Q: I have a ’96 Buick LeSabre. It runs well and has been well maintained. My car’s problem is that the engine occasionally will not start up. It always starts well the first time after sitting overnight. However, sometimes when I get back in it, it will crank but not start. If I wait an hour or so, it usually starts up. I have been warned that I might be flooding the engine, but I’m positive that I am not touching the gas pedal when attempting to start it. Sometimes it will go weeks without the problem and sometimes the difficulty in starting the engine will occur several times a week. I have had the car in to be checked for this but it didn’t occur in the few days the shop had it so the technicians were unable to locate the cause. Do you have any ideas? – L.C., e-mail

A: I believe your Buick has a crankshaft position sensor or ignition module going bad. Either one of these could become problematic when they get hot, causing intermittent operation. The circuits from the crankshaft position sensor plug into the ignition module and the circuits from the ignition module are connected to the powertrain control module (PCM). The PCM ultimately controls the spark at the spark plugs via the ignition coils and the fuel injected into the engine via the fuel injectors. If the PCM doesn’t see the proper pulsed signal from the ignition module (or crankshaft position sensor) it will not trigger the ignition coils and fuel injectors. To solve your car’s problem, you could have your mechanic replace both the crankshaft position sensor and the ignition module. However, I would suggest the technician diagnosing the problem carefully use a heat gun on each component (crankshaft position sensor and ignition module) to see which one is the cause of the no-start condition.

Q: My problem lies with the fading of my brake pedal after a stop in my 2008 Lincoln MKZ. The pedal will fade almost to the floor while sitting at a stoplight. If your foot is not squarely on the brake pedal you can engage the top of the gas pedal causing the car to accelerate or not stop. This has happened twice since I’ve had the car. My question: Why does the pedal fade? With hydraulics, this should not happen. In the days before antilock brake systems you had a firm pedal and now it seems to be a softer pedal. If your pedal faded you either had a leak or your master cylinder was bad. Lincoln has checked my car and says the pedal is normal. I say baloney. I lived in Florida for 17 years and about once a month you would read in the paper about someone plowing through a storefront or causing an accident because they thought they had their foot on their brake. I believe maybe their foot, while on the brake, sank low enough to contact the gas pedal. What do you think? – Bill, e-mail

A: I drive many different cars and the only ones I sometimes have trouble with are small sport cars that also have a clutch pedal. I have big, wide feet and they sometimes make it challenging to stay on the intended pedal. If your pedal is sinking, the braking system should be carefully inspected. You’re right, with hydraulically applied brakes the brake pedal should not sink once the wheel brake units are fully applied. However, if the hydraulic system has any trapped air (which is compressible), the pedal will sink. Maybe you should take your Lincoln to a repair shop that specializes in brake repairs to get another opinion.

Questions for Ira Siegel? Call the Auto Advisor Hotline at (708) 633-6839 or e-mail autoadvisr@aol. com. Siegel is an automotive instructor and an automotive service excellence-certified master auto technician.