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Discussion Starter · #1 ·
First off, my car had 50,000 miles on it. Its an 08 GT

Back in March, I was driving down the highway (400 miles away from home) and the car completely shut down and went into limp mode. I was able to get it to a dealer and they said the MAF went bad. I was charged $160 in parts and $160 in labor (yes its BS just to undo 2 screws but I had no tools and was in a hurry). They assured me the problem was fixed and I went on my way thinking I was good.

Fast forward to a few days later on my trip home. The car did the same exact thing and I was able to make it to another dealership. They said it was my injectors that were clogged and needed to be clean. I knew that this was a TSB so I went ahead and spent another $170 on that. Then they assured me that it was fixed.... It wasnt. This visit was on a Tuesday. To top it off, 10 miles down the road I got a flat. NEVER USE THE POS THAT THEY CONSIDER A SPARE REPLACEMENT. Not only did it ruin the TPS Sensor, it ruined the tire so that it could not be patched, only replaced (the shop was closing and didnt have time to clean and dry the tire)

Now 4 days later I took the car out because I had a feeling it wasnt fixed. And I was right. The problem only happens on long drives over 100 miles. Of course when it happened the dealership I normally go to was closed. They checked it out the next morning and kept it for a few days. They put over 250 miles on the car and said that they could not recreate the problem. They gave me all the codes it threw from the history in Miami and Melbourne (im in Jacksonville) and said that they did not want to work on the car and not know the proper fix which I admire that. They said that cylinders were running lean, rich and misfiring but they had no idea what was causing it. Another $120 down the drain.

Now a month later, the car is still running rough, mpgs are down by about 3 and I have not had a chance to put another constant 150 mile drive to check it out. I was running 87 the entire time (my dad took it to Orlando using 93 and didnt have an issue). I notified GM Customer Service and they concluded that "the issues are all separate and I would not be getting a refund. If I wanted to further investigate the issue, he would gladly set up an appointment with a dealership to get the car fully checked out... on my dime with a slight chance it would get refunded" the representative had no knowledge on cars whatsoever (didnt know what a MAF was or did). Also they closed my claim for now since it seems my car is working perfectly fine... They basically said my car fixed itself.

So basically Ive spent over $600, still have a broken car that was never fixed and cannot trust my car to drive clients (and that was my main reason of getting this over a Corvette)

:soapbox: done
 

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How about a new ECM, or at least reprogramming the current one? It might have a screwy brain...

But, I definitely feel your frustration. It might be worth selling it.
 

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I hate to say it, but the saying "If you want something done right..." comes to mind. I would get a scan tool and keep it in the car. It really comes down to trading that bad boy in or reproducing and diagnosing the problem yourself, unfortunately.
 

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Discussion Starter · #4 ·
How about a new ECM, or at least reprogramming the current one? It might have a screwy brain...

But, I definitely feel your frustration. It might be worth selling it.
I honestly think it is the ECM. The dealerships cannot prove that it is or isnt. Ill post the codes when I get home on my computer since I have compiled a list of the codes and what causes them (and none point to the MAF or Injectors)

I hate to say it, but the saying "If you want something done right..." comes to mind. I would get a scan tool and keep it in the car. It really comes down to trading that bad boy in or reproducing and diagnosing the problem yourself, unfortunately.
Ive reproduced it but it only reproduces when the dealership is closed. I only want to take it to the dealer since I still have the powertrain warranty until October. The second dealership that did the injectors said that the next thing would be a top end tear down for a vacuum leak. Ill post up the videos that I got when it did act up (transmission acted up also)

and to top it off, I started the car this morning and thought I heard the dreaded lifter tick :(. I love this car to death and I found an 09 with 77k miles for 18.5 but it didnt have a sunroof
 

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Discussion Starter · #5 ·
Here was one issue (the transmission related one)

and here is a knock that popped up when the car loses power

P0151-Oxygen O2 Sensor Circuit Low Voltage (Bank 2, Sensor 1)
Causes: Faulty o2 oxygen sensor ‘
Short to voltage on O2 signal circuit
High resistance or open on O2 signal circuit

P0131- Oxygen O2 Sensor Circuit Low Voltage (Bank 1, Sensor 1)
Causes: Faulty o2 oxygen sensor ‘
Short to voltage on O2 signal circuit
High resistance or open on O2 signal circuit

P0300- Random Misfire
Causes: Faulty spark plugs or wires Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector(s)
Burned exhaust valve
Faulty catalytic converter(s)
Stuck/blocked EGR valve / passages
Faulty camshaft position sensor
Defective computer

P0174- System too Lean (Bank 2)
Causes: The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
There could be a vacuum leak downstream of the MAF sensor.

P0171- System too Lean (Bank 2)
Causes: The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
There could be a vacuum leak downstream of the MAF sensor.

