Pick Up (Chevy and Ford)

MikeC

MikeC

Joined
Sep 16, 2005
Messages
1,364
Got a question for the metallurgist among us. I drive a Chevy PU now but drove 2 Fords before now. The fords would run better when it got cold say 40 degrees Fahrenheit and colder with the colder it got they better they both would run. The chevy is the opposite as it runs rough when it gets cold and better when its warm.

I'm assuming the Fords were machined to looser tolerances and that as the metal got cold and contracted the tolerances tightened up and performance improved. I'm also assuming the Chevy motor parts were machined to very tight tolerances so as it warms up and the motor gets a little looser it runs better. That is the only thing that makes logical sense to me, but I'm not a huge motor guy.

Anyone know for sure?
 
They're all tight tolerances now ,that's part of how they get the mileage,power and torque .The engines are changing all the time.There are many sensors and of course the software. All these things have an effect on how the engine works.
 
I suspect it has to do with the electronics, sensors, fuel pump and injectors... stuff like that.

I don't notice a difference between hot and cold in my '94 F150, but I did have an '83 Pontiac that would choke in hot weather and a '77 Buick that would barely run in the cold. Stupid carburetors.
 
All of these were recent models, say 95 through 02, and it is just weird because it happened in both Fords and now with the Chevy and expect everything is opposite. I just can't figure it out, no carbs, every one of them was fuel injected. Just wondering if someone had a legitimate explanation.

thanks
 
From my days on the farms:

The Fords always ran and rarely made us walk.
The Chevy's ran better when new but, didn't hold up as well over time.
 
The only thing I can think of is that Ford uses a pretty light-weight oil from the factory in the interest of improving fuel economy. That might thicken up to a more "normal" weight in the cold. I'm not sure if Chevy does the same. Fords are also OHC and Chevy PUs are OHV, but I doubt that would make any difference.
 
I'll buy the whole electronics argument maybe it has something to do with the high humidity we have here, yesterday it was 100 degrees and over 90% humidity it was hot. We have been home since 5 pm it is now 8, we turned the ac down from 80 to 76 when we got it and it hasn't stopped running yet.

Thanks for the replies and good to hear from powernoodle I haven't ran across you in a while, since you posted that picture of your suburban and some leftist told you "that you didn't need that big truck". Remember that?
 
Burke said:
The only thing I can think of is that Ford uses a pretty light-weight oil from the factory in the interest of improving fuel economy. That might thicken up to a more "normal" weight in the cold. I'm not sure if Chevy does the same. Fords are also OHC and Chevy PUs are OHV, but I doubt that would make any difference.
Click to expand...

:thumbup: That's what I was thinking too.
 
Burke said:
The only thing I can think of is that Ford uses a pretty light-weight oil from the factory in the interest of improving fuel economy. That might thicken up to a more "normal" weight in the cold. I'm not sure if Chevy does the same. Fords are also OHC and Chevy PUs are OHV, but I doubt that would make any difference.
Click to expand...

The main reason that Ford uses thinner oil is because they are OHC engines, not because of mileage, at least is what was told to us at automotive technology school.

The cams need lots of oil, and it is easier to push thinner oil up to the top of the engine. I have seen what happens when stubborn people run 15w40 in Triton motors, and it gets really expensive, really quickly.

The Ford Triton motors take 5w20, and I believe that the newer GM Vortecs take 5w30, so they should be similar in viscosity at operating temperatures anyway, but the Ford oil will be a little thinner when cold.

In cold ambient temps, the oil shouldnt be a lot different in temperature than in warm temps, as the operating temps of the engine are still the same. Obviously in extreme temperatures difference will be slightly greater.




To the OP..
It is probably a function of the ECU programming, and not of the tolerances of the respective engines. It should be noted, however, that internal combustion engines tend to run better in cool weather, due to the increased density of the air.
 
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