delay to 0

Set your mult vs rpm to all 1.0

See if that works.

[strider]

I tried the following for VE tuning and my Commanded AFR still will not go past 14.0. Can anybody tell me how to change my AFR commanded to 14.7?

[WhininZ]

Your Closed Loop Enable ECT vs Start-up ECT is whats making your commanded afr 14.0

At idle, my commanded AFR is 13.50 when I'm tuning. When I have the ECT vs Start-up ECT table set normal, it's 14.6
So try that out, set your Closed Loop tables back to stock and get back to me.

[strider]

In the guide I posted (originally posted by shifted on the J body forum) it states to turn of closed loop. That way the fuel trims will be turned off. then it says to set my afr via the PE tables. However the car when warmed up jumps to 14.0 even though I have it set for 14.7.

So what am I doing wrong? Should I ask tech support if their is a table missing or something like that?

Or am I stuck with it and I have to change my pid for afr error% by adding 0.7 to the commanded afr sensor?

I have been trying to figure this stuff out over the past year. I finally get somewhere with the PLX and then this happens. LOL

[Russ K]

These cars don't yet have the open loop tables in the editor. Try setting the PE to 0%, and the base AFR to 14.7. Also set the Multi vs Rpm to 1.00. This is how to tune the V6 cars in open loop.

Russ Kemp

[WhininZ]

Well, when your using Shifted's guide, the commanded AFR is lower than what your actually command. Like I said, when I'm at idle NORMALLY I would be at 14.6 AFR, but when I have all those tables set for tuning it the commanded AFR is 13.50. I don't know why, but it is. So you will just have to deal with it. Why are you setting your AFR for 14.7 in PE tho? I'm just curious, even if your N/A you would want to be in the 13.5-14.0 range.

[strider]

I set PE for 14.7 so I can properly tune the VE tables under partial throttle conditions. Once that is done then I can reset for wot PE. I just don't understand why I can't force the commanded afr to be 14.7.

I need to figure this stuff out now so when I install the supercharger I can get it up and running a little easier.