Hey guys so i just joined and I just picked up an 09 cobalt ss/tc used with just under 70k from a dealership but my only complaint is that the boost reading on the rpd just stays at 0psi no matter how I drive it. No CEL or codes. I haven't found any info on what it could be so any help is appreciated as I just got this car and am learning as I go. Thanks!

 

Did you bring that to the attention of the dealer before you drove it off the lot. I would highly recommend you reading up on the car as it will help to answer questions down the road. Does it boost in wide open throttle or not? Or does the rpd just not read it?

 

I'm going to guess you have a bad map sensor. Have a scanner pull the codes it should have one pending

 

I scanned the car with my scan tool and no pending or history codes. Ive taken it to WOT and the RPD boost display just stays at zero. I checked all the vacuum and boost hose connections but everything seems to be connected. You say a bad map sensor would do that but wouldn't that set the CEL with a code? Im really stumped. Thanks guys.

 

Can you monitor the map sensor with your scanner?

 

The scanner i have just checks codes for the car and the cars ABS. Should i take it to chevrolet? Bought it used from a ford dealer go figure. LOL xD

 

No, find someone around you who has HPtuners or buy a copy of HPTuners (you'll only need the standard) and have them scan the car while operating. I'm trying to recall when a local I tuned had a bad map sensor if it threw a code or not.

 

well it has 2 MAP sensors. one for the computer to read and the other for the RPD. Since theres no CEL its probably the MAP sensor for the RPD.

 

my question is which map sensor is used by the car for reference and which one does the RPD use for live boost data? Thanks

 

Eric when I lost the seal in my lower one it didn't throw a code even though boost was all messed up.

 

One isn't dedicated just for the RPD, the ecu uses both of them. The sensor in the intake manifold is what boost on the RPD references.

 

Ford dealer or not if you just bought it you should be able to take it back and have them fix it. At least where i live all cars used have at least 3 months of warranty. Unless its from a hole in the wall dealer that just sells used cars. I bought mine from a carmax and the mass air went out a few weeks after and they fixed it for free.

 

They said they couldn't do anything because they are ford. Typical right? Anyways about the RPD, it displays everything else except boost. Stays zero. What can I do other than take it back? What causes this?

 

Does it actually go into boost? Don't know if you have said that. Regardless of what the rpd says

 

Yes it goes into boost I can hear the turbo spool up and the car pulls very hard but boost on rpd still stays at zero

 

You may want to check both map sensors and the connections to them.

 

Where are they located?

 

One is right on the intake mani, the other is in the lower charge pipe just before the throttle body

 

I would also suggest you do a lot of reading on the car as it will help you to diagnose things that go wrong. Newer turbo cars can be a little complex with sensors and computer controls.

 

Understood. Thanks

 

Where's the wiring harness for the RPD located