mrc_wkr
Probationary Member
- 10
- 2
- Jun 26, 2018
-
Columbia,
South_Carolina
I recently purchased a '94 talon tsi (FWD) - it has an aftermarket boost gauge mounted in one of the center vents. originally when i purchased the vehicle the boost gauge was reading mostly at the absolute negative pressure (vacuum) around -30. WOT would push it to a positive pressure but idle, and anything other than WOT would read -30. i looked under the hood to see where the boost line was connected - it is a manual boost gauge with the vacuum line running through the fire wall.
the FPS has been deleted off the vehicle as has the EGR(still in place but a block off plate is behind it with no lines running to it) as well as the PCV. so the intake manifold vacuum nipple towards the right side was connected to a T fitting where one side went to the boost gauge and the other to the fuel pressure regulator.
i removed the T fitting and ran directly from the intake manifold to the FPR and then ran the boost gauge vacuum line from the E port (the one to the left of port P). once i made this change the idle boost psi went to between -5 and 0, WOT showed approx 15psi, and a feathered throttle showed -16psi.
I would have used the P port but the blowoff valve is connected to that. using the diagram from the forum post below i searched for the intake manifold port to connect the blow off valve but couldnt find it (i am thinking it is on the bottom of the manifold and i just didnt see it)
https://www.dsmtuners.com/threads/taboo-speed-shop-vacuum-diagram-and-removal-for-1g-and-2g.198327/
so at this point i believe i have a possible vacuum leak that seems to be occurring mostly at idle (previous owner said wastegate is set up for 12-15 psi, there is no wastegate solenoid just the ball/spring). or the boost gauge is no good. it is a no name boost gauge and part of the casing is disfigured from being forced into the vent.
the only other thing i believe worth mentioning is the blow off valve flange has a poor weld on the intake pipe to the manifold, but i thought i would hear a constant boost leak from there if that was the source. for what its worth the other ports on the throttle body are plugged closed. thoughts?
on a side note, when i turn the key to on position the CEL never lights up. i assumed the bulb was pulled so i pulled the dash cluster and swapped it with the low coolant (parthenon/lincoln memorial) bulb as that one works. when i swapped the bulb the low coolant indicator lit up (meaning CEL bulb was good) but the CEL still did not. i am assuming with DSM link you can permanently turn off the CEL ? my car is running a downpipe only so i know they likely turned it off for lack of o2 sensors but i figured they may have left it functioning for other errors.
the FPS has been deleted off the vehicle as has the EGR(still in place but a block off plate is behind it with no lines running to it) as well as the PCV. so the intake manifold vacuum nipple towards the right side was connected to a T fitting where one side went to the boost gauge and the other to the fuel pressure regulator.
i removed the T fitting and ran directly from the intake manifold to the FPR and then ran the boost gauge vacuum line from the E port (the one to the left of port P). once i made this change the idle boost psi went to between -5 and 0, WOT showed approx 15psi, and a feathered throttle showed -16psi.
I would have used the P port but the blowoff valve is connected to that. using the diagram from the forum post below i searched for the intake manifold port to connect the blow off valve but couldnt find it (i am thinking it is on the bottom of the manifold and i just didnt see it)
https://www.dsmtuners.com/threads/taboo-speed-shop-vacuum-diagram-and-removal-for-1g-and-2g.198327/
so at this point i believe i have a possible vacuum leak that seems to be occurring mostly at idle (previous owner said wastegate is set up for 12-15 psi, there is no wastegate solenoid just the ball/spring). or the boost gauge is no good. it is a no name boost gauge and part of the casing is disfigured from being forced into the vent.
the only other thing i believe worth mentioning is the blow off valve flange has a poor weld on the intake pipe to the manifold, but i thought i would hear a constant boost leak from there if that was the source. for what its worth the other ports on the throttle body are plugged closed. thoughts?
on a side note, when i turn the key to on position the CEL never lights up. i assumed the bulb was pulled so i pulled the dash cluster and swapped it with the low coolant (parthenon/lincoln memorial) bulb as that one works. when i swapped the bulb the low coolant indicator lit up (meaning CEL bulb was good) but the CEL still did not. i am assuming with DSM link you can permanently turn off the CEL ? my car is running a downpipe only so i know they likely turned it off for lack of o2 sensors but i figured they may have left it functioning for other errors.