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Cobalt LSJ - boost limited to 3 psi - boost control solenoid - PID for monitoring
Hi all,
stock cobalt supercharged is supposed to boost up to 80 kpa (12 psi) stock, but for some reason my boost is limited to 20 kpa (3 psi) at WOT.
Whenever I bypass the wastegate solenoid, the car boost to 12 psi at WOT without any problems.
This leaves me wondering whether it's the ECM that does not command 100% duty cycle at WOT for some reason.
Commanding 100% duty cycle shuts off that valve (allowing full boost).
By bypassing it I disable ECM control over the supercharger (I get full boost in this case).
I would like to monitor my wastegate solenoid duty cycle.
I have a ODB reader and Torque app, that allows to enter custom sensor PIDs to monitor.
Let me know if anyone knows the correct PID to monitor wastegate solenoid duty cycle on Cobalt SS lsj (or even LNF, it could be the same).
My intercooler pump is working, so IAT2 temps shouldn't be the reason ECM would limit the boost.
I've recently started to monitor my air intake temp after the supercharger (IAT 2, sensor PID: 222006),
and after reading over 170-180F IAT2 I realized that my intercooler pump is not working.
We've replaced the pump (I can see the intercooler fluid burbling), and now IAT2 is at the levels of 140-150F.
DId some data-logging today, the IAT2 are within 115-140F (through 2nd gear WOT pulls). Given it's 86F ambient right now, these look way better that before changing the pump (it was 170-180F).
Forgot to mention that I've also changed the bypass solenoid itself - it's working correctly (checked that I cannot blow through it when 9V battery is attached).
Checked my bypass valve actuator today with simply blocking the nipples using a finger, both lower and upper nipple hold pressure.
I'm a bit at a lost on what else would be the reason to limit boost to 3 psi, other than bad ECU settings - the PCM was changed couple years ago, and it might be the case that this PCM has boost=disabled set, or whatever.
System has p0172 running rich code. That shouldn't command the ECU to limit boost afaik.
It also had p0033 before I changed the intercooler pump, now it's gone.
jdbaugh1, by physically disabling the boost control solenoid - by plugging the vacuum line that goes from boost control solenoid into boost valve actuator.
jdbaugh1, by physically disabling the boost control solenoid - by plugging the vacuum line that goes from boost control solenoid into boost valve actuator.
Check to see if your boost solenoid is getting power. It's normally energized to block the pressure from intake manifold and allow the line going to the bottom nipple of the actuator to vent freely to atmosphere. If it is getting power but not blocking the rear port, the solenoid itself is bad. If it's not getting power you either have a problem with the solenoid power circuit (not sure if there's a relay or directly powered from ECU) or your ECU is commanding bypass.
Check to see if your boost solenoid is getting power.
This is exactly what I'm trying to do right now - but can't figure out how to monitor it.
That solenoid is energized at full-throttle only, rest of the time it should have 0V sent to it.
Since energizing it (commanding a 90-100% duty cycle on it) only happens at wide-open throttle, I can't just use a multi-meter to measure the voltage.
For this reason, I'm looking for a way to monitor it by using an OBD2 reader and Torque Pro app, which allows to enter custom PIDs to monitor. I just need the correct PID to monitor wastegate solenoid duty cycle on Cobalt SS lsj (or even LNF, or in fact any GM vehicle).
For example here are all the Pids for Ford vehicles (don`t work with Chevy):
I assumed it was energized at all times besides when ECU is commanding bypass. Unless there is a check valve I don't know about it would have to be energized while the IM is in vacuum or it would be trying to close the bypass actuator. There very well could be, that I don't know about, as I don't actually have an LSJ Cobalt.
I assumed it was energized at all times besides when ECU is commanding bypass. Unless there is a check valve I don't know about it would have to be energized while the IM is in vacuum or it would be trying to close the bypass actuator. There very well could be, that I don't know about, as I don't actually have an LSJ Cobalt.
It should be 100% boost solenoid control the entire time, only reducing for reduced boost conditions.
Unfortunately idk which PID it is for Torque, just in HPTuners
This is for LNF, but the same concept applies to LSJ.
Here's a screenshot of HPTuners software adjusting the boost solenoid table. You can see that it's set to command 95% duty cycle to the boost control solenoid, when full boost is desired.
What that means is that boost solenoid gets 95-100% duty cycle (i.e. is fully energized) only at WOT, most of the time it stays NOT energized (0% duty cycle).
