Questions and Answers
Intermittent Starting Problem
Q. The auto in question is a 2001 VW Passat GLX with the 2.8L V-6, 190HP, Tiptronic, front wheel drive. The owner's manual specifies 91 octane premium which is generally not readily available. Regular is usually 87 octane, mid-premium is 89 and premium is 93.
Alternating fillups between full and mid premium would be close enough, but like most modern engines it is equipped with knock sensor(s) to prevent harmful detonation.
The engine is quite powerful and smooth running and I'm hard pressed to feel the difference between the power output using the specified octane and just using regular. I realize the engine computer will compensate for a lower octane and produce less power, but are there any lasting harmful effects from using regular on a continuing basis?
I only use name brand gasolines that have full detergent and additive packages in their regular grades as they have in the premium lines and purchase from service stations that sell a large volume of gas so their deliveries are regular and the gas is "fresh". If it's of any consequence, 75% of my driving is at highway speed, I average 15,000 miles a year and rarely keep my vehicles beyond 3-4 years.
A. Assuming this is an ignition problem due to the fact that there is no spark, a couple of possibilities come to mind.
With new cap, rotor and wires we can eliminate the secondary side on look at the primary side. The first thing to do is check the connectors for the ignition coil, igniter and distributor. If the connections are clean and tight there is a problem with one of the components I have mentioned.
The problem with testing these components is that they have to be tested when the symptoms are manifesting themselves. Otherwise everything will check out fine and you'll be back where you started. Intermittent problems like this can be very difficult to track down. Sometimes it needs to become a steady problem to locate the cause.
If you put a gun to my head and made me take an educated guess, I would say the igniter is probably the most likely problem.
Additional Information provided courtesy of ALLDATA
