My 302 runs better on hot days

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chad.lee@gmail.com - 04 Aug 2006 22:01 GMT

Hi all. I have noticed that my 84 Ford Thunderbird with 302 & EFI runs
better on hot days. On cool days it has normal acceleration but on
hot days, like today at 100 degrees F it has a lot more power. Why is
that? The engine and transmission are from an 85 30th anniversery
edition that i wrecked and transplanted, but the computer is is the
original 84. The original to my knowledge was identical, just worn
out. I had cleaned everything when I did the change over. Could it be
the plugs? Gas density? Fuel injectors? The EFI is the carb type
with two injectors. I put Berrymans in the fuel every few weeks or so.
I'm told that it should do this on cold days because the gas is
denser, not when it is expanded in the heat. How does one adjust the
mixtures on these without pying a new unused computer?

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DC - 06 Aug 2006 18:01 GMT

I take it your EFI setup is TBI. I have owned several TBI cars and the
following are some things to look at based upon what I have experienced.
First you may want to check to make sure your O2 sensor(s) are in good
working condition. It is possible you may be running too lean. Since in
warmer weather the air is less dense your air to fuel ratio would actually
drop to a slightly richer mixture. You may also want to take a look at your
TBI injectors and make sure you have a nice uniform spray coming out of each
of them.

What temp thermostat are you running? If you have a 160 degree you may want
to up it to a 185. I have seen many different engines actually make more
power around 180 as opposed to 160. In many cases I have actually seen the
computer on some cars go into limp-mode if a 160 degree thermostat was used.
In warmer weather the cooling of the engine would be less efficient and even
if you were running a 160 the engine may not actually cool any more that
170 - 175.

These are just some suggestions of things to look at. Good luck.

-DC

> Hi all. I have noticed that my 84 Ford Thunderbird with 302 & EFI runs
> better on hot days. On cool days it has normal acceleration but on
[quoted text clipped - 8 lines]
> denser, not when it is expanded in the heat. How does one adjust the
> mixtures on these without pying a new unused computer?

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chad.lee@gmail.com - 11 Aug 2006 18:01 GMT

Thanks DC.

Yes, it has the TBI. Central Fuel Injection on the 1985 cars, EFI on
the 1984 ones. Marketing?
I assume that my thermo is a 180 because it's normal running temp is
190. The oxygen sensor may have something to do with it. I did
replace it last year but I just noticed that the wire connector has
touched the exhasut and melted but I don't know if it was enough to do
damage. I might splice it together since it's melted anyway. I'll
also try to find a way and test it to make sure it works first. I
checked my injector spray buy using a timing light and that seemed to
show a steady spray. Maybe this will help someone else too.

Chad

> I take it your EFI setup is TBI. I have owned several TBI cars and the
> following are some things to look at based upon what I have experienced.
[quoted text clipped - 29 lines]
> > denser, not when it is expanded in the heat. How does one adjust the
> > mixtures on these without pying a new unused computer?

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