The fuel pressure has been tested, and that is good.

I will check the evap purge solenoid, if its that easy. I just need to look up a location for it.

There is a way to test the MAP too but I dont have a multimeter right now.

The temp is up, and the baro pressure is down around 29.7, and the starting thing persists. Expecting cold temps on Friday with the Baro remaining low, so hopefully that will show something as well.

Thanks for the input.

 

Under the hood driver side attached to the head. It's the thing with 2 black hoses and an electrical connector.

 

okay found it , and checked it.
Could not blow through it, so I guess that means it is fine.

on to the next ...

which is what?
the MAP?

 

The MAP is on the top of the intake manifold right next to the plastic tube from the evap solenoid. Don't know anything about testing it.

 

Here's another deal where a Tech II and an experienced tech would be a definite asset.

Most dealer techs have a "known good" sensor they use if a MAP sensor is suspect, checking for accuracy can be difficult as the readings will vary depending upon the current barometric pressure, and/or engine condition.

The other thing that can be done is to compare the "key on engine off" reading of your sensor to another like vehicle at the same time. Not practical unless you have another HHR kicking around.

Variations in barometric pressure will change the readings you get. Generally the Baro reading (key on engine off) will be around 4.6-4.8 volts.

At idle the MAP sensor will be in the 1.0-1.4 volt range, there are no hard set specs as such, just that the reference voltage can vary from 1-5 volts. When the voltage goes out of range it should store a code, but if it's intermittent, the code can self clear after a number of start cycles...and that number escapes me at the moment.

It might be time to enlist the services of your dealer's diagnostic technician, or find an independent tech who specializes in diagnostics.

 

You would be should get yourself an ELM327 OBDII reader and a good program on a laptop that is capable of live readings.

You can get a bluetooth ELM327 for $15-$20 on Ebay. And Scanmaster can be had for a reasonable price. The SmartPhone apps are not good enough. You are not going to be able to change anything past clearing codes since GM disabled that feature, but you will get most of the data that is available.

 

Well I have not been able to test the MAP, but the latest cold front allowed me to observe cold temps with higher pressure.
The temps got real cold, and the pressure over the last three days got up to 30.5 on average. And guess what, no starting problems whatsoever.
It has been starting perfectly.

Soo, I am leaning more towards tempurature dependent.

Yeah I wish I had access to one of those testers.

 

Kinda out of left field perhaps here - have you checked the air filter recently?

Can you think of anything that was done to the car a while back just before the issues started?

 

Hey whopper thanks,
I had checked the air filter in the past and it looked good.
I had also followed the advice here and tried to get the parts store to "pull" the codes and clear it. But their scans are simple. If no CEL then they can not read anything.

So what do you know, I finally got a CEL. I went to autozone and they told me po442, gas cap or small leak in EVAP.

I also had a headlamp go out so I had a fix it day. I changed the new locking gas cap back to the old OEM cap. I put in a new air filter, and replaced headlamps with silverstars.
Then this morning I took it to a dealer for oil change with proper weight oil. I also had them pull and clear the codes. (btw autozone will not clear codes)
Last oil change the dopes (at oil change place) put in 10W instead 5W. So we will see if perhaps that has any influence.

So far so good. No CEL light came back yet. Temps will be warm again this weekend so we will see if these actions change the symptoms any.

 

Alright, I have been waiting for it to get back over 70deg again.
Since the air filter change, and oil change, I have not noticed any improvements. As a matter of fact, I noticed a few non-starts happen at less than 70, which I never did before.

So air filter and oil change did not seem to have an affect. At least it did not fix the problem.

Actually, today I got another bleepin CEL.
A quick stop at Advanced Auto and they told me po128 - thermostat stuck open.
WTF!!
I just replaced the thermostat 2 months ago. I am beginning to hate this car.

Now I will go search on the forums for other reasons for po128...