Hello All,

I have a 2007 Chevy Cobalt and I am having some issues.

My intercooler pump is not working, I've just replaced it with a brand new pump, refilled all of the coolant and I am still getting nothing. I've checked the fuse which was good and the relay is good, as well.

I'm kind of at a stand still here. Maybe one of you could point me in the right direction. Also, the car seems to be limited to 3 psi of boost. I've changed the bypass solenoid and have done the bypass mod (as a temporary measure; after I saw it didn't work I reverted it back) and still am not getting the proper boost.

The car is stock no mods or tunes.

Thanks.

 

Check to see if there is voltage at the IC pump electrical connector. I had an issue with mine in the past, I had to bend the pins slightly so they'd make contact. You could also check the circuit for continuity at each terminal on the connector using a multimeter, this would help rule out corrosion or breaks in the wire.

 

Thanks for the reply. I've checked for voltage at the connector; there was none. I also checked for voltage at the fuse socket; there was none there either.

But today, I was driving and my RPM gauge went to zero and my coolant temp went to 79 and, the car stalled. The thing would not start for 5 minutes; I finally got it start, and raced the thing home. That's an issue for another thread, though. Sorry for the short rant; i'm just starting to wonder if this is all connected.

Any other ideas for the intercooler pump connection issue?

 

How would I do this?

 

You will have to set your meter to the continuity setting and ensure the probes are plugged into the correct positions. When the probes are touched together the meter will make a beeping sound and/or display a resistance value. You will then use the IC pump circuit to bridge the connection between the probes, take one probe of the multimeter and connect it to one leg of the IC pump connector, either positive or ground. Then take the other probe and connect it to either a good ground spot or the output pin for the IC pump relay (whichever corresponds to the pin tested at the IC pump connector). The car doesn't need to run as the multimeter is providing the voltage for the test, if you hear a beep the connection is good and if there is a large number displayed and very little to no beep, chances are there is corrosion or a potential break. Here is a video showing the basics .

 

Did you buy an OEM pump or an aftermarket one on e-bay?

I remember when mine broke I tried using some CX Racing POS from e-bay and the thing never worked.

 

Yes, I bought a OEM Bosch pump. The thing was a real SOB to change!

 

Thank you! I will test this out today and let you know what the results are.

Do you think it is a PCM going bad, or is it hard to say?

 

I tested the plug end last night. The results I got were no continuity to negative OR positive.

I ordered a new plug from ZZP because the old plug was in bad shape, and the pins were all bent. I will wait until that comes in and install it and test it. I will then update this thread with further information once that is done.

Thank you guys for all your help so far. But I have a strange feeling this is not the end.

 

The way your car is acting at the very least you have some fairly serious electrical issues and the pump not working is just one of the symptoms. I'm assuming your check engine light is on. Have you had the codes pulled and could you tell us what they are? When did the low boost or other issues start happening and was it after any particular event or work that was done to the car?

 

Thanks for the reply.

No, the check engine light was not on, which to me was weird. The code reader would not link up to the to ODB-2; I was getting a link error message. I inherited this car from my brother, so the boost issue could have been an issue all along. No specific work or event brought this on.

But, I have found the issue; that will be in a separate post. I just wanted to answer your questions directly.

Stand by for the update.

 

Correction: OBD-2 not "ODB-2." Sorry.

 

Good News, I found the root of my problems, well, all accept one. The boost is still a problem.

After doing some digging, I found that a ground was extremely corroded and hanging on by a strand. I was having issues with the car not starting, AT ALL no crank, no nothing; I did not post that specific issue because I was disgusted with the car at that point. This all started after doing some troubleshooting with the pump; I was yanking on the harnesses and must have disturbed an already crappy connection. So, the next day, after some sleep and deep thinking about the issue, I found it.

When I touched the wire I heard a click, and I just had a feeling that this was the cause of my issues. So, I took the connection apart, re-crimped the bad connection and cleaned the intact connections, put it all back together, and boom she fired right up. And the pump is now working with no issues.

Side note: The wire was attached to the engine block and it was one big connection, and another small connection under it.

I took the car to work today with no issues, no codes, live data from my reader looked good.

The boost is still an issue, though. I've changed the boost bypass solenoid, changed some hoses that were dry rotted, and lubed up the bypass actuator. Any other ideas? I had a thought that maybe I could use my code reader to see what kind of live data I could pull off the MAP sensor, just to rule out my boost gauge being bad. Does this make any sense?

Thank you.

 

Oh, I also put a new battery in the car since the other one was very old. I read that a bad battery can cause those funky symptoms.

 

Sorry for the mountains of text, guys. This is my first time owning a car like this and I'm excited to get it running properly!

Thank you to everyone who has helped, so far!

 

Send us some pictures on the hose routing to your boost bypass actuator. Also, check that you can move the boost butterfly on the supercharger by hand.


This is how the bypass mechanism should look when the car isn't running or is making boost. The valve is normally closed so if it was stuck open all the time the rod coming out of the actuator would be sucked in.

 

PIC 1

PIC 2

PIC 3

PIC 4. Here I am pointing to the vacuum line that goes from the back of the boost bypass solenoid to a port off the intake manifold. It's basically a extension of PIC 3.

I can actuate the boost bypass valve with my fingers, so it's not ceased.

 

Is this how you performed the solenoid bypass test?

 

I will give this a shot today and let you guys know.

My weekend is going to be busy so the post about my results my be delayed.

 

I tried the this out; there was no change. The bypass solenoid is brand new, that was one of the first things that I changed.

I also installed a new boost gauge. No change.

Any other things I can do?
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You could have somebody rev the engine with completely to the floor skinny pedal blips and watch the actuator to make sure it is closing. If it is closing all the way I only see three possibilities for that low of boost, horrible belt slip, completely shot supercharger snout coupler or rotors, or huge boost/vacuum leak. If that valve closes the supercharger has no choice but to pump air if the rotors are spinning. Do you see any black dust buildup around the supercharger pulley or does it make any noise?

 

No black dust build-up, no weird noises, the supercharger does whine; but I think that's what a supercharger normally sounds like. Would the black dust be indicative of belt slippage?

What are good places to check for boost/vacuum leaks?

Should I just change the bypass valve? That's one thing I never changed. I DID change the bypass solenoid.

Thank you.

 

Does the supercharger whine all the time? Excessive black dust can be an indication of belt slippage just like burning a tire when it slips it wears off the belt surface.

Now that I think of it the bypass valve/actuator are normally closed. So if you just had someone start the vehicle you should be able to watch the valve go from closed, with the engine off, to open when it starts building vacuum on the back side of TB. I wouldn't replace it if it is working. The only way it could be causing your low boost issue was if it got stuck open somehow which you would be able to see when the engine is off.

 

The supercharger doesn't whine all the time; only when I really step on it. It almost sounds like it should be boosting, but it's not.

The bypass valve is working; I tested that.

Where should I start looking for vacuum leaks? What else should I be looking for?

 

I can't remember if we've covered this yet and too lazy to go back and read through but do you have any fault codes set? From what I've seen the LSJ formulates it's boost reading from the reading on the MAP sensor. Your MAP sensor could be faulty and reading wrong. As far as that goes your gauge could be faulty as well. How does it feel when you accelerate? If your supercharger actually was only making 3 psi the car should accelerate like an absolute turd.

For you to have that large of vacuum leak I'd think you'd have a high idle rpm and if you looked at the fuel trims with an OBDII reader it should have high fuel trims at idle as well. You could connect the hose that runs to the back side of your bypass solenoid (this line taps directly into intake manifold) directly into a cheap boost gauge to verify the manifold pressure.