Luke writes:
Sajeev, I was hoping you’d have an answer to my unusual problem and post my letter so I may get some feedback from the brilliant people who visit your website. I bought a 2004 GTO (automatic) back in September ’09. It’s in beautiful condition, yet has an unusual plight. Here goes:
If I fill the gas tank 3/4-full, the engine chokes and surges and will often times stall. Engine speed drops and then it revs and drops and revs again… and sometimes drops so far it just quits. I get the impression it’s drowning in gasoline and gasping for air. I don’t always fill my gas tank and was able to diagnose the syndrome myself after the 3rd irregular occurrence. It’s downright dangerous in heavy traffic, slogging around town, as I nearly lunged out into cross traffic the last time it happened. I was able to jump on the freeway and keep the engine revving. By the time I made it to my friends house I had burned off the first quarter tank and the car was back to normal. For the past 4 months I’ve been careful to keep the tank below 3/4 full and the car runs great. Having moved to Knoxville, TN, only about a year ago, I don’t have a network of trustworthy acquaintances. I’d rather not take it to a shop that’ll cash in on me. One wanted to rip my engine apart for $1000 dollars. It’s only got 40K miles on it. I’d love to go in knowing what I need.
I’ve done as you asked and took my car to Advanced Auto to check for stored codes. There were none found. It would have been important for me to note that my engine light did come on one time and one time only. In the midst of the first occurrence, I accelerated hard and the engine light began to flash. I slowed and the light shut off after a few seconds. The light did not come on during the second two episodes under normal driving conditions. My owners manual states: “If the (engine) light is flashing, a misfire condition has been detected.”
Sajeev answers:
Consulting with car enthusiasts that have no financial ties to your vehicle’s repair needs is pure brilliance. That said, I better start armchair quarterbacking: I can’t believe the GTO didn’t throw a code, save it in the computer and eagerly share it with your scanner. But here we are!
Given the problem(s) presented, the Goat must have a problem with the evaporative emissions system. A quick check of LS1GTO.com found an extremely relevant thread. After clicking on that link, there’s nothing more I can add!
Bonus! A Piston Slap Nugget of Wisdom:
Just kidding, there’s more to discuss: everyone who cares about their car and/or wallet should be a (somewhat) active member of their ride’s on-line forum. As someone who’s been in the forum moderation business for a decade, I know there’s no better source for model specific problems. So just do it.
(Send your queries to mehta@ttac.com)
With a misfire condition severe enough to flash the light, you should have set a random misfire code (p0340?). Like Sajeev, I am confused that your code reader didn’t at least show that. If I remember correctly, OBD-II is required to store emission related codes until cleared manually. There are some codes that will clear after a few ignition warm-up/cool-down cycles, but emissions related should not.
Car forums are a great way to find out what is going on with your vehicle…..chances are that you are not the first to have something specific happen. I even found one thread for my Miata that showed pics and step-by-step complete teardown and rebuild of the Torsen limited-slip after my X (then not X) put the donut spare on the rear after a blowout
Fuel Filter or Fuel Pump
My guess is the EVAP system is injesting raw fuel, instead of vapors. This would occur with a misplaced EVAP inlet fitting in the fuel tank that drinks the fuel when the tank is very full, or under heavy acceleration.
The misfire code could occur under these conditions.
+1
Not 100% sure about holden/GM systems, but there is probably a canister at the top of the fuel filler neck. My guess is the previous owner topped off often enough to overflow the filler neck and saturate the evaporative canister there. That’s likely not going to be cheap to replace, the salvage yard is going to be your friend.
might be a bad purge valve, or flooded charcoal evap container.
And don’t go back to that shop! Might be a good time to pick up all the manuals for the GTO, especially if you plan on keeping it a long time. If you’re gear head enough to own a GTO then it’s time to get some wrenching skills. (If you don’t have them already.)
Know where I can find a repair manual?? The Haynes GTO repair manual is not easy to come by…
Found a few on eBay by searching 2004 GTO in the “manuals and literature” section of eBay motors.
Some on this site too: http://www.themotorbookstore.com/pogtocovtvxv.html
I agree with ctowne and the others that mentioned flooded evap canister. After the first click of the pump at the gas station, pay the bill. Do not let some inexperienced pump jockey keep clicking until they can get every last drop in there.
Luke, on the bright side you’re able to get a full tank of gas. I’ve never been able to get my GTO to take much over 3/4’s tank. The pump keeps clicking off after that, even if I pump it slowly.
Oh…and the the damn rear tires keep wearing out.
I had a problem like this on one of my old cars, almost causing me to get into a couple of wrecks before it got fixed. It would rev/surge, sputter, stall etc, and it took me a while to figure out it was the Evap system, and filling the tank all the way up made it happen, or made it a lot worse. Gas could be smelled in a closed garage when the tank was full, but it wasn’t all that strong, at first. I started checking around under the hood when it got really strong, and the evap canister was full of gas and was very heavy. I took it to the dealer, and they knew what it was, and I don’t remember how much it was, but it wasn’t bad at all, like maybe $100 total. I think it was a check valve someplace had stuck open, and it let raw gas be sucked into the canister.
Thanks, everyone, for your input. And thank you, Sajeev, for posting my letter. I have enough information now and know where to begin with this.
I am a member of LS1.com and did my best to search it and LS1GTO.com for subject matter similar to my problem, but I had a difficult time finding anything. That is when I decided to write in to TTAC. This venue provided me with the terminology I was looking for in order to search for the information I needed!
Thanks, again!