Seeing what you are talking about

[BHarvey]

According to the Ultragauge, my gph rate does indeed drop with higher intake temps. Goes from .2gph to .15 gph when the intake temps get to 130f+.

The question is how hot is too hot in intake temps and what are the issues involved?

[Daox]

Unfortunately, there is no way to know unless you do your own testing.

[cfg83]

BHarvey -

Listen to Daox. It's different strokes for different folks because the drivetrains respond differently. From what I have read about my Saturn S-Series, IAT above 180 degrees F will cause drivability problems.

For OBDII gauges that derive MPG from other parameters, I would make the claim that they are all using a form of the equation defined in this post :

http://ecomodder.com/forum/187883-post20.html

You will notice from reading the post that the IAT is part of the calculation when you need to create a pseudo-MAF (Mass AirFlow) sensor. Most cars have MAP (Manifold Absolute Pressure) sensors instead of MAF sensors.

CarloSW2

[euromodder]

Though it's on a diesel, my air intake temps go up to 50° C (122° F) when the diesel particulate filter is being burned free of soot.

[gtstanger01]

Bharvey do you have a hot air intake on your car or is the the stock intake?

[BHarvey]

The intake is stock which draws air from the upper part of the main grill, which is blocked off. There is a little sliver that it can draw air from. It mainly runs 40-50 over amibient on the highway. When in town it will run hotter, but mid 130's is the highest I've seen it.
As soon as it's crest's 125-130 the idle gph goes down .05

When testing out a mod for warm air, what danger signs do you look for, rough running, ignition being pulled, etc?

[Tygen1]

You should watch for the gph to rise, the instant mpg will fall or it will begin to misfire when you have exceeded the most effcient air temp. I've run mine up to 180 F and had no rough running problems, but the benefit dimished to the point that it wasn't worth it. Try some expiriments!