2.0L LSJ Performance Tech 205hp Supercharged SS tuner version. 200 lb-ft of torque.

Boost Issues

Old 01-22-2019, 07:26 PM
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Vex
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Boost Issues

New Cobalt owner. I have a 06 ss sc and the car is putting out about 2/3 lbs of boost. This car is factory, no mods. All vacuum lines have been replaced, bypass solenoid has been replaced, and bypass valve seems to be holding vacuum no problem.

Bypassing the solenoid produces full 11-12 lbs..

What am I missing guys any help would be greatly appreciated. Thanks in advance.
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Old 01-23-2019, 08:01 AM
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Check for power at your bypass solenoid. It must be energized to block intake manifold pressure from actuating the diaphragm which will open the internal butterfly bypass valve. As you say you have replaced the solenoid and when bypassed you produce full boost it is most likely the solenoid isn't getting powered up either from a faulty connection, fuse (if there is one for that), or your ECU is commanding it open for some reason. Is your check engine light on? I'm not sure what all conditions cause your ECU to command bypass mode but if you don't even have a check engine light I would think that wouldn't be happening.
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Old 01-23-2019, 12:30 PM
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Originally Posted by jdbaugh1 View Post
Check for power at your bypass solenoid. It must be energized to block intake manifold pressure from actuating the diaphragm which will open the internal butterfly bypass valve. As you say you have replaced the solenoid and when bypassed you produce full boost it is most likely the solenoid isn't getting powered up either from a faulty connection, fuse (if there is one for that), or your ECU is commanding it open for some reason. Is your check engine light on? I'm not sure what all conditions cause your ECU to command bypass mode but if you don't even have a check engine light I would think that wouldn't be happening.
so im getting the idea itís gotta be electrical. Iíll get it tested and check out everything electrical I can think of.

I do have a check engine light its for a thermostat, and fuel level sensor, circuit something or another. Didnít really look into it. I didnít think those would relate to the boost issues at all.
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Old 01-23-2019, 01:45 PM
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Just check for voltage getting to the solenoid. If it isn't powered up it's default position is "bypass mode". Inspect wires. I would think there would be a relay and fuse for the bypass solenoid but it could function straight through the ECU. I don't have an LSJ. I know how the solenoid works I just don't know how it ties in or communicates with the ECU.
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Old 01-24-2019, 06:20 PM
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inside the HPTuners program, there are options that limit boost output by temperature. i would assume that this would be a factor for safety of the overall engine - removing pressure will allow a huge margin of safety especially when engine's temp cannot be accounted for or misread. now that i think of it, if you have problems with fuel/coolant, boost will be minimized or not available due to those critical area's for this operation to occur. my 0.02$.
^^^^^^ - oops 2/3 of max - stock. not none at all. lol!

won't remove info above in case it's needed from another.

since you have repaired all the lines and nothing else has been done/running ok(?? i hope).
#1. check the Coolant reservoir in front of the engine's supercharger. (remove the cap and you should see water circulating with a slight Eddy-aka-Swirling vortex, on the bottom of the Neck, correct?) if not moving at all or barely sputtering, see below...
#2 check your Water pump in front of the engine on the bottom(Intercooler/Heat exchanger Pump) - should be bracketed to the engine, more towards the passenger side of the engine. check it if it is vibrating and functioning (review your mileage and if you are over 60k, replace the pump since it will go out sooner than "lifetime of the car". mine failed at 103k - seized then cleared and was running like a dog..old tired dog run** lol.

reason for these, the listed info above was partially correct towards your issue, just the fact that if you have High IAT(intake air temps) you will have a boost inhibitor that is in that same ballpark. but this has to be achieved prior to disallowing full boost. if you have tested with full throttlet on a mildly warmed up engine and compared the same for a fully warmed engine and had worse results with full warm, your Lamna-Intercooler might not have circulation and will remove %'s from overall boost allowances.
there could be other problems but for the basis of ECM - tuning, these are good pointers to get you going if you are in a rut. more info usually allows a more informed steps for you.

Last edited by cobaltss06sc; 01-24-2019 at 06:41 PM.
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Old 01-24-2019, 08:25 PM
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Originally Posted by cobaltss06sc View Post
inside the HPTuners program, there are options that limit boost output by temperature. i would assume that this would be a factor for safety of the overall engine - removing pressure will allow a huge margin of safety especially when engine's temp cannot be accounted for or misread. now that i think of it, if you have problems with fuel/coolant, boost will be minimized or not available due to those critical area's for this operation to occur. my 0.02$.
^^^^^^ - oops 2/3 of max - stock. not none at all. lol!

won't remove info above in case it's needed from another.

since you have repaired all the lines and nothing else has been done/running ok(?? i hope).
#1. check the Coolant reservoir in front of the engine's supercharger. (remove the cap and you should see water circulating with a slight Eddy-aka-Swirling vortex, on the bottom of the Neck, correct?) if not moving at all or barely sputtering, see below...
#2 check your Water pump in front of the engine on the bottom(Intercooler/Heat exchanger Pump) - should be bracketed to the engine, more towards the passenger side of the engine. check it if it is vibrating and functioning (review your mileage and if you are over 60k, replace the pump since it will go out sooner than "lifetime of the car". mine failed at 103k - seized then cleared and was running like a dog..old tired dog run** lol.

reason for these, the listed info above was partially correct towards your issue, just the fact that if you have High IAT(intake air temps) you will have a boost inhibitor that is in that same ballpark. but this has to be achieved prior to disallowing full boost. if you have tested with full throttlet on a mildly warmed up engine and compared the same for a fully warmed engine and had worse results with full warm, your Lamna-Intercooler might not have circulation and will remove %'s from overall boost allowances.
there could be other problems but for the basis of ECM - tuning, these are good pointers to get you going if you are in a rut. more info usually allows a more informed steps for you.
appreciate the input. Iím getting solid current to the solenoid. Coolant is good pretty sure the thermo is bad. I got after it the other day and didnít have the proper extensions to get into it so I figured I would give it another day. I should be able to crack into it tomorrow and replace the thermo. Water pump is good but I might go ahead a replace it anyways. Iíll keep ya updated
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Old 01-25-2019, 08:48 AM
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Originally Posted by Vex View Post


appreciate the input. Iím getting solid current to the solenoid. Coolant is good pretty sure the thermo is bad. I got after it the other day and didnít have the proper extensions to get into it so I figured I would give it another day. I should be able to crack into it tomorrow and replace the thermo. Water pump is good but I might go ahead a replace it anyways. Iíll keep ya updated
If the solenoid is getting current check and make sure the hose from the solenoid to the actuator is on the right side of the diaphragm. If it is then check to make sure the solenoid is oriented correctly. A boost line from the manifold should be routed in the back side. When the solenoid isn't receiving power it will route this boost pressure through the solenoid and to the line going to the actuator. When the solenoid is energized it will block the rear port completely off but will allow the front port to vent to atmosphere. You can test the solenoid by trying to blow through it when energized and de-energized. Test the front side as well to make sure it is venting to atmosphere when energized.
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Old 01-25-2019, 08:56 AM
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I don’t use a factory computer or electronic solinoid but the upper bushing on the butterfly valve needs to be lubricated very often or boost is reduced. A drop of oil directly off of the dipstick then right on the buterfly shaft bushing fixes it every time. I run in intense dirt, dust and heat is probably why but try that.
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