why is there a diff between being cold and warm?

[95_stroker]

Your truck being sluggish when cold is completely normal, you've got front and rear differentials full of stiff grease, you've got a cold tranny, cold crankcase oil, cold axles and wheel bearings. All that cold oil and iron make for a lot of resistance to roll in addition to a diesel compression combustion engine that is not 100% efficient when not up to operating temps.

Its got nothing to do with charge air temp, its got nothing to do with your pedestal or any other thing internal to the engine except cold stiff fluids.

 

[97powerstroker]

Your truck being sluggish when cold is completely normal, you've got front and rear differentials full of stiff grease, you've got a cold tranny, cold crankcase oil, cold axles and wheel bearings. All that cold oil and iron make for a lot of resistance to roll in addition to a diesel compression combustion engine that is not 100% efficient when not up to operating temps.

Its got nothing to do with charge air temp, its got nothing to do with your pedestal or any other thing internal to the engine except cold stiff fluids.

END OF THREAD, THANKS

 

[rickh]

You guys missed that part about "Sounds Different".
Have you disconnected or removed the Exhaust Back Pressure Valve yet?
It will close off the exh during warm up and make the engine sound different and cause poor performance.
Rick H...

 

[johndeerebones]

You guys missed that part about "Sounds Different".
Have you disconnected or removed the Exhaust Back Pressure Valve yet?
It will close off the exh during warm up and make the engine sound different and cause poor performance.
Rick H...

What Rick said, but you do have a straight pipe, so I'll make it simple. If your truck sounds like a jet engine when its not running good, your ebpv is stuck, otherwise everything else.

My truck shows what you talk about though. We both have 97 f250 with 5 speeds, what is your pcm code? Mine is MLE 1. If yours is too here is how it should act, err how mine acts anyway.....


EXTREMELY long glow plug on times, I mean if it below 50 degrees they are on anywhere from 1 minute to 2 minutes in the mornings. Atleast 30 seconds to 1 minute even in the summer time mornings.

Idles higher and seems to have advanced timing when cold (less than ~50*)
Runs sluggish first 2 or 3 miles, but runs great after that. Especially when cold out. Like strokin tatsch (sp?) said, above ~2000 rpms, runs fine cold. Colder air has more O2 in it, so ANY turbo charged engine will run better with cold air, provided the engine is warm.

Once warmed up the glow plugs rarely come on at all unless it sits and cools down...

What 95 stroker said about cold fluid is true, but the effects will be minimal with the exception of an automatic transmission needs fluid, so could be a difference, AND when the engine is cold ALL electronic transmissions change their logic to help warmup times and deal with cold oil.

I venture to say that the effect might be 8 10 rear wheel hp difference cold diffs etc to warm, but not much more. Probably similar to the difference of switching from dino lubes to synthetic lubes. The difference is there, but only racers are concerned with spending several hundred dollars on syn fluids to gain a couple horsepower, guys go syn for the protection of their parts.

 

[97powerstroker]

well,to be honest,i dont know my pcm code,but my glow plugs have never stayed on for more then 15 seconds,even when it got to 32 degrees out.

 

[95_stroker]

The glow plug cycle lasts longer than the WTS light stays on.

 

[97powerstroker]

The glow plug cycle lasts longer than the WTS light stays on.

i was just talkin about the light,it never stays on for more then 15 sec.

 

[95_stroker]

i was just talkin about the light,it never stays on for more then 15 sec.

Your plugs are active longer than the light indicates.

 

[97powerstroker]

i want to tow something,anybody have anything i can tow,broken down chevys,dodges,toyotas,nissans,anything?:

 

[johndeerebones]

i want to tow something,anybody have anything i can tow,broken down chevys,dodges,toyotas,nissans,anything?:

ROFL Like he said though, WTS light is nothing to do with gp on time. Just a calculated guess by the pcm of when it should start, not always right, esp for us guys that see cold weather.

To add something to my last post though, I said the only major benefactor of cold oil was the auto trannies, I lied, err didn't think my statement through. In a perfect world, 15-40 diesel engine oil would be pretty fluid at freezing temps, but pour it out at 25* and at 90* and you can visually see quite a bit of difference, so in our engines that also adds to the effect, as our injectors rely completely on engine oil to fire.