Hey guys just thought i'd post up and ask if this is normal or not. When my car was tuned earlier this summer it was 80-85 out and fairly humid. Now last night here in WI it was about 58 out and no humidity. I got on it a little bit and noticed my afr was holding about 11.9 or so when normally on a 3rd gear pull it would be 11.6-11.8. Just wondering if this is because of the temp. I know 11.9 is still safe but i just noticed the difference. If anyone has any insight let me know. *** These readings are coming from a PlX-300 wideband about 2 feet away from turbo. I know the wideband is accurate.

 

IAT does affect fuel needs because air density changes with temperature. That's why there's IAT correction.

 

ok yea i figured....so do you think the iat correction is working properly? I know it's a little higher but nowhere near dangerous. Just wondering if the iat correction shouldn't allow the afr to change at all or if it can't be that accurate and allows it to fluctuate.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GSROWNSU &raquo;</TD></TR><TR><TD CLASS="quote">ok yea i figured....so do you think the iat correction is working properly? I know it's a little higher but nowhere near dangerous. Just wondering if the iat correction shouldn't allow the afr to change at all or if it can't be that accurate and allows it to fluctuate. </TD></TR></TABLE>

What are you tuned on.

Most systems the IAT compensation works pretty well but it's almost impossible to get numbers that will be perfect under any circumstances without realtime AFR feedback to the ECU (which, to my knowledge, is not currently available).

 

Someone correct me if im wrong here but, say he is down 20 degrees from what it was when it is tunned... now he is making a little more power hence the higher AFR's...you make more power on the same tune, you will run a bit leaner.

 

I agree with gringotegra. This sounds like it makes perfect sense with what is happening. Car is tuned on Hondata S200

 

Colder air=More denser air. Of course your gonna run more lean theres more air in the system. But either way it sounds like your safe, if your overly concerned the only way to get it right I think would be to tune it again...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TehGhett0P1mp &raquo;</TD></TR><TR><TD CLASS="quote">Colder air=More denser air. Of course your gonna run more lean theres more air in the system. But either way it sounds like your safe, if your overly concerned the only way to get it right I think would be to tune it again...</TD></TR></TABLE>
Or adjust the IAT correction...its easy on hondata s200

 

adjust your iat correction

 

last year i noticed about a .8afr difference between a 90 degree day and a 40 degree day on the same tune without real good iat corrections

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtecspeed1320 &raquo;</TD></TR><TR><TD CLASS="quote">
Or adjust the IAT correction...its easy on hondata s200</TD></TR></TABLE>

Is it something you can do easily even if you dont know how to tune..?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TehGhett0P1mp &raquo;</TD></TR><TR><TD CLASS="quote">

Is it something you can do easily even if you dont know how to tune..?</TD></TR></TABLE>
Yes as long as you know your way around the software. And you have a wideband.

 

I should be just fine. It's even colder out tonight and i got on it a little bit and at full boost i'm holding 11.8:1 I might have gotten a false reading the other night or even read it wrong. Thanks for all the help tho guys

 

Because I have no adjustable IAT correction, I tune for cold and go rich in the heat.

 

ok not sure if your AFR reads like my autometer wideband but saying 11.9 is leaner then 11.8 does not seem right. i looked at the paper work from my AFR and it stated that 11.9 would indacate a little fatter mix then your 11.8

 

11.9 is leaner than 11.8.

You just need to adjust the IAT correction, but I wouldn't worry about it too much. Even a brand new car's (let's say cobalt SS turbo) AFR's will vary slightly depending on temperature. 11.9 is still plenty safe.

 

but with iat correction, when its colder, the ecu will add more fuel or should

 

how do you guys tune the IAT Corrections? i am using crome pro.

 

crome and crome pro both have iat correction.

remember iat correction is a "margin of error" value to change the fuel values based on the intake temps so it will change slightly from the other factors that still play part in affecting the afr like humidity and the pressure outside. not sure if it affects timing at all or not but anyone want to elaborate?

 

With ectune there is IAT ignition correction.

 

thats sick. i like all the features of ectune. seems like an awesome program.