P0102- MAF Circuit Low Input
The MAF may be disconnected, or a wiring connection may be bad
The MAF may be dirty or otherwise contaminated (Note: if you use a reusable oiled air filter, be careful not to apply too much oil or that can contaminate the MAF).
The MAF sensor may be faulty
The vehicle computer may be faulty (very rare)



All of those popped up multiple times (not just at the first dealership where they replaced the MAF)
 

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Whoa... that's a lot wrong ^_^.

Did both banks show the O2 sensor failures at the same time? Is your EGR okay?
 

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Discussion Starter · #7 ·
I believe so. I first got it scanned at an Advance auto parts and it said that the o2s were shot. I bought 2 of them but the shop I went to was closed so I went to the 1st dealer. When they deleted and recreated they said they got different outcomes. Plus if the o2s were bad, I would assume they would be bad 24/7 and make the car run the same.

And Im pretty sure my EGR is ok. On my T/a the EGR was deleted and it didnt cause any issues
 

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Discussion Starter · #9 ·
Nope the only thing done to the car is a rear muffler delete.
 

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I hate to say it but I'd get it to pass muster and sell it. That's just one of those demon cars

I mean unless its possessed I can't think of any other reason why it'd torture you :-/

Edit: sounds more complicated than this but take the time and check your grounds. A lot of gremlins hang out around those ground cables and connections.
 

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I know your car is red but it is starting to look yellow and smell a bit citrusy...
 

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Well, if you didn't have the low voltage to your O2 sensors, I would have said intake manifold/vacuum leak. I'm gonna say ECU, Ground, or Fuse.

Look through all your vacuum cables and make sure there are no marks on them or holes. That they are sealed correctly. Specifically the one that goes to your intake. As your car heats up, it could cause a hole to open wide causes *some* of the issues you're seeing.
 

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You may have given up by now. But if not (I hope), There is a relay in the underhood fuse box R13 labeled *PWR TRN*. At ignition on, it energizes and powers up 5 fuses near by. Those fuses power up *all* your coils, injectors, Ho2 sensors, evap purge valve, all DOD lifter solenoids as well as ignition power into the ECM.
If the contacts within that relay are badly pitted (not unlike distributor points of old), maybe the voltage thru them degrades to a point (at times) and effectively starts shutting down the ability of all of those devices to a point of running ratty, or outright shutdown.
It looks like relays R9 and R10 are the same P/N (by looks in the service manual). They control wiper blade speed low an high. You could reverse R13 with either of those, and do some trial tests to see if there is any or complete correction to this nightmare of yours.
PS--To avoid a total meltdown, maybe do this somewhat close to your house. This relay stuff, at least is a no cost check/test.
 

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That sucks dude , sorry to hear. If shes been nothing but trouble for a long time.,sell it but if its just been these past few months ,I'd say try and fix her . If she no fix ,then obviously sell.
 

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sorry to hear about your dilemma. Belive it or not, i had a similar problem with my car after it sat for a month without driving it. The battery is original and it was causing the car to stall (when under alot of load going slow around 90 degree turns lol... For the live of me i couldn't figure it out? Slowing for a light it would surge and not want to kickdown to 1st on its own, almost stalling then as well. Sounds to me like you have a loose or beat up ground somewhere, bad cell in your battery causing an intermittent short, or as others suggested a corrupt file, or bad ecm.. So many possibilities, you might want to really consider trading it in.. best of luck, keep us posted.
 

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Seen similar complaints/codes on LS pickup trucks. Bad 02 sensors causing the lean codes and the misfire. A lot of time it will just throw a MAF code when it starts running bad. Easy way to verify is when it is running bad, leave it running and hook up a scan tool. Command car into open loop. This will ignore 02 readings and if they are the problem it will start running normal.
 

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Discussion Starter · #17 ·
It seems like alot of people are saying it could be a ground. Ill look further into that once it stops raining so much. I will say I am making a tirp to the dealer to see what I can get on a trade in. I just remembered that when I did the whole shutdown/lose power/sputter the first time, the CEL light came on after it did that but the stability either cut off or said I lost traction (I know I didnt). I dont fully remember just because I was in the left lane of a 5 lane highway and couldnt accelerate.
 

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Let my friend who owns tunetime read the thread says Cats may be bad? Not allowing engine to breathe? That would set off lean codes, many same symptoms..
 

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Discussion Starter · #19 ·
I had a buddy that said the cats in his Impala were loose on the inside and caused the same symptoms. Its logical since after a long drive they heat up and might start bouncing around and block something since the DoD is slightly vibratory. What pissed me off is I told the dealership that it could be the cats or the ECU and to check them. Im unsure if they did that or just drove it.
 

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Usually if cats are bad, they are bad. There is no waiting on them to act up or anything like that.
 
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