turbo boost

April 28, 2011, 10:13:23 AM

for a 86 cougar xr7 2.3 5 speed vin w all stock. car runs great,engine runs smooth,sometimes when i push car on a high boost car backfires. any body can help me understand problem.turbo fine,spools

turbo boost

Reply #1 – April 28, 2011, 10:37:21 AM

What do you consider "high boost"?

turbo boost

Reply #2 – April 28, 2011, 11:23:35 AM

at 15 psi boost gauge

goes in red ,only sometimes

turbo boost

Reply #3 – April 28, 2011, 11:54:58 AM

Shouldn't be going that high of boost stock should it?

turbo boost

Reply #4 – April 28, 2011, 12:26:24 PM

Is this the same issue we addressed in this post?
http://www.foxtbirdcougarforums.com/showthread.php?31160-turbo-boost

First, you need to be much more descriptive in your posts. A "one liner" post is not going to help us help you solve your problem. Take the time to type out a detailed account of the problem.

Second, did you check the things we said to in the other post? A turbo system isn't rocket science, but you have to understand how the components work. If it is making more boost than it should the reason is because the wastegate isn't opening when it should. There could be a few reasons for this: The wastegate could be stuck closed. The wastegate is like a bypass for air that opens when the predetermined boost level is reached. If it is sticking closed, all the air keeps going through the turbine, which in turn continues to produce more boost. If you have access to an air compressor, about 10 psi to the vacuum line should open it. Do not overpressurize it as you may rupture the diaphragm.

Next, you could have a cracked vacuum line to the wastegate actuator. A cracked vacuum line is going to leak under boost and bleed off some of the pressure going to the actuator. The bigger the leak, the longer it will take the actuator to see the proper pressure to open the wastegate.

You may have a malfunctioning BCS (boost control solenoid.) This is the part that controls how much boost the actuator sees. It is a one of the lines from this goes to the actuator, so if it fails and doesn't open when it should, the actuator won't see the correct pressure and open. This part is EEC controlled and may not open if you have computer issues (bad grounds, etc.) If you run a line from the turbo outlet (pressurized side) directly to the wastegate actuator, it should open at 10 psi. This could tell you if the BCS is the culprit.