Energizing the solenoid closes it at WOT, which ensures full boost. Most of the time solenoid is not energized - i.e. it is open.
My main question is how do I monitor the duty cycle commanded to it by the PCM. We need to know the wastegate solenoid PID for that, or else use HPTuners MPVI2 software to monitor it (which is about 300$).
LNF and LSJ control boost very differently actually. Under normal conditions the bypass valve position is controlled passively by the vacuum created between the throttle body and the supercharger rotors. As far as I know the boost bypass solenoid isn't used to incrementally control boost pressure. The supercharger is fixed displacement with regard to rpm. The way I understood it on the LSJ, the bypass solenoid is basically an "on/off bypass operation.
LNF and LSJ control boost very differently actually. Under normal conditions the bypass valve position is controlled passively by the vacuum created between the throttle body and the supercharger rotors. As far as I know the boost bypass solenoid isn't used to incrementally control boost pressure. The supercharger is fixed displacement with regard to rpm. The way I understood it on the LSJ, the bypass solenoid is basically an "on/off bypass operation.
OP this. The LNF ECU is a torque based ECU not an airflow based ECU
I literally tune LNF and LSJ's trust me the LSJ shows 100% all of the time. The only time the bypass opens is when boost needs to drop, otherwise, it's always closed. The PID in Hptuners 100% is closed and 0% is wide open, I just did some idle logging for a local LSJ and the boost solenoid is 100% the entire time.
Here's a video that shows what the boost control solenoid duty cycle is commanded by PCM: https://www.youtube.com/watch?v=3qXtaTEhN7E This is for LNF, but the same concept applies to LSJ.
Here's a screenshot of HPTuners software adjusting the boost solenoid table. You can see that it's set to command 95% duty cycle to the boost control solenoid, when full boost is desired.
What that means is that boost solenoid gets 95-100% duty cycle (i.e. is fully energized) only at WOT, most of the time it stays NOT energized (0% duty cycle).
Energizing the solenoid closes it at WOT, which ensures full boost. Most of the time solenoid is not energized - i.e. it is open.
My main question is how do I monitor the duty cycle commanded to it by the PCM. We need to know the wastegate solenoid PID for that, or else use HPTuners MPVI2 software to monitor it (which is about 300$).
Also the LSJ does not have a wastegate, therefore those tables do not apply. The LSJ doesn't even have the PID boost control like a LNF does, boost is based off pulley size and airflow restriction on a supercharged car.
OP this. The LNF ECU is a torque based ECU not an airflow based ECU
I literally tune LNF and LSJ's trust me the LSJ shows 100% all of the time. The only time the bypass opens is when boost needs to drop, otherwise, it's always closed. The PID in Hptuners 100% is closed and 0% is wide open, I just did some idle logging for a local LSJ and the boost solenoid is 100% the entire time.
Thanks!
Yea that makes sense, solenoid energized (100% duty cycle) - the vacuum line is blocked, solenoid not energized - vacuum line is not blocked.
When vacuum line is not blocked (that goes into lower nipple of bypass actuator) - excess pressure in the intake manifold opens the bypass valve.
Thus to have full boost at WOT - solenoid needs to be energized (100% duty cycle).
Any way I can verify what's the voltage output on that solenoid without using HPTuners? I attached my multimeter with a 2 meter cord to it, the setup is pretty ghetto, but kinda works. The voltage shown is in milliVolts (only tried it at idle), which is way lower than it's supposed to be:
Boost Control Solenoid 2.0L LSJ supercharged engine only P0033
11 V < System Voltage < 18 V
People are able to close that solenoid with 9V batteries:
I figured out my issue regarding no voltage on the bypass solenoid. It turns out my PCM was swapped by the previous owner (by a repair shop, for unrelated reasons), and what was installed is a generic GM PCM, not the native LSJ PCM: "Refurbished module for ACDelco", part: 19209822. This PCM is marked as compatible with the following vehicles: Chevy Cobalt 2006-2007, Chevy Malibu 2006, Saturn Ion 2006-2007 https://www.carid.com/acdelco/gm-ori...-19209822.html When ACDelco marks it as "Refurbished", they remove previous part# stickers on it, thus it's impossible to know which vehicle it was taken from. I assume this PCM was originally installed on a Malibu, and it's software doesn't know to put any voltage on a bypass solenoid
Anyways, after installing a native LSJ PCM (part# 12597520, software: 12610623), it's 14V on that solenoid, and 12 PSI boost is back where it should be.
