3.4l Install NotesDate: 2002, Jul 15
The last 2 weeks I have been installing a 3.4 in a Trooper.
Here are a few things that I ran into other than the normal "bolt up" activities.
If it is a auto trans with the eng. oil cooler there are 2 bolt
holes on the side of the block that have to be cut off
for clearance of one of the oil lines.
Here is the one I run into that gave me problems:
The troooper ran great but the idle was not to great.
After going back through every thing I found that if I
pinched off the fuel return line that the idle would
smooth out. I rechecked for fuel pressure, which was at spec for
13 psi, rechecked for vacuum leaks, none found.
After playing with it for a little bit I found that if the fuel pressure
was at 18 psi it found idle great.
Now, how do I get the fuel pressure up? I removed the fuel pressure
regulator on top of the throttle body and removed the diaphragm and found
an adjusting screw on the bottom side but no slot for a screw drive to turn
after doing some cutting a was able to adjust the screw and raise the
fuel pressure, but only to 15 psi. I still needed 3 more psi. Next I removed the long
spring that was a little weak and installed a brake shoe hold down spring out of a older
rodeo rear brake and adjusted it all the way up.
Then I had 22 psi of fuel pressure. Too much. After doing some more
adjusting i was able to get the fuel pressure to 18 psi.
Now this thing idles better then any 2.8 or 3.1 I have ever seen.
All it took was adjusting and removing the fuel pressure regulator about 30 times
This took about 3 hrs to do, first 1 1/2 was more trial and error.
If any body has done this swap and is having problems with idle then this may
be the fix for it.