Drove the car to work one day with no problems, it had been running fine up to that point. When I got off work 12 hours later car did not want to start, much longer cranking time than normal. Once it started it was idling very rough and then stalled. After 3rd or 4th attempt car started and seemed to be fine so I started down the road. Got less than a mile and car stalled out driving down the road. Had the car towed home, car does not want to start on it's own but will eventually. Car will start immediately with a brief shot of starting fluid in the throttle bottle. Once the car starts if you jockey the throttle from closed to any position the car seems fine as long as you rev-let off-rev-let off-rev-etc. If you try to let the car idle it dies within a few seconds, if you try to hold the throttle steady at any position it also dies almost immediately. As long as you jockey the throttle open/close/open it revs, slows and sounds fine. As soon as you try to idle or hold steady it dies. I thought I had a fuel delivery problem. This is a 1990 Chevy Corsica, 2.2L 4 cyl. With throttle body injection and distributorless ignition. The first thing I looked at was the air idle control valve, I removed it and started the car and it was moving in and out slightly so I assume it is fine, also the problem is not only at idle but at part open throttle as well (throughout the entire throttle range). I did however replace it with a junk yard unit. Next I replaced the fuel filter but no help. Next I installed a brand new injector in the throttle body, still no help. Dropped the fuel tank and replaced the fuel pump, no help. I then disassembled the throttle body regulator assembly and the diaphragm and spring appeared fine. I got a fuel pressure tester and have 12 PSI pretty steady at the throttle body inlet. I have removed and plugged each vacuum port from the intake manifold one at a time and found no difference. The only other possible vacuum leak would be the intake gasket which was replaced 5000 miles ago along with the head gasket and exhaust manifold gasket and new spark plugs. Or the throttle body gasket, but I have read that a vacuum leak would not be very noticeable with open throttle and I don't hear a leak. Plus the car accelerates fine, it's holding the throttle steady that causes the stall. I have checked the throttle position sensor output voltage it's.665VDC at closed throttle and increases smoothly through the open throttle range to around 4.5VDC which is slightly low at the high end but smooth throughout the range. I also checked the MAP sensor voltage with key on while sucking on the vacuum port and it starts around 5VDC and drops to about 1VDC and is smooth and drops as more suction is applied. The only OBD code displayed was a 23 which indicated a intake air temperature fault but at that time the breather was removed and the sensor unplugged. When I re-installed the breather and plugged the sensor in the code went away with no other codes present. I have tried running the car with the O2 sensor unplugged because I read that it would go into open loop mode without the sensor input and it made no difference, plus I don't think the O2 sensor would prevent the car from running would it? I did not do specific diagnostics on the crank position sensor as it is very hard to get to. I did buy a ignition tester (the type that goes in series between the plug & plug wire) and I see relatively slow sparking during cranking with a steady bright red continuous spark once it starts, the coil packs and wires were replaced about 4 years ago (50,000 miles?). The best I can tell is the fire is OK and I've read that if the firing looks good the crank sensor is working OK. My only other thought is to replace the ECM but it is fairly expensive especially if it does not help. I don't know what else to check, any help would be greatly appreciated.
have the same problem?
Saturday, May 18th, 2013 AT 6:38 PM