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2008 Pontiac Solstice GXP - Mysterious (with unkown origin blue sparkle in rear bumper cover paint)
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Finally got everything squared away. Turned out to be a combination of carbon and the ecm. I had the gm intake and valve induction service done first. He said my pistons and most likely rings were pretty built up with carbon. The chemical is poured into the cylinders and left for a few hours. Normal build up the outcome is a tea colored liquid. Mine was closer to dark coffee. I also saw the residue on my intake manifold where it all wasn’t cleaned off. Then they run the chemical through the throttle body and let it heat soak for another hour or so. I noticed a difference from this when driving home. Much smoother acceleration and it does seem to pull harder and smoother idling without the burping that I had regularly. The crc I used a few times helped but it came back shortly.

After this was done he hooked up his scanner and test drove. Still getting all cylinder misfires but no noticeable misfires. All cylinders misfiring at the same time most of the time too. He did an injector test where he briefly shut off each injector and obviously felt that when performed on each injector. Injectors checked out fine. Next item to look at was the ecm. He replaced the ecm and did whatever programming was involved with that and voila no more misfires on the test drive. First time he’s ever had an ecm reading misfires that weren’t actually occurring. He’s been doing this since ‘77 and he’s had plenty of carbon issues especially with the 3.6 gm but has never had an ecm be the issue.

I had a nice talk with him before I left and found out gas plays a huge roll in the carbon issue and as luck would have it Florida has some of the worse gas in the country. GM actually sent an engineer here because the 3.6’s were getting warranty work on carbon issues as early as 5-6,000 miles. They called in a fuel engineer who tests fuel and what they found out was the fuel was considered well below what many other states are getting quality wise. He didn’t know the details of the fuel and what made it not so great. Also, on the carbon cleaners, gm’s cleaner is about the best you can get snd he’s tried just about all of them professional and over the counter. It’s better than BG, amsoil, etc,,, it’s not as great as what they once used but that cleaner was banned from use as it was considered very toxic. Catch cans can help some but won’t eliminate carbon buildup. There is zero chances of preventing carbon buildup on these motors other than having them cleaned every 10k or so. I was curious about how many times he’s performed this and he said a ton. The 3.6’s get so bad that he pulls the intake and actually floods the heads with the cleaner and uses zip ties to scrape off the carbon sometimes. Walnut blasting and dry ice is also great for removal he said but messy can be messy with the walnuts.
BTW, be glad you don’t have to deal with love bugs. 40 minute drive and I just washed her last night🤦‍♂️🤦‍♂️
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Am curious, is the GM cleaning performed for you available to end users or only direct through GM dealerships?
 

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2008 Pontiac Solstice GXP - Mysterious (with unkown origin blue sparkle in rear bumper cover paint)
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Also... DAMN on the bug-capolypse! That is some heavy buggage brother.
 

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Discussion Starter · #83 ·
Am curious, is the GM cleaning performed for you available to end users or only direct through GM dealerships?
You can buy the in tank cleaner. He said that is very good at keeping the tank and the lines clean along with the tops of the pistons. We know it won’t do anything for the valves. Do not over use it. He said once every six months or so down here, better quality gas areas once a year is plenty unless you are driving a lot of miles.
I didn’t ask about the cleaner he used in the cylinders or the intake. He said it comes in a bottle or jug I believe but we’d have to find a way to atomize it unless you wanted to close the valves and pour it in the head. I’m going to stop in there next week or so. Was so happy it was fixed I forgot to grab the tank cleaner and some gm power steering fluid before I left.
Love bugs are bad twice a year here. Very acidic and even protected paint they say no more than 24 hours or it’ll start etching the clear coat. There are times I’ve washed both front ends every day for a week.
 

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Discussion Starter · #84 ·
The gasoline will impact carbon buildup inside of the cylinders. Where the GXP is prone to having carbon buildup is on the backs of the valves. since the GXP is direct injected and not port injected the gasoline never touches the backs of the valves. On port injection the gasoline acts like a solvent and cleans off the backs of the valves, this doesn't happen with direct injection because the gasoline is shot directly into the cylinders.

You should have him read the write up I did on the PCV design problems, carbon buildup on the valves, oil in the intake tract and in the CAC (intecooler) and how to solve the problem without having to have the valve cover modified.

I can dig that up for you if you want. I would be interested in knowing what he says after reading it. There was another GM master tech that has read it and agreed with the diagnosis and the solution.
I forgot to add he did mention the pcv system in these motors was not well designed. I mentioned the check valve on the intake to the plastic nipple and he started to laugh. He said more like valve with no check. He said like we’ve read on here to clean it often but it still won’t stop oil vapors from passing through and into the turbo. He also said the ripples in the intake tube definitely help slow it down and allow it to puddle in those valleys before getting to the turbo and a modified intake that is smooth actually makes it worse allowing the oil straight to the turbo as the air isn’t disturbed as much. The actual pcv valve is under the intake and a pain to get to but should be cleaned as well.

He’s a cool old dude. I told him about our forum and he can always tell when people come in who either work on cars or belong to these. Very good information that average Joe doesn’t know and it’s very good if you have a newer tech. If anyone else on here needs any work done to come on in and request him. I will pass on the information on the write up you did. He seems like he’s be interested in it.
 

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@R&T

Thanks. I will PM you a link to the write up on it. I have to go looking for it. I am not talking about the brief explanation I gave you. I did one that was a lot more detailed in what is happening.
 
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'07 Base - Lil' Red Devil and ‘07 GXP - unnamed
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Also... DAMN on the bug-capolypse! That is some heavy buggage brother.
Had the same issue on the roads from Buford, SC to Charleston....Riding my motorcycle back to the Navy base after seeing a girl in Buford. Had so many bug wings flapping on my face shield that I had to stop 5 times on a 90 minute ride...those things smear horribly when you try to clean them off.
 

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Discussion Starter · #87 ·
Had the same issue on the roads from Buford, SC to Charleston....Riding my motorcycle back to the Navy base after seeing a girl in Buford. Had so many bug wings flapping on my face shield that I had to stop 5 times on a 90 minute ride...those things smear horribly when you try to clean them off.
Yes sir. Wipers only make it worse and if you don’t have a strong sealant on your paint the guts can start etching your clear coat in day or two. Don’t even let them get baked on there by the sun. There are times I have to wash the front of our cars every evening for days at a time. My 2000 psi washer couldn’t even remove all of the residue on my windshield that had been baked on there.
 
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