My buddy just finished building his 03 Cobra.. Here's what he has installed..
5 liter built bottom end
stock heads
stock cams
Whipple kit with air/water cooler
2.8 upper/stock lower
60lb injectors
SCT2400 MAF
Modified stock pumps (not sure of the kit.. but it basically uses a larger diameter fuel hose and bridges the stock pumps with a larger Y fitting)
SCT tune copied from a running vehicle with the same injector/maf combo, just to get the car started to break in and dyno.
The car starts.. runs fine for about 5 minutes.. and then progressively gets worse as time goes on.. after 6-7 minutes.. the car is sputtering/backfiring, and won't stay running. Let the car sit for a day or so.. start it back up.. same thing.. runs fine for a few minutes.. then, starts running like crap.
All parts are brand new.. I've checked all of the obvious stuff.. ground wires, leaks, checked to make sure the MAF was getting 12 volts switched power. I'm not sure what else there is to check.. I'm thinking he's got a bad ECU, or MAF. The car would act up before he rebuilt it.. sometimes it would just start misfiring for a second or two..
Also, he is on his second lower pulley in about 10 minutes of run time.. He keeps sheering the pulley loose from the main shaft that screws into the harmonic balancer.
Odd stuff.. I'm not sure what else to try, except for a new ECU.. any suggestions?
5 liter built bottom end
stock heads
stock cams
Whipple kit with air/water cooler
2.8 upper/stock lower
60lb injectors
SCT2400 MAF
Modified stock pumps (not sure of the kit.. but it basically uses a larger diameter fuel hose and bridges the stock pumps with a larger Y fitting)
SCT tune copied from a running vehicle with the same injector/maf combo, just to get the car started to break in and dyno.
The car starts.. runs fine for about 5 minutes.. and then progressively gets worse as time goes on.. after 6-7 minutes.. the car is sputtering/backfiring, and won't stay running. Let the car sit for a day or so.. start it back up.. same thing.. runs fine for a few minutes.. then, starts running like crap.
All parts are brand new.. I've checked all of the obvious stuff.. ground wires, leaks, checked to make sure the MAF was getting 12 volts switched power. I'm not sure what else there is to check.. I'm thinking he's got a bad ECU, or MAF. The car would act up before he rebuilt it.. sometimes it would just start misfiring for a second or two..
Also, he is on his second lower pulley in about 10 minutes of run time.. He keeps sheering the pulley loose from the main shaft that screws into the harmonic balancer.
Odd stuff.. I'm not sure what else to try, except for a new ECU.. any suggestions?