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Discussion Starter #1
Hi there.

I'm back to the forum after a prolonged absence and may have missed some of the juicy discussions about this topic, so forgive me if I'm beating a dead horse. I'd just like some advice... A couple years ago, the check engine light came on in my 2007 GXP (45k miles). My local dealer reported the code as a cylinder 2 misfire. They swapped plugs and reset the OBD system. A couple weeks later, the light came on again. This time, I had my independent mechanic plug in the reader... Got the same code. I had him swap coils. A couple weeks later, same code. I went to another dealership (the owner actually raced Solstices) and his mechanics recommended a top engine solvent flush, suggesting that there was carbon buildup around the valve(s). I did it. All was well for about 200 miles and then the light came on again. Yesterday, I went back to the same dealership (which now is under new ownership) and they recommended replacing all of the injectors! That's a $2500 service on a car worth $8500. I've never noticed any issues with performance during the life of the car, so I'd love to just put a piece of electrical tape over the warning light and ignore it... Unfortunately, in my state, you can't get an inspection tag with an active code coming up.

Is it possible and/or difficult to swap injectors. Any other words of wisdom?

Thanks!
 

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I think I would try a couple bottles of injector cleaner first like Techtron (I've used this stuff for a lot of years with great success )unless you run some real bad gas or your car sits for long periods of time without a fuel stabilizer Sta Bil you should not be experiencing this type of problem . I'd drop in a bottle then fill up with fresh good grade gas run it out and repeat .What codes are you throwing ? If you don't have a code reader to clear the code just remove the negative battery cable ,let it sit for a couple of minutes reattach and the code should be cleared . Replacing injectors is not difficult do a You Tube search to get an idea it does not have to be model specific and remember to disconnect power to the battery before you start .
 

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First we need the code. Next....I disagree a bit with Sting Ya. I believe the Techron ruined my HPFP. Nothing is EVER going to touch your intake valves and in the DI motor, nothing is ever going to clog your injectors. Not at 1200psi. Don't let a dealer tell you they can clean your intake valves. You have to have them walnut blasted. Injectors can go bad. Someone here had 2 bad ones IMSMC and he showed the spray. Usually if you are having the same misfire code, from what I've learned here, it's usually a blown head. If it's (IMSMC) the number 1 cylinder as it runs the hottest.
 

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Discussion Starter #4
Thanks for the comments... The code has consistently been a misfire on cylinder 2. I neglected to mention that the dealer did a leak down compression test and everything was normal. I'll also note again that engine performance appears to be completely unaffected.

Interesting to hear about your experience, The_Ghost. I was about to try the injection cleaner option...
 

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I would swap coil packs and see if it continues complaining about cylinder #2
 

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$2500 for injectors? You're freaking kidding me, right?

I realize the GXP DI injectors are expensive, but they're also not insanely difficult to replace. I'd suggest shopping around.

Also, it's pretty easy to test an injector. Have they done that, or are they just randomly replacing parts in the hope that it'll fix the problem? The easiest thing to do here would be to swap the coil and injector from the errant cylinder to another cylinder, and see if the misfire code follows it. Also, check the wiring harness connectors for the coils and injectors and make sure there isn't a broken wire. (It happens, surprisingly frequently.)
 

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Discussion Starter #7
I've already swapped plugs and coils. The cylinder 2 misfire code persists.

Tell me about it!!! $2500... Good grief. The car's only worth $8500. They did not test the injector. How do you do that? They did do a leak down test and found that there were no compression issues. Next I'm gonna swap the injector out and see what happens. I'll also check the wiring.

Thanks for the help. :)
 

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There a few ways (Google it), ranging from listening with a stethoscope (or length of rubber hose, or a long metal rod pressed against the injector), to removing the injector and seeing if it's firing (ie, spraying gas when it's supposed to), and others. It really comes down to comparing the operation of the potentially-bad injector to a known-good injector. If you have the proper equipment, you could also bench test it with a waveform generator and an oscilloscope.

Either way, if you swap only the injector to another cylinder, and the misfire moves to the new cylinder, it's a pretty safe bet that the injector is bad. Same goes for coils, etc. One injector cost between $200 and $400, as far as I can tell, and shouldn't be that difficult to replace. Takes about 20 minutes on the LE5, but the LNF is a bit more involved since the injectors go into the top of the head rather than above the intake manifold.

Save yourself $2000 and move the injector to another cylinder, replace it if the misfire code follows it.
 

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Discussion Starter #9
I concur. Interestingly, my wrench is friends with a GM master tech who works on a lot of the local late model Corvette club cars. He recommended a round fuel system cleaner first. We're gonna try it. I'll report back with our findings.

Thanks!
 

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Discussion Starter #10
Update!

Hi gang!

UPDATE! It's been over a year now and I'm still having absolutely no performance issues of any kind, but the misfire code has persisted sporadically and I've gotten not only cylinder 2 codes, but more recently, also cylinder 1. Coincidentally (or not), beginning a year or so ago, the safety switch on the clutch that allows the starter to crank began to malfunction intermittently. First, every 20-30 cranks, then increasing in frequency over the past year until I was getting one or two cranks every 20 or so starts. Obviously, I took it in and had that switch replaced (under $50), which solved the starting issues. At my last visit, my wrench suggested that perhaps the misfire issue was related to the repeated unsuccessful crank attempts due to the faulty clutch switch... Sometimes the switch would allow a partial crank and then cut off the power to the starter.

