TO: ALL YOU AUTO MECHANIC ""BRAINIACS, HELP!!
I HAVE A 1984 CADILLAC WITH A GAS HT4100 ENGINE. CAR HAS 161,000 MILES DRIVEN BY ME SINCE I BOUGHT IT NEW. CAR HAS BEEN ALWAYS WELL MAINTAINED ON A PREVENTATIVE BASIS, SIMILAR TO THE WAY AIRCRAFT ARE MAINTAINED. IT COMES NATURALLY SINCE I AM A RETIRED B-747 JUMBO JET CAPTAIN WITH 33 YEARS CAPTAIN WORLDWIDE EXPERIENCE PLUS CAPTAIN RATED AND EXPERIENCED IN 17 DIFFERENT JET MODELS FROM THE LEAR JET TO THE B-747.
I ALSO HAVE A 1990 LINCOLN TOWN CAR I BOUGHT USED IN 1999 WITH 80,000 MILES ON IT WITH A CLEAN AND CLEAR RECORD VIA CARFAX. LINCOLN NOW HAS 99,000 MILES ON IT. AGAIN I AM THE ONLY DRIVER SINCE 1999.
THESE TWO CARS ARE MY 2ND AND 3RD CARS AND NOT DRIVEN REGULARLY, BUT AT LEAST EACH IS DRIVEN ONCE EVERY TEN DAYS OR SO FOR AT LEAST 20-25 MILES ON THE FREEWAYS IN THE PHOENIX, AZ AREA.
BOTH CARS RUN EXCEPTIONALLY WELL AND ALL SYSTEMS AND ACCESSORIES ARE OPERATIONAL AND WORK FINE.
NOW FOR THE PROBLEM. BOTH CARS HAVE EXACTLY THE SAME SYMPTOMS. WHEN THE CARS AND ENGINES ARE COLD AND EARLY IN THEIR TRIP UP TO ABOUT 20 MILES THE THROTTLE RESPONDS VERY NORMALLY ON ACCELERATIONS AND DECELERATIONS. HOWEVER, AFTER ENGINES GET GOOD AND HOT (NOT OVERHEATED), ON NORMAL DECELERATIONS WITHOUT THE BRAKES APPLIED, LIKE SLOWING FROM 55-60 MPH FOR AN APPROACHING RED LIGHT OR A HARD TURN, THE ENGINES DO NOT DECELERATE TO IDLE AND WILL MAINTAIN A SPEED OF 40-45 MPH WITH YOUR FOOT OFF OF THE ACCELERATOR PEDAL. WHEN THIS HAPPENS I SHIFT INTO NEUTRAL SO AS TO NOT ABUSE THE BRAKES. SHORTLY AFTER STOPPING AT THE STOP LIGHT AND WITHOUT TOUCHING THE ACCELERATOR PEDAL THE ENGINE WILL FAIRLY RAPIDLY AND ON ITS OWN, REDUCE THE POWER TO THE NORMAL IDLE SPEED. ONCE THE CARS ARE “HOT” THIS SITUATION OCCURS ON EVERY STOP YOU MAKE WITH THE A/C ON OR OFF, UNTIL YOU PARK THE CAR LONG ENOUGH FOR THE ENGINE TO COOL TO AMBIENT TEMPERATURES. ON RAPID STOPS AS INTO A PARKING LOT WITH A QUICK SHIFT INTO PARK, THE ENGINES WILL “FAST IDLE” FOR ABOUT 1&1/2 MINUTES BEFORE IT WILL DECELERATE TO NORMAL IDLE SPEED.
I ALWAYS USE CHEVRON “REGULAR,” CHANGE OIL AND FILTER EVERY 6 MONTHS OR 3000 MILES WHICHEVER IS FIRST. BOTH OF THESE CARS HAVE CARBURETOR CARS WITH SOME BASIC EARLY COMPUTER SYSTEMS. IT SEEMS TO ME THAT SINCE BOTH CARS ARE UNAFFECTED BY HAVING THE A/C ON OR OFF AS THE SYMPTOMS REMAIN THE SAME EITHER WAY. ANY SUGGESTIONS AS TO WHAT IS WRONG?
THANKS,
CAPTAIN JAMES SANDERS, RETIRED
SCOTTSDALE, AZ
602-717-4602; Call After 2:00 PM Mountain Standard Time, PLEASE. Leave number if get voice mail as I am in a wheelchair and
I can’t always get to the phone before it goes to voice mail. Thanks
www.captjasanders@gmail.com
A Lincoln and a Cadillac are 2 different animals, in both manufacture and design, so I think you need to address each problem separately. Having said that you need to look at cables for throttle, are they both carburetor fuel delivery? then perhaps a good carb clean and make sure nothing is sticking can fix the problems, it is unlikely though the symptoms are the same that the repair will be the same.
I would say to get the respective manual out for each model car and get familar with what controls the idle speed for each car.