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Discussion Starter #1
I have 2000 e350 7.3 with 385,000 mi.,bought new. when temps get into 20's overnight ,i get a little hard start which is ok. but sometimes I get no power for up to 10 minutes. can only roll at 5 to 10 mph. is there a valve or something that could be sticking till warm. runs fine rest of time.Thanks for help.
 

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Exhaust back pressure valve. You can unplug it from the turbo and make it stop. Or you can completely delete it since it is known to leak oil.
 

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Wyso,

In addition to what KIB said.. look at the EBP sensor and tube to make sure it is reading the exhaust pressures correctly. FORScan (they have a number of recommended adapters) is a cheap tool that will pull live data from the engine PCM. I have read a post or two here that mention under powered performance when the sensor is not working correctly.

Cj
 

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Wyso,

There was another thread here somewhere in-which the OP had a malfunctioning Baro sensor that the internal gel had come apart and was pressing on (or blocking) the sensor. The incorrect readings were causing major engine problems.

Cj
 

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Discussion Starter #6
now the auto choke doesn't seem to be working when cold (40F). could that be related to EBP sensor?
 

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Wyso,

The EBP valve is not really a choke... not like a gas engine. It is more of a restrictor to keep the exhaust pressure up to help with warm up. Many 7.3 owners just delete the valve all together - usually when it starts leaking oil all over the engine valley. It is my understanding that the exhaust valve is not activated until it is colder that 38*F (give or take) by the temperature sensor that is located in the air filter box. The exhaust valve is not deactivated until the oil temp comes up to 170*F. Given that you are at 40*F you may or may not have the exhaust valve operating. I drive a 97 7.3 and from my observations on the exhaust valve:
moderate to heavy acceleration - no back pressure
slowing down/steady driving - back pressure around 15 psi
startup - initially no pressure, but system kicks in after a min or two of idling (I typically don't idle to warm up, as soon as the oil pressure comes up I get the truck moving, though I try to be easy on the revs and throttle till the engine has warmed up a bit).

As for diagnosing... the valve is actuated by the low pressure oil system. Look for oil around the base of the valve - leaks may cause the valve to malfunction. I have read once of a bad solenoid. I wouldn't panic too much about a non-functional back pressure system.

Cj
 

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Discussion Starter #9
so when I start the engine and it's cold and I let it idle, I assume that it's the PCM that raises the rpm's until the engine warms or I tap the brake. it hasn't been doing that on the last few mornings, (40F). I'm wondering why and if it could be a sensor. if so, would it be air, water, oil temp. or something else? thanks.
 

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Do you have any response from the accelerator? Mine would only idle below 20* till it warmed up. I traded positions of similar power relays in the fuse box and it has never came back. Maybe a connection or relay????
 
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