What is this sound? (Start up choke) - Page 3 - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

My Caroline · 08-06-2014, 02:51 PM

Bump.

My Caroline · 08-09-2014, 07:41 AM

Car goes in Thursday. I'll keep you posted.

Towlie · 08-09-2014, 08:01 AM

i have a SS and when i bought it in florida they had crappy 87 in it. every time i started it hot/warm it would give a knock on start up like that. I changed gas to 93 after that tank was gone and reset the fuel tables and....presto, start up knock gone!

PQ · 08-10-2014, 01:02 AM

Quote:

Originally Posted by Towlie

i have a SS and when i bought it in florida they had crappy 87 in it. every time i started it hot/warm it would give a knock on start up like that. I changed gas to 93 after that tank was gone and reset the fuel tables and....presto, start up knock gone!

Interesting.

My Caroline · 08-26-2014, 06:00 PM

Well y'all, she's back.

And I have an answer.

As it turns out, the choke on the start up was caused by "excessive carbon build up" on the throttle body. The tech took apart, cleaned, reassembled and relearned the idle. THIS LAST STEP IS IMPORTANT. Over time the carbon on the throttle body caused the throttle to relearn a new position.

NOW, normally I would say this all sounds like bull.... But it worked.
And its only crazy if it doesn't work.

I have been driving the car for a week now just to be sure before I posted, and so far, i have not had one start up issue.

On to the cause of the build up...
bad gas quality.

Now, due to no fault of mine, all the gas where i was out at school was crap gas. I had no choices.
Now that I have transferred schools, I am able to get the good stuff.

Good Luck to anybody else experiencing the issue. Maybe you can tell your dealer where to start.

RobertRS · 08-26-2014, 07:18 PM

I'm wondering how low grade gas would cake up a throttle body on a direct injected engine? Maybe the poor fuel quality caused the rings to gum up which led to excessive blow by and hence ended up on the throttle body. Maybe a good cylinder decarb would be in order as a follow up to the throttle body cleaning.

My Caroline · 08-26-2014, 08:48 PM

Not sure, but everything is going smoothly. It used to do that every, single, time

I would imagine it has something to do with the "catch can" territory.

PQ · 08-26-2014, 10:47 PM

Cool to know what the issue was.

I was going to say the same thing as RobertRS. Gas should not ever get on the TB. The port injection is too far downstream.

Catch can vapor is PCV so it wouldn't get on the TB either.

It's the 'clean' side crank case venting vapor getting on it. Along with anything that bypasses your air filter. You'll have to just clean the TB every year or so or, correct, buy a clean side catch can.

TommyTheCat · 08-27-2014, 04:24 PM

It is not because of bad gas quality, it is because you need a catch can. These 3.6L engines have excessive blow-by

See here
http://www.camaro5.com/forums/showthread.php?t=374218

08-06-2014, 02:51 PM	#29
My Caroline Drives: Black 2011 Camaro LS Join Date: Feb 2011 Location: Texas Posts: 1,694	Bump. __________________ White Fender Hashes from Big Worm Graphix with Custom White Bowties GM Factory Remote Start and Factory Key Fob SS Fascia, Factory RS HIDs, Plasma P13W fog lights Non-RS to RS and fog light harness by Gen5DIY LED Interior, Trunk, and Licence Plate lights in white ZL1 Spoiler with Gen5DIY harness Factory NPP cat back Blacked out tail light bezels Factory 20 inch wheels wrapped in Nitto Motivos Lowered 1.25inch on Eibach Pro springs

08-09-2014, 07:41 AM	#30
My Caroline Drives: Black 2011 Camaro LS Join Date: Feb 2011 Location: Texas Posts: 1,694	Car goes in Thursday. I'll keep you posted. __________________ White Fender Hashes from Big Worm Graphix with Custom White Bowties GM Factory Remote Start and Factory Key Fob SS Fascia, Factory RS HIDs, Plasma P13W fog lights Non-RS to RS and fog light harness by Gen5DIY LED Interior, Trunk, and Licence Plate lights in white ZL1 Spoiler with Gen5DIY harness Factory NPP cat back Blacked out tail light bezels Factory 20 inch wheels wrapped in Nitto Motivos Lowered 1.25inch on Eibach Pro springs

