roadie
03-14-2004, 08:36 PM
I have been having some serious consistency problems with my current car during drag racing and it has been causing me to loose a lot of rounds of eliminations and I really need some help in figuring this problem out.
For the past year I have been drag racing in the sportsman, sport compact and street classes with a 2003 Pontiac Grand AM SC/T. The car is bone stock, except for a K&N air filter, that’s it. The car is equipped with the 3.4l V6 engine and automatic transmission. For 2 or sometimes 3 runs in a row the car will be fairly consistent, usually within about 5 hundredths of a second in ¼ mile ET’s, and to me that in itself is quite acceptable for a car like this. And then all of the sudden without warning it will go 2 or 3 full tenths of a second faster or slower than what it had been running, and then on the next run again after that it will revert back to very closely what it had been running consistently before that happened, but then you never know when it’s going to happen again and if it will be faster or slower when it does as it goes both ways unpredictably. If it happens during time trials you dodged a bullet but you have no idea what to dial-in at because you don’t know “which car” is going to show up next time you come to the line with the inconsistency in the ET’s. If it happens during eliminations you will either be in danger of braking-out by quite a bit or not even being able to run anywhere near your dial-in time and all you can hope for is that your competition made a bigger mistake somehow, like red lighting, and that’s not likely to happen very often, I know.
I try to always keep the water temperature as exactly the same as possible at the start of each run, on the factory temperature gauge. I do exactly the same burnout procedure every time. I stage the car exactly the same way every time, as shallow as possible. I always leave off idle, from brake peddle to full gas, so that eliminates the launch rpm variable. Traction is not an issue as my 60 foot times are always almost identical, often identical to the hundredth of a second, or usually at least within 1 or 2 hundredths or each other, and I always use the same tire pressure. I normally leave the transmission in “3” all the time and let it shift itself, but this problem has happened on test days where I have shifted the transmission manually at the same rpm all day as well, so it’s not the transmission. It’s happened on cold days and on hot days, as well as cool and warm days, on days where the weather and temperature and barometer and adjusted altitude don’t change between runs, on sunny, on cloudy, on calm and on windy days, so it’s not the weather. I have tried days when I would try to cool the radiator and intake by spraying water on it between runs and days where I’ve never even lifted the hood between runs, and everything in between, with no differences. I have spent many days at the track testing trying to figure this out. I always leave the same amount of time between runs on test days, usually 45 minutes, to try an eliminate the amount of time between runs being a factor. I have tried using premium fuel and regular fuel with absolutely no differences.
I have been bracket racing for about 15 years, up until last year I raced a 1974 Oldsmobile Omega that was also basically bone stock with a 350 Oldsmobile V8 and a 4bbl carburetor, and obviously no factory computer or electronics, and the only thing that would affect it’s ET was the changes in the weather, and if there was ever a very drastic change in operating temperatures or track conditions, but at least then it was all very predictable.
I’m sure I’m not the only person to have tried to bracket race with a stock, computer controlled, electronic fuel injected vehicle, so some one out there must have encountered this type of thing before. So what’s going on here? What goes on inside these computer controlled engines to cause these inconsistencies? Are these things hypersensitive to very minor ambient changes or perhaps engine temperatures? Is there something that can be done to the car’s computer somehow to help? What can be done to prevent this problem from occurring? As specific as possible and proven tried methods to eliminate this problem would be much preferred, but any and all help will be much appreciated. Thank you.
For the past year I have been drag racing in the sportsman, sport compact and street classes with a 2003 Pontiac Grand AM SC/T. The car is bone stock, except for a K&N air filter, that’s it. The car is equipped with the 3.4l V6 engine and automatic transmission. For 2 or sometimes 3 runs in a row the car will be fairly consistent, usually within about 5 hundredths of a second in ¼ mile ET’s, and to me that in itself is quite acceptable for a car like this. And then all of the sudden without warning it will go 2 or 3 full tenths of a second faster or slower than what it had been running, and then on the next run again after that it will revert back to very closely what it had been running consistently before that happened, but then you never know when it’s going to happen again and if it will be faster or slower when it does as it goes both ways unpredictably. If it happens during time trials you dodged a bullet but you have no idea what to dial-in at because you don’t know “which car” is going to show up next time you come to the line with the inconsistency in the ET’s. If it happens during eliminations you will either be in danger of braking-out by quite a bit or not even being able to run anywhere near your dial-in time and all you can hope for is that your competition made a bigger mistake somehow, like red lighting, and that’s not likely to happen very often, I know.
I try to always keep the water temperature as exactly the same as possible at the start of each run, on the factory temperature gauge. I do exactly the same burnout procedure every time. I stage the car exactly the same way every time, as shallow as possible. I always leave off idle, from brake peddle to full gas, so that eliminates the launch rpm variable. Traction is not an issue as my 60 foot times are always almost identical, often identical to the hundredth of a second, or usually at least within 1 or 2 hundredths or each other, and I always use the same tire pressure. I normally leave the transmission in “3” all the time and let it shift itself, but this problem has happened on test days where I have shifted the transmission manually at the same rpm all day as well, so it’s not the transmission. It’s happened on cold days and on hot days, as well as cool and warm days, on days where the weather and temperature and barometer and adjusted altitude don’t change between runs, on sunny, on cloudy, on calm and on windy days, so it’s not the weather. I have tried days when I would try to cool the radiator and intake by spraying water on it between runs and days where I’ve never even lifted the hood between runs, and everything in between, with no differences. I have spent many days at the track testing trying to figure this out. I always leave the same amount of time between runs on test days, usually 45 minutes, to try an eliminate the amount of time between runs being a factor. I have tried using premium fuel and regular fuel with absolutely no differences.
I have been bracket racing for about 15 years, up until last year I raced a 1974 Oldsmobile Omega that was also basically bone stock with a 350 Oldsmobile V8 and a 4bbl carburetor, and obviously no factory computer or electronics, and the only thing that would affect it’s ET was the changes in the weather, and if there was ever a very drastic change in operating temperatures or track conditions, but at least then it was all very predictable.
I’m sure I’m not the only person to have tried to bracket race with a stock, computer controlled, electronic fuel injected vehicle, so some one out there must have encountered this type of thing before. So what’s going on here? What goes on inside these computer controlled engines to cause these inconsistencies? Are these things hypersensitive to very minor ambient changes or perhaps engine temperatures? Is there something that can be done to the car’s computer somehow to help? What can be done to prevent this problem from occurring? As specific as possible and proven tried methods to eliminate this problem would be much preferred, but any and all help will be much appreciated. Thank you.