In Oxygen Sensors
Your 1989 Lincoln mark vii lsc rpms are surging when it idles doen n e one know what the problem could be you have replaced the oxygen sensors in the exhaust is there any other sensors that could be?
I had a similar problem with my '89 Mark 7 Bill Blass and after much repair in the in-take manifold area it turned out to be the EGR Valve. I can't remember exactly what EGR s…tands for, but it has something to do with recirculating the car's exhaust. Answer If it get worse when turning the wheel you should try replacing the IAC (idle air control) solenoid. It should be located somewhere near the butterfly valve on the air intake. Answer It could be a trannsmission problem i have a 1989 lsc and my engine started racing because the car would'nt shift. It turned out to be a transmission problem. Answer Do a tuneup by replacing spark plug wires, use platinum spark plugs(verify the gap)-my 87 mark LSC used to eat regular autolite plugs and the spark gap would end up being wrong. Replace the Cap and rotor. also, replace the Idle speed controller-(get from local autoparts store)-do not forget to disconnect the battery. Clean the Throttle body valve and IAC with Throttle body cleaner using 2 rags-do not let the fluid get down into the manifold. Also, replace the fuel filter and use fuel injector cleanner. Start it up and be surprised at how well it runs. You may want to replace the IAC but I suggest cleaning it first. ( Full Answer )