STRANGE OR NOT STRANGE PSD
Elder User
Joined: Aug 2002
Posts: 656
Likes: 0
From: South of you
STRANGE OR NOT STRANGE PSD
The other day I took my neighbor for a ride to show him the gains using the Superchip Micro Tuner...bought from Motorhaven BTW... I guess the truck had sat for about an hour. I started it and idled for a couple of minutes. When I stepped down on it, it ran OK, but seemed to lack the get up and go I am used to. After we drove about a half mile, it was fine. I have read this before, but what will make the PSD seem sluggish when cold? The outside temp was in the low 70's. Any ideas on this? I am baffled.....even more than usual.
Senior User
Joined: Dec 2001
Posts: 304
Likes: 0
From: san diego usa
STRANGE OR NOT STRANGE PSD
Hey ceejay,
Just some guesses...
Could be that it was just cold, if the block is cool then cylinder temps drop and you have less power.
The turbo shaft spins on a film of oil, if the oil is cool then it doesn't spin as well. While working on my turbo, I've spun the impeller by hand both warm (not hot) and cold, and it definitely spins easier when warm, probably spins effortlessly when hot.
The fuel gets recirculated and heated, so after a bit of driving the entire tank gets warmed up and the fuel going to the injectors is warm (plus the whole engine heats up, making the fuel rails toasty), which makes it flow better... probably provides a better spray pattern, maybe other things.
Mine doesn't have a ton of power when cold either... haha I live in Southern California, I guess 65 degrees isn't really COLD.
Just some guesses...
Could be that it was just cold, if the block is cool then cylinder temps drop and you have less power.
The turbo shaft spins on a film of oil, if the oil is cool then it doesn't spin as well. While working on my turbo, I've spun the impeller by hand both warm (not hot) and cold, and it definitely spins easier when warm, probably spins effortlessly when hot.
The fuel gets recirculated and heated, so after a bit of driving the entire tank gets warmed up and the fuel going to the injectors is warm (plus the whole engine heats up, making the fuel rails toasty), which makes it flow better... probably provides a better spray pattern, maybe other things.
Mine doesn't have a ton of power when cold either... haha I live in Southern California, I guess 65 degrees isn't really COLD.
Posting Guru
Joined: Feb 2001
Posts: 1,465
Likes: 2
From: Indianapolis
STRANGE OR NOT STRANGE PSD
Exhaust gas backpressure regulator (EBPR) in the turbo (looks like a big butterfly valve) closes when cold to aid in bringing up the coolant temp to get your heater going.
Elder User
Joined: Aug 2002
Posts: 656
Likes: 0
From: South of you
STRANGE OR NOT STRANGE PSD
Thanks, LW555....and The Diesel Dude (haven't heard from you in a while, Joe....have you been on vacation again?). Both your answers summed up what I was guessing. The thing runs just fine after about 5 minutes, just like it always did. I guess we have just been having cold weather (45-70* here in south Florida) so it was a little colder than usual....poor thing has not even been through a real Florida winter yet....can't wait for those frigid 35* mornings at the beach...although it goes right back to the mid 70's by 10:00 A.M. so I can't complain that much. 
