Need Help

boosted231

Member
Joined
Sep 13, 2003
A couple of weeks ago I took my GN in for the emissions test. Car ran fine on the way to the emissions station. It failed on HC with limit .8000 Grams/Mile and mine blew 4.6368 and also failed on NOx with limit 2.000 Grams/Mile and mine blew 4.5719, CO passed with limit 15.0000 Grams/Mile and mine ran 13.6351 Grams/Mile. When I left the emissions station and headed home on the highway about 60 mph the car started backfiring through the exhaust and bucking. I put on a new ign mod and coil pack and plug wires and now the car idles very smooth but under acceleration the backfire and bucking starts up again. I put a new O2 sensor in it with no improvement. I also checked the positive battery wire to see if it was touching anything and it looked fine. I have a stock motor with a walboro fuel pump hotwired, stock turbo, stock injectors, stock chip, THDP with cat and ATR exhaust. Fuel pressure is set at 42 line off. What in the world is going on?
 
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