Running problem?

supersix17 · #1 (**permalink**) 10-29-2008, 11:58 PM

I race a 97 bonneville on a half mile asphalt oval. My problem comes in when i am coming out of the corners. I run constantly with the car in 2nd gear and will hit about 5000RPM down the stretch. When i go to get back on the gas coming out of the corner the car seems to dog down and not really have power again until i get mid way down the straight. Does anyone have any ideas for me. I know this is a big part of how i am getting beat so any suggestions would be greatly appreciated.

My other question is would this be caused by the tranny going into 3rd and locking in even though i physically shift to second before i start? I know it will downshift to first when i slow way down but just wasnt sure if, when it is getting wound up if it will shift to third automatically like it does from first.

n0dih · #2 (**permalink**) 10-30-2008, 01:01 AM

You could do a PCM tune on it (I can at least) and set it up for manual shift or to do exactly as you want.

But as for losing power coming out of the turns, it sounds like likely fuel related. Those cars didn't have that great of a fuel tank pickup like the 00-up Bonnevilles. So try to find a way to monitor fuel pressure when you are on the track. Even a AC pressure sensor could be made to monitor fuel pressure (not sure how long is safe) and you can datalog through the AC high side pressure sense port to the PCM.

supersix17 · #3 (**permalink**) 10-30-2008, 01:04 AM

Alright thanks. That was one of the places i was going to look at was fuel pressure from the pump and the injector spray pattern. I was also wondering.... Would a bad MAF sensor or MAP sensor do it. I think the MAF sensor is like 180,xxx and so is the MAP prolly.

n0dih · #4 (**permalink**) 10-30-2008, 01:13 AM

i would not expect the MAP or MAF to be problematic if that is the only place you are doing it, they would be a problem probably most of the time. If you are uncovering the pickup (easy to do) that would do it. Also be very careful you aren't uncovering the oil pump pickup. Front wheelers aren't ever intended to do hard corning (9C1 Impala maybe) so the oil pans weren't designed for cornering. You might also want to do some oil pan mods to ensure oil around the pump at all times (study a fuel pump bucket for thoughts on it...Baffles and trap doors are good things....

make sure you have at LEAST 1/2 tank of fuel.... I would probably go with 3/4 to be safe.

supersix17 · #5 (**permalink**) 10-30-2008, 02:40 PM

well it feels doggish all of the time not just coming out of the corners. That is just where I notice it more because people can pull me pretty well off of the corners. Im thinking about putting a fuel cell in it for next season and hopefully eliminate a problem with fuel but right now cash is tight and i am trying to find a sponsor that wants there name on the car to help out. I haven't had a chance to hook it up to a pressure test yet though. What would a bad MAP sensor cause as far as symptoms? Is it possible, because it is doing it all the time that it could be these sensors?

imp0ster · #6 (**permalink**) 11-03-2008, 08:34 PM

Your car doesn't have a Limited Slip diff. Depending on which way you're cornering the diff will actually load power to the wheel that doesn't deserve it. My other guess would be you're slipping it. Kinda like a 1 wheeled burnout

n0dih · #7 (**permalink**) 11-03-2008, 11:55 PM

Yup, you wanna corner fast, gotta have a LSD.... Inside tire has a shorter radius, why put power into the one with the longer radius?

Yup, that is what I thought.....