1991 Geo Storm

AT AN IDLE, IN PARK OR IN GEAR, THE ENGINE SPEED OFTEN RISES FROM NORMAL (1000RPM) UP TO AS HIGH AS 4000 RPMS. THIS HAPPENS AT A STAND STILL AND ALSO WHEN APPROACHING, SITTING AT OR LEAVING STOPP LIGHTS ALSO. THIS PROBLEM HAS CAUSED UNWANTED AND UNSAFE "LURCHEING" FORWARD WHEN LETTING OUT THE CLUTCH. AT TIMES, WHEN THE ENGINE SPEED COMES BACK DOWN, IT WILL DROP TOO FAR AND CAUSE THE ENGINE TO STALL. THIS HAPPENED TO ME IN THE MIDDLE OF A BUSY INTER SECTION AND I WAS NEARLY REARENDED. TO MY KNOWLEDGE GM IS AWARE OF THIS PROBLEM BUT REFUSES TO TAKE CARE OF IT OUTSIDE NORMAL WARRANTY PERIOD.*AK

ERRATIC IDLE SPEED THAT REVS AND DROPS WHILE YOU ARE COASTING OR AFTER YOU COME TO A STOP. SOMETIMES IT REVS HIGH INTO THE RPM RANGE ABOVE IDLE SPEED, SOMETIMES IT DROPS SUCH THAT THE ENGINE NEARLY DIES OR DOES DIE. HOVERING IDLE SPEED THAT HANGS AT CRUISING LEVEL WHILE YOU ARE COASTING OR AFTER YOU HAVE COME TO A STOP, USUALLY 2,000-3,000 RPM. SOMETIMES, IF YOU WAIT A WHILE, IT COMES DOWN ON ITS OWN, SOMETIMES IT DOES NOT.HOVERING IDLE SPEED THAT HANGS AT CRUISING LEVEL WHILE YOU ARE COASTING OR AFTER YOU HAVE COME TO A STOP, USUALLY 2,000-3,000 RPM. SOMETIMES, IF YOU WAIT A WHILE, IT COMES DOWN ON ITS OWN, SOMETIMES IT DOES NOT. ISUZU AND GEO HAD IN THE PAST (ONLY WHILE THE CAR WAS UNDER WARRANTY) REPLACED THE ECU TO SOLVE THE PROBLEM. ISUZU AND GEO HAD IN THE PAST (ONLY WHILE THE CAR WAS UNDER WARRANTY) REPLACED THE ECU TO SOLVE THE PROBLEM. IT IS MOST DANGEROUS ON THE AUTOMATIC MODELS BECAUSE THE AUTOMATIC TRANSMISSION USES ENGINE SPEED AS A REFERENCE TO CONTROL THE ENGAGEMENT OF THE TORQUE CONVERTER (IF THE ENGINE SPEED IS ABOVE 900 RPM, THE CAR MOVES FORWARD) SO HOVERING IDLE SPEED IS OF GREATEST HAZARD TO AUTOMATICS. IT IS ALSO A HAZARD FOR MANUAL TRANSMISSION CARS BECAUSE ENGAGING THE ENGINE AT 2,000-3,000 RPM WILL RESULT IN VIOLENT FORWARD MOTION. IT IS MOST DANGEROUS ON THE AUTOMATIC MODELS BECAUSE THE AUTOMATIC TRANSMISSION USES ENGINE SPEED AS A REFERENCE TO CONTROL THE ENGAGEMENT OF THE TORQUE CONVERTER (IF THE ENGINE SPEED IS ABOVE 900 RPM, THE CAR MOVES FORWARD) SO HOVERING IDLE SPEED IS OF GREATEST HAZARD TO AUTOMATICS. IT IS ALSO A HAZARD FOR MANUAL TRANSMISSION CARS BECAUSE ENGAGING THE ENGINE AT 2,000-3,000 RPM WILL RESULT IN VIOLENT FORWARD MOTION.