I/P= Instrument Panel

 

Do this first before you chase your tail -

You need to read the codes, which most chain parts stores can take care of for you. Write down the numbers, not the descriptions. Also pester them to find your stored ethanol (or alcohol) %. They may have trouble finding that because it’s probably buried in a menu somewhere, so be politely persistent.

In the meantime, when the car is cold and doesn’t want to start, hold the pedal to the floor during the start sequence, which place is the car in “flood clearing mode.” If that helps, I’d like to know

in particular, I’d love to know if one of your trouble codes is P0172. You have a flex fuel car. GM has issued TSB’s about a relatively rare and apparently poorly understood problem in which the car gets confused about how much ethanol is in the tank. The result is hard starting and the problem often surfaces with the onset of cold weather. It’s pretty easy to fix.

Nothing wrong with cleaning the math sensor in the throttle body in the meantime. It may not help, but it won’t hurt. But please do make it a priority to get those codes checked.

 

I have not had a chance to do any work on the engine to correct the cold start issue. It is still starting hard but runs fine afterwards. Is is necessary to remove the throttle body to clean it?

 

BTW, I doubt that the fuel injector cleaner had anything to do with any improvement. The car may have started to correct itself.

Go back and read comment #12. All of it.

 

No. What I do is just have someone else (one of my younger brothers) come and sit in the driver's seat, key ON (but engine off), with their foot pushing the gas pedal all the way down - that opens the throttle body plate while I spray it with CRC throttle body cleaner and wipe it down with a lint-free rag. I've heard that it's risky to physically move the throttle plate with your fingers, so opening the plate electronically with the gas pedal seems safer

Then when I put everything back together and start it I just leave it idling in park for about ~5 minutes without touching the gas pedal at all so it relearns/adjusts it's idle speed now that the black carbon deposits have been wiped off. After the idle speed comes down to it's normal range then I just drive normally

 

I've done it both ways and yes, it's necessary to remove the throttle body to clean it right. Most of the carbon is on the inside of the butterfly where you can't get to it if it's attached.

Removing it from a non-turbo HHR is very easy and you'll do a much better job cleaning it with less fluid, and at the same time, avoid accumulating fluid in the intake and resulting smoke when you start it. Also, if you're really overdo it with the cleaning fluid, I suppose there's a risk of a hydrolock condition. That would be a disaster.

Without touching it, just spray both sides of the butterfly several times per the directions on the can of CRC throttle body cleaner.

 

I haven't held the pedal to the floor yet. I will do that. About two weeks ago the check engine light came on while driving on the highway. I got the codes which were P0445-0 and P0172-00. The light stayed on for the rest of the trip but the next day it was off and hasn't come back on yet.

 

The 2 codes are related. Too much air in the A/F ratio.

 

https://www.obd-codes.com/p0445

https://www.obd-codes.com/p0172


Replace the evap valve under the car by the driver’s side rear axle, make sure you reuse the oring seal as the new valve doesn’t come with one.

And clean your MAF sensor and throttle body!

 

Thanks for the info. I will get a new evap valve and clean the throttle body/MAF. As long as I use just a light coat of throttle body cleaner it shouldn't cause the hydrolock condition?

Today I held the pedal to the floor as mentioned and it started without hesitation.