HELP!!!...Car falls on it's face and bangs once after powerbraking!

[coolguywalt]

I went out on a test drive with my potential buyer for my GN and at about 8psi, the car looses all boost and falls on it's face. But then it drives regularly with no real boost. If I try to get on it, it just kind of dies for a moment, makes a small bang (like a IC pipe hitting something), building no boost, then picks back up again once I take the foot of the acellerator. The car ran perfect before that. Checked all the hose clamps, all the vacuum lines, all seem to be in good working order. The car has the Spearco FMIC on it, and the hoses look fine and it idles fine: no excessive temperature, FP around 60, oil pressure around 35psi, I am stumped. I did a search on the board and didn't find much.

Someone PLEASE help!

I think it might be an ignition problem...... anything that I can test to see if it might be a bad coil pack?

 

[Warp6]

check all your grounds. Especially the ones behind passenger head

 

[GNX423]

Sounds like what happened to me when the crank sensor was going, if it continually gets worse, i would change the sensor, i think it was only $35-40. alot cheaper than the ignition module that i changed first ! ($180)
Good luck,
Mike

 

[2QUIK6]

Fuel pressure at 60#'s?? That's a bit excessive unless you are at 15# of boost, could be way too rich....
Coil pack and grounds would be the next thing to investigate.
You can measure the resistance across each of the 3 coils, should be in the 11k-13k ohms range, but even this could show ok and the coil or ignition module be bad. Mine ohmed fine but mine would pop at about 10# of boost. Bought a Coil/Ign module tester from Caspers and 2 coils would loose spark at about 6k rpms under no boost.....add boost conditions and I'm sure the spark would blow out alot sooner.....changed the coil and problem was solved.

 

[UNGN]

Does the car have a new fuel pump in it? That is a ton of fuel pressure.

If the pump isn't new, it could be bypassing when you start to power brake it.

 

[milesengineer2]

I would definitely give the IC hoses a second look. Loose clamp, may have blown one off, anything could happen.

 

[Blown&Injected]

MAF?
TPS?
O2's?