why is there a diff between being cold and warm?
- Thread starter 97powerstroker
- Start date
Sawboy
Full Access Member
32 is cold??? You SURE you're from Michigan? 
JMF350
SDD Junior Member
Your problem lies in the turbo pedistal. It has a oil pressure operated valve that closes the warm up valve in the exhaust exit of the turbo. The spring that is overcome by oil pressure get weak, thus taking longer to open the valve back up (the oil has to warm up and thin out for the spring to push back out). It's a common thing with the 97 and olders. That's a design change they made for the 99 and newers.... the went to a vaccum operated set-up.
97powerstroker
Full Access Member
so the newer sd's can be started up cold,and be driven like they were warm,there performance isnt any difference,cold or warm,is that what your saying.
JMF350
SDD Junior Member
With my 99, as long as it's above 10-15*, I can start it and hammer down.... but I don't. They shop I work for has a 97 rollback, if it's below 40-45*, it'll take 2-3 miles before it has enough heat in it to open up.... and that's with it plugged in at 30*.
Nope, no vaccum set up on the 99+.Still an oil actuated piston that closes the EBPV on the turbine outlet.
95_stroker
Jefe
This part is partially correct. The EBPV is oil operated but it may not be his problem.
The rest of this is completely false. Espescially the last statement.
(1)im just curious to why my truck is much slower and sluggish when its cold.
(2)i have to give it more gas when i let the clutch out,it doesnt accelerate nearly as quick and also sounds different.
(3)everything works the same whether it be cold or warm,so why the difference in performance? somebody take me to school real quick.thanks
Back to the beginning ?
1. The BASIC operateing principle of any Diesel engine is HEAT. Without HEAT ? Poor Performance.
A. An Ambient Air Sensor in or near the filter box, an Oil temp sensor and a Coolant temp sensor on the engine tell the PCM the engine is Below normal operating temperature.
B. PCM signals the Glow Plugs to cycle, providing the initial heat required to start a combustion process, due to the lack of Heat.
C. PCM closes the EBPV, restricting exhaust flow, raises idle RPMs and makes some fuel flow adjustments.. ALL, to speed up the warm-up. (The AIH has a role too, if needed in very low idle temps)
2. While A thru C is in action, our engines will be sluggish and have what seems to be.. Low Power. The Fan clutch is also engaged, adding to the different sound.
3. Until the PCM receives "All Systems & Temps are Go For Launch" signals from ALL the sensors mentioned above.. our PSDs run Poorly.
All Simply Put.
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strokin'_tatsch
death row inmate #7
97powerstroker, your truck runs better after the engine is warm in cold weather because the turbo is putting colder air into your engine. the cooler the air charge means the denser the air charge making your engine run better and more efficiently. does your truck run bad just when it's below 2000 rpm's like mine or is it at all rpm's when it's cold? if it's just running bad at below 2000 rpm's then it can't be because of the EBPV because it still restricts exhaust making it run poorly at all rpm's. right?
97powerstroker
Full Access Member
my truck is slow all the time,but when its cold its just more sluggish,it never runs bad,its just slow.when its cold it sluggish all around the rpm band.ive got a banks exhaust brake also.
