huge launching problem

[1fast97gsx]

Some background info on my car that may be helpful is that this is a totally different motor than the one I first had this problem with last summer, and a lot of other things were replaced and upgraded over the winter as well. These things include the ecu, coilpacks, power transistor unit, engine ( 6 bolt swap ) transmission, new flywheel, new injectors, new slave cylinder, new clutch line and a few other things as well. The system was tested for boost leaks and none were found up to 25 psi. Fuel cut is also supposedly removed with my dsmchips chip that is installed on my eprom ecu.

When I first started having this problem was about a year ago on my old 7 bolt. I would go to the line and rev the engine to about 5000 rpm and hold it. On green I would slip the clutch and take off no problem. ( I ran consistant 1.7 60 foots for a year straight the year before and up until this point so it's not my launching technique )

When this problem first started I lined up and got ready to launch like normal. I held 5000 rpm and started slipping the clutch. Just as I was all the way out with the clutch the car would lose all power and nose dive even though I was still 100% on the throttle. Once it did that it made a huge pop out the exhaust and then started to make power again instantly. Last summer I didn't do any racing and since this only affected my launching I never worried about it again. Now I did a 6 bolt swap and replaced all the other things listed in the top of this post and went to launch it again and it still has the problem. Could it be a simple clutch adjustment causing it to do this without me actually noticing it slip by looking at the tach? Today when I launched the car it spun the tires really hard and kicked out to the right. Once I was at about 6500 rpm or so it once again nose dived and made a huge pop and then took off again. ( I shift around 7500 - 7800 ) I can't figure out what would make it do this since everything seems fine when I'm not launching it ( even if I roll off the line and then floor it I don't have any problem ) and when I do 3rd and 4th gear pulls my logs check out perfect and there is no clutch slipping. Spark plug gap is set correctly and I tried 2 sets of plugs so I'd rule that out. I just don't understand whats going on here!!! Sorry for the long post, I just didn't want to leave any information out. Thanks for your help in advance.

 

[AMS stampy]

Eric #2 over here is thinking it might be the positive terminal of the battery hitting the strut tower bar. Or something relating to a possible short connection that is being severed on a hard launch.

Eric

 

[1fast97gsx]

well that was something I first considered when the problem started, however now the battery is relocated to the trunk with nothing near it that it could hit or ground out on. Any other ideas?

 

[1fast97gsx]

Could a bad front O2 sensor cause something like this?

 

[Jeff91AWD]

Wow, my car is doing the SAME thing , I am trying to track it down right now too. I thought a ground connection, could be severed like was said before also, but i am fairly sure they are good.


I'll keep looking

 

[jameswemm]

im having the same problem .im new and thought it was fuel cut.so i did all the mods and it still does it .please post if you figure out what it is.

 

[1fast97gsx]

It turned out being my fuel pump ... I got a better one and all is well.

 

[Jeff91AWD]

Cool, Thanks for the update , The previous owners of my car did anything and everything wrong, and i have yet to get to the fuel pump area, but i know its got problems, because i saw sheet metal screws holding down the fuel pump access plate. They are screwed DIRECTLY into the gas tank. GRRRRRRRRR...