Now that I can stare at my A/F ratio as I drive I am noticing things... Wtf is going on here? As I understand it the WOT fuel map is static. I used the Predator to full almost 12% fuel across the 3 RPM ranges at WOT after my tune at PPP. I left (700 feet altitude) with 12.3 to 1 and arrived at 7000 feet with 10.0 to 1. Pulling 12% got me back to 12.0 to 1 and I left things there. My question is this: What else will affect the WOT A/F ratio? I am getting anywhere from 10.0 to 1 to 11.x to 1 lately. The only change I can see is inlet air temperature has risen quite a bit as ambient air temps are 90+ degrees. If my car is pulling timing to avoid knocks I assume I won't burn quite as much fuel and my A/F ratio will go down, correct? I don't want to change anything until I figure out what is going on. I would log data but my laptop is out of commission. That would tell me instantly if it was a timing issue. Thanks for the help!
Jon, The car WILL richen up as the elevation increases. Keep in mind, if you go back down to Sea Level, the A/F will lean out. And yes, weather will play a roll in your A/F as well.
Agreed. I got my WOT A/F ratio back to 12.0 to 1 or so AFTER I got back to 7000 feet. What I am seeing now is an A/F ratio of 10.5 to 1 now without doing anything. The only change that I can see is 90+ degree weather outside. Will heat have that much of an effect?
Ron is right but 10.0 at WOT is just way too rich I think when these are stock they run 11.2 I'm not sure of the negatives for running too rich but I would imagine it would harm some stuff even the obdII sensors
The odd thing is that 2 months ago I was running 12.2 to 1 or so A/F ratio at WOT. When I go WOT now in exactly the same place, 10.5 to 1. I haven't changed a single thing. The only obvious difference is it is 30 degrees hottor outside. I guess my question is what can affect my WOT A/F ratio on these buggys that drastically. I should add my cruising A/F ratio hasn't changed one single bit...this would imply my Innovate probe is functioning as it should or at least as it used to.
Yes, heat will effect it. If you hold the pressure the same, hotter air is less dense. The MAP sensor wouldn't see a change so you'd be using the same cell in the table and the injectors would be delivering the same amount of fuel but there will be less air --> richer. I've been told that IATs over 90* can result in the PCM pulling 6* of timing. If things were tuned just right before, that should result in less of the charge being burnt --> richer. Both those effects would add to each other. Have you tried it at night? (disclaimer: all the above is wild speculation)
I agree that temp will affect A/F but would think it would be minimal.....If temp made a large difference then it would seem all cars (including stock)would have to be re-tuned from summer to winter?.........could it be that the dreaded adaptive nature of the PCM is changing things? My tune was done about 3 months ago and my WOT still runs about 11.8-12.0......same if the temp is 60 or 90.......I dont know how much adaptive poop the SRT10s have but I dont recall anyone complaining about it...may be different since the SRT10s have no ESP....
I was trying to remember if the effect of heat on density would be amplified at lower pressure (altitude). I forgot my physics but I'm thinking that might be the case. Let's a 30* increase in temp at sea level results in x% decrease in density, and a 30* increase in temp at 7000' results in a y% decrease in density. I believe that y is going to be larger than x. Maybe a lot? You know those gurus who sit on the top of mountains at the the top of the world and answer questions? It just occured to me that they're alway sitting on the ground. I've never seen one sitting in a car...
Good, quick article! This is exactly what I was thinking...but wow, so much? Got 7 days off starting Wednesday night so it looks like some post midnight blasts are in order. You know, if the WOT A/F ratio can vary this much...say below sea level at -20 degrees or whatever being the leanest, and 9000 feet at 100 degrees being the richest...manufacturers would have to tune everything for the worst case scenario, being the lean side. That leaves poor bastards like myself looking like a diesel unless you have the ability to individually adjust things with a tuner. Gay altitude. I ran across one of these gurus once on top of a mountain. I tried to steal his beer and he kicked my ass.
Larry, are there any adaptives for WOT? I have read both ways. I do know this: if I start raising the pedal slightly off of the floor and go almost WOT, I reach a definite point where closed loop kicks in and the car instantly starts controlling A/F ratio around 14.x.
If the short term adaptives are high enough they will eventually change the WOT tables. Now if what your seeing here is a culmination of that or a uncalibrated Lambda, that problem will be one you'll have to troubleshoot.
This is extremely interesting. I would imagine my adaptives have had to change quite a bit going from basically sea level to 7000 feet. If they do indeed AFFECT the WOT fuel value, this will be a somewhat difficult issue to track. According to my Predator, I have moved the bar to the lean side across the 3 RPM ranges 12% away from what my original CMR tune was at. If the adaptives are jacking with things also, I am going to have to adjust my WOT A/F ratio using only real time data (A/F gauge) and not pay as much attention to how far I have deviated from my original tune according to my slide bar on the Predator. Does this sound correct? Gay altitude.
My understanding is that there are no WOT adaptives per se. The PE table (WOT fuel) is for the amount of fuel added when in WOT mode. So the closed loop short term adaptives feed the closed loop long term adaptives. When you go WOT it uses the long term adaptive values and adds the amount of fuel specified in the PE table to that. So there are no WOT adaptives and the closed loop adaptives are not updated while in WOT mode, but they are factored in to determine the fuel. I think the fuel specified in the PE table is a fixed amount (not a percentage). That's why you had to adjust it when you got to the top of the world. Kind of like down at sea level you were adding 20 to 100 (where 100 got you 14.7). When you got up there you were adding 20 to 60 (where 60 got you 14.7). So you were way rich at WOT until you adjusted it. Blown-7 is the guy who'd know.
So in summary yes, the adaptives can change the WOT A/F?....assuming this, would just reflashing the tune take care of it...or does would it require changing the tables?....would removing the battery cable reset maybe?...
Or better yet, htf do I set things where I can keep WOT constant? I had things set right where I wanted them AFTER I got to "the top of the world" yet they have changed for the richer over, say, 400 miles... Maybe things are simply getting "set" for my area and will quit changing. Then again, maybe it is just too hot out. Or maybe I'll just change into a badger and dig a fucking hole right where I am standing. Hehe, gay altitude.
Your closed loop fuel adaptives adapt really fast. Like way inside of a minute? It doesn't have anything to do with "getting set". Something else changed and effected your WOT A/F. ....you know, there is always the possibility that your A/F didn't change but your A/F reading did... Does your gauge have a re-calibration routine you can do? Just a thought.
Ya, I thought about that too. If my gauge's probe were messed up I would think it would be across the board...ie.e my cruising A/F ratio would be affected one way or the other also...not necesarily true but that's what I would think. It is dead on where it was the moment I got in the car with the new motor.
