a/f question

06blackonblack · May 23rd, 2008, 09:30 AM

I have a question on the all important a/f to a FI car. When the temps outside go up ( in summer ) does this cause my a/f to get richer or leaner? I don't seem to know which it will be.

07stanggt · May 23rd, 2008, 09:54 AM

if it would do either it would be richer.

Trick Tuners · May 23rd, 2008, 01:33 PM

No, the AF should stay the same. The timing will compensate for different temps.

07stanggt · May 23rd, 2008, 01:39 PM

From the horses mouth.

I didnt think so but i guess the theory people have is richer right. cuaes of the hot air not being as dense. But i thought the pcm would compensate.

Trick Tuners · May 23rd, 2008, 01:42 PM

Originally Posted by 07stanggt

From the horses mouth. I didnt think so but i guess the theory people have is richer right. cuaes of the hot air not being as dense. But i thought the pcm would compensate.

The PCM does not have to compensate because our cars are MAF based (measure the actual mass of air, not the volume). If they were MAP based the pcm would need to compensate based on the IAT signal.

07stanggt · May 23rd, 2008, 01:51 PM

Originally Posted by Trick Tuners

The PCM does not have to compensate because our cars are MAF based (measure the actual mass of air, not the volume). If they were MAP based the pcm would need to compensate based on the IAT signal.

gotcha. so if its based on the mass of air and not the volume and hot air has less mass then cold how does it not affect it.

free education here

07stanggt · May 23rd, 2008, 01:55 PM

or i guess it will affect it from a performance standpoint but not an actuall a/f ratio is that what it is.

06blackonblack · May 24th, 2008, 12:37 AM

Thanks for the answer. It was a question no one could give me a straight answer on. My car was not extremely fat on the dyno so I was just making sure the warmer temps woudl make a differance. I guess I was wrong and it will stay the same. Good info and I will stop worrying now.

silvergtstang99 · May 24th, 2008, 12:42 AM

Originally Posted by Trick Tuners

The PCM does not have to compensate because our cars are MAF based (measure the actual mass of air, not the volume). If they were MAP based the pcm would need to compensate based on the IAT signal.

turbo cars are MAP based correct? So it would hinder them a bit?

May 23rd, 2008, 09:30 AM	#1
06blackonblack Newbie 2006 mustang gt vert 12.2@117 at 498 rwhp on stock tires Join Date: Feb 2008 Location: Cleveland Ohio Posts: 46	a/f question I have a question on the all important a/f to a FI car. When the temps outside go up ( in summer ) does this cause my a/f to get richer or leaner? I don't seem to know which it will be. __________________

May 23rd, 2008, 09:54 AM	#2
07stanggt Authorized Vendor 2007 GT 12.40@114.55 Join Date: Mar 2007 Location: Ellicott City, MD Posts: 6,627	if it would do either it would be richer. __________________ http://s275.photobucket.com/albums/j...ntyRaceway.flv www.radmustangs.com

May 23rd, 2008, 01:33 PM	#3
Trick Tuners Authorized Vendor KB'd GT Join Date: Nov 2006 Location: San Diego Posts: 1,124	No, the AF should stay the same. The timing will compensate for different temps. __________________ SCT Custom Tuning, JLT intakes, Aeroforce Interceptor OBDII gauges and PLX wideband products @ Trick Tuners email joe@tricktuners.com PM for super MM member deals! Super Cheap Motorsports Camera to record the Action!

May 23rd, 2008, 01:39 PM	#4
07stanggt Authorized Vendor 2007 GT 12.40@114.55 Join Date: Mar 2007 Location: Ellicott City, MD Posts: 6,627	From the horses mouth. I didnt think so but i guess the theory people have is richer right. cuaes of the hot air not being as dense. But i thought the pcm would compensate. __________________ http://s275.photobucket.com/albums/j...ntyRaceway.flv www.radmustangs.com

May 23rd, 2008, 01:55 PM	#7
07stanggt Authorized Vendor 2007 GT 12.40@114.55 Join Date: Mar 2007 Location: Ellicott City, MD Posts: 6,627	or i guess it will affect it from a performance standpoint but not an actuall a/f ratio is that what it is. __________________ http://s275.photobucket.com/albums/j...ntyRaceway.flv www.radmustangs.com

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May 24th, 2008, 12:37 AM	#8
06blackonblack Newbie 2006 mustang gt vert 12.2@117 at 498 rwhp on stock tires Join Date: Feb 2008 Location: Cleveland Ohio Posts: 46	Thanks for the answer. It was a question no one could give me a straight answer on. My car was not extremely fat on the dyno so I was just making sure the warmer temps woudl make a differance. I guess I was wrong and it will stay the same. Good info and I will stop worrying now. __________________

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