Since my clutch switch replacement, the check engine light went off by itself and hasn't returned... Hmmmm. I reset the OBD and will let you know if anything new happens.

FYI, my Sly 2007 GXP has 55k on the clock and I'm the original owner.
 

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That's very interesting.....so this was some time ago...what's the latest?

I have a no symptom misfire on # 1 which I have cured with a first a coil connector. Light came back on several months later and Lucas cleaner turned itself off. Came back on several months later and is still bugging me. It's no the plug; I changed that out. Will try the coil next but that could be new (if the dealer rally did replace it when I bought the car)
 

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Swap the coil from #1 to another cylinder. Swap the plug to another one, and the injector to a third.
 

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Like john said, do some swapping. Put the #1 plug in the #2 cyl. and the #1 coil in #3 cyl. If the code switches to to #2 or #3 you will know if it was coil or the plug. If you still get the code in the #1 position, try unplugging and replugging the injector electrical connector. If that doesn't work, try another injector. I would save the injector swap for last. that aint an easy job like the coil or plug.
 

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Discussion Starter #14
Hey, kentlarue. Last summer was when I had the clutch switch replaced. No codes since then... I'm in New England, so I only drive my Solstice in the warmer months. I've put a few hundred miles on since the repair, but all is well so far. : )
 

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Discussion Starter #15
Not sure if you read the entire thread, but a couple of years ago, I did do a top end solvent flush (as recommended by the dealer to solve the misfires) which, in theory, dissolves carbon build up around the intake valves caused by the GDI/PCV issues... The owner of the dealership raced Solstices, so the guys working on my car were actually Solstice experts. Despite having a couple of codes immediately after the treatment, I feel like that may have alleviated the problem, since the clutch switch started acting up just afterwards and that may have caused similar issues.

Bottom line, if you're experiencing the same carbon build-up issue, might be worth a flush.
 

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Not sure if you read the entire thread, but a couple of years ago, I did do a top end solvent flush (as recommended by the dealer to solve the misfires) which, in theory, dissolves carbon build up around the intake valves caused by the GDI/PCV issues... ........
Do you have any details on this flush? I did a quick search and found oil and coolant flushing but nothing that would affect the intake valves. I will search a bit deeper, but if you have information it would save me some effort.
 

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For your information

I finally traced my p0301 misfire to a bad coil pack. I did a bunch of other stuff first to no effect. This was a bit of a red herring since the dealer told me he'd replaced that coil and plug in June 2019. CEL was on at the dealer and he performed some work and cleared it. When it came back on I discovered a frayed coil connector and that cured things for several months. It came back on and a couple of cans of Lucas injector cleaner seemed to cure it for a while. When it came on yet again I replaced #1 plug with an ACDelco and also fixed the crankcase breather tube connection as per a forum suggestion. No change. Finally I bought a ACDelco coil on ebay (turned out to be a Denso in Delco clothing/box - not sure what's up with that) and put it in in one minute flat - easier than changing your wiper blades.

Cleared code and it hasn't come back after several drives and cold starts so I'd say with confidence that it's gone. Reader says "no codes" words I love to read.

Hope this is of some use to those of you with a p0301 mystery.
 

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Glad you got it fixed.

I came across some information that doesn't apply to this specific problem, but would apply to a P0302, P0303, P0304, or possibly anything else that is cylinder specific for other than the #1 cylinder.

GM posted this footnote with a set of diagnostic information:

Capture.PNG


Diagnostic data normally refers to the cylinder number, but for the LNF it appears that it applies to the firing order number.
 

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Discussion Starter #19
Do you have any details on this flush? I did a quick search and found oil and coolant flushing but nothing that would affect the intake valves. I will search a bit deeper, but if you have information it would save me some effort.
It's been a while since you posted this. Sorry for the delay in responding...

The owner of my local dealer races his own Solstices in regional stock car events. A couple of his track wrenches work in the service department. When they saw the misfire code, they immediately recommended the top engine solvent treatment. I'm not sure exactly how it's done, but they told me that they introduce a solvent liquid directly to the valves and let it sit for a couple of hours and then flush. Following this service, my codes went away for a year. A few weeks ago, the check engine came on again. I don't have a reader, but I'm guessing it's the misfire again... I plan to take my car in for a brake fluid flush early next season. I'll have them read the code and let me know and I'll keep you posted.
 

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It's been a while since you posted this. Sorry for the delay in responding...

The owner of my local dealer races his own Solstices in regional stock car events. A couple of his track wrenches work in the service department. When they saw the misfire code, they immediately recommended the top engine solvent treatment. I'm not sure exactly how it's done, but they told me that they introduce a solvent liquid directly to the valves and let it sit for a couple of hours and then flush. Following this service, my codes went away for a year. A few weeks ago, the check engine came on again. I don't have a reader, but I'm guessing it's the misfire again... I plan to take my car in for a brake fluid flush early next season. I'll have them read the code and let me know and I'll keep you posted.
I'm confused. You said your p0301 went away for a year, but this thread is only 3 months old. Did I miss something? Would that be why I was called Rip Vanwinkle today? ;)
 
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