I am helping a girlfriend with her '87 Grand National and can not keep it running. The engine starts and runs fine for one-two minutes and then sputters and dies. Immediately after start-up without touching the throttle, the engine will change idle speed slightly as it goes through its initial warmup. Then it will idle smooth and constant for about one minute, then will start to miss, sputter and die. Pumping the throttle at this point just prolongs the missing before it dies. Once warmed up, the engine will die sooner after startup. Starting is good and predictable. What could be the problem?
CAR HISTORY AND DIAGNOSTICS PERFORMED: The engine required an overhaul which was performed by the professionals at Grooms. With installation of the engine a new heated O2 sensor was installed. The timing and throttle position sensor were set with the help of a very experience GN buff. I have already installed new PCV valve, new knock sensor, vacuum lines. Fuel pressure was checked and is within spec even as engine dies. Vacuum is neg 15-20 inHG depending on idle speed reached. Vacuum holds well after engine dies. Compression check with cold engine is 130-150 psi on all cylinders. CAN ANYONE HELP? My email address is oneillwn@yahoo.com Thank you.
CAR HISTORY AND DIAGNOSTICS PERFORMED: The engine required an overhaul which was performed by the professionals at Grooms. With installation of the engine a new heated O2 sensor was installed. The timing and throttle position sensor were set with the help of a very experience GN buff. I have already installed new PCV valve, new knock sensor, vacuum lines. Fuel pressure was checked and is within spec even as engine dies. Vacuum is neg 15-20 inHG depending on idle speed reached. Vacuum holds well after engine dies. Compression check with cold engine is 130-150 psi on all cylinders. CAN ANYONE HELP? My email address is oneillwn@yahoo.com Thank you.
