01-26-05, 05:23 PM
I have a 95 SLS. When I am driving it surges really bad when I let off of the gas pedal. Sometimes it will surge so bad that it kills the car. It is also running really rich. It smells like gas all of the time when I drive it. It is only setting one code, which is the 56 Input Speed Circuit problem, which I was told is a transmission censor? I don't know if a transmission censor could make all of my problems happen? It also has a problem starting if it sits for an hour or two, but if it sits overnight it starts fine. It also starts fine if it has just been killed, like when i run into a gas station. I have changed the plugs and wires on it. I have also cleaned the Injectors with seafoam. Nothing seems to help this car :banghead: !!!! I have already spent alot of money on this car, PLEASE HELP!!!!!
01-26-05, 11:39 PM
Sounds like a classic fuel pressure regulator that has ruptured and is leaking internally.
Find the fuel pressure regulator on the fuel rail. It is the small canister like device at the fuel return line with the vacuum line to it. With the engine idleing, remove the vacuum line and watch the vacuum nipple on the FPR for several minutes for any sign of gasoline seeping out. Chances are you will see gas. Bad FPR. Replace the FPR. Kit is available at dealer for the FPR.
02-02-05, 09:54 PM
Thanks for the help. I checked the FPR and it shot out gas when I removed the vacume hose. I had to order the FPR and it came in today. I put it on and it fixed most of my problems. The only one it didn't fix was my code for the 56 Input Speed Circuit problem. If you know what that is reply it back. Otherwise thanks for the great advise.
02-03-05, 12:35 AM
The input sensor seems to be a common failure. Look here for how to diagnose. http://www.cadillacforums.com/forums/showthread.php?t=30445
02-10-05, 02:32 PM
32V DOHC Thanks for your help. I had a mechanic tell me that this sensor is located on the inside of my transmission. He told me that it would be a big job to do. I need to know how to get to the sensor, and if I could do it myself.
The input speed sensor is a $20 part located $2000 deep in the trans. I believe you have to drop the trans and remove the side cover to get at it.