08-26-2014, 06:00 PM	#33
My Caroline Drives: Black 2011 Camaro LS Join Date: Feb 2011 Location: Texas Posts: 1,694	Well y'all, she's back. And I have an answer. As it turns out, the choke on the start up was caused by "excessive carbon build up" on the throttle body. The tech took apart, cleaned, reassembled and relearned the idle. THIS LAST STEP IS IMPORTANT. Over time the carbon on the throttle body caused the throttle to relearn a new position. NOW, normally I would say this all sounds like bull.... But it worked. And its only crazy if it doesn't work. I have been driving the car for a week now just to be sure before I posted, and so far, i have not had one start up issue. On to the cause of the build up... bad gas quality. Now, due to no fault of mine, all the gas where i was out at school was crap gas. I had no choices. Now that I have transferred schools, I am able to get the good stuff. Good Luck to anybody else experiencing the issue. Maybe you can tell your dealer where to start. __________________ White Fender Hashes from Big Worm Graphix with Custom White Bowties GM Factory Remote Start and Factory Key Fob SS Fascia, Factory RS HIDs, Plasma P13W fog lights Non-RS to RS and fog light harness by Gen5DIY LED Interior, Trunk, and Licence Plate lights in white ZL1 Spoiler with Gen5DIY harness Factory NPP cat back Blacked out tail light bezels Factory 20 inch wheels wrapped in Nitto Motivos Lowered 1.25inch on Eibach Pro springs

08-26-2014, 08:48 PM	#35
My Caroline Drives: Black 2011 Camaro LS Join Date: Feb 2011 Location: Texas Posts: 1,694	Not sure, but everything is going smoothly. It used to do that every, single, time I would imagine it has something to do with the "catch can" territory. __________________ White Fender Hashes from Big Worm Graphix with Custom White Bowties GM Factory Remote Start and Factory Key Fob SS Fascia, Factory RS HIDs, Plasma P13W fog lights Non-RS to RS and fog light harness by Gen5DIY LED Interior, Trunk, and Licence Plate lights in white ZL1 Spoiler with Gen5DIY harness Factory NPP cat back Blacked out tail light bezels Factory 20 inch wheels wrapped in Nitto Motivos Lowered 1.25inch on Eibach Pro springs

08-26-2014, 10:47 PM	#36
PQ Booooosted. Drives: 2010 Supercharged SS Join Date: Apr 2008 Location: Mobile, AL Posts: 36,716 View My Garage	Cool to know what the issue was. I was going to say the same thing as RobertRS. Gas should not ever get on the TB. The port injection is too far downstream. Catch can vapor is PCV so it wouldn't get on the TB either. It's the 'clean' side crank case venting vapor getting on it. Along with anything that bypasses your air filter. You'll have to just clean the TB every year or so or, correct, buy a clean side catch can. __________________

08-09-2014, 08:01 AM	#31
Towlie Drives: 2013 2SS/RS L99 Join Date: Jul 2013 Location: Austin, Texas Posts: 142	i have a SS and when i bought it in florida they had crappy 87 in it. every time i started it hot/warm it would give a knock on start up like that. I changed gas to 93 after that tank was gone and reset the fuel tables and....presto, start up knock gone!

08-26-2014, 07:18 PM	#34
RobertRS Drives: 2014 2SS L99 Join Date: Mar 2014 Location: Corpus Christi Texas Posts: 1,320	I'm wondering how low grade gas would cake up a throttle body on a direct injected engine? Maybe the poor fuel quality caused the rings to gum up which led to excessive blow by and hence ended up on the throttle body. Maybe a good cylinder decarb would be in order as a follow up to the throttle body cleaning.

08-27-2014, 04:24 PM	#37
TommyTheCat SHKE BKE Drives: 2013 Camaro Join Date: May 2014 Location: SoCal Posts: 3,108	It is not because of bad gas quality, it is because you need a catch can. These 3.6L engines have excessive blow-by See here http://www.camaro5.com/forums/showthread.php?